Andrew C. de Beaux
A hernia is defined as an abnormal protrusion of a cavity's contents, through a weakness in the wall of the cavity, taking with it all the linings of the cavity, although these may be markedly attenuated. The anterior abdominal wall can be divided into two structural/functional zones: the upper ‘parachute area’ aiding respiratory movement and a lower ‘belly support’ area. Functional failure in the abdomen may lead to epigastric and umbilical hernia in the upper zone and to inguinal and femoral hernia in the lower zone. The external abdominal hernia is the commonest form of hernia, the most frequent varieties being the inguinal (75%), umbilical (15%) and femoral (8.5%).
Hernias can be described as reducible, incarcerated or strangulated. A reducible hernia is one in which the contents of the hernial sac can be manually introduced back into the abdomen while, conversely, an irreducible or incarcerated hernia cannot be manipulated back into the abdomen. A strangulated hernia occurs when the vascular supply to the contents contained within the hernia is compromised, resulting in ischaemic and gangrenous tissue.
Multiple factors contribute to the development of hernias. Hernias are associated with a number of medical conditions, including connective tissue disorders such as Ehlers–Danlos syndrome, as well as a number of abnormal collagen-related disorders such as varicose veins and arterial aneurysm. In essence, hernias can be considered design faults, either anatomical or through inherited collagen disorders, although these two aetiological factors probably work together in the majority of patients. Anatomical design faults can be considered at any site where structures within the cavity exit through an opening in the wall of the cavity, such as blood vessels, bowel or the spermatic cord. This is typical, for example, around the oesophagus and in the groin. However, not everyone develops a groin hernia so other factors must be important. The fascia and surrounding tissues that cover muscle, acting to hold the muscle bundles together, may appear relatively avascular, but it remains a complex and living structure. The genetic code for fascia is coded on DNA, and within fibroblasts the sequence is messenger RNA, transfer RNA, peptide formation, with fusion of peptides into approximately 1000-amino-acid polypeptides called alpha chains. The endoplasmic reticulum converts these to procollagen. Procollagen is the large building block of collagen, comprising triple-helix strands, stabilised by hydroxylation of proline and lysine, which is vitamin C dependent. These triple-helix strands form microfibrils, then fibrils, then fibres and finally bundles. These collagen bundles surrounded by extracellular matrix comprise fascia. The control of this process is mediated through matrix metalloproteinases, which in turn are controlled by tissue inhibitory metalloproteinases. If this is not complex enough, there is also control by collagen-interacting proteins and receptors such as fibronectin, tenasin and collagen receptor discoidin domain receptor 2. Fascia and tendon are made up of type I and type III collagen (type II is found in cartilage and type IV in the basement membrane of cells). In cross-section, there is a bimodal distribution of bundle size. The larger bundles are type I collagen, imparting the strength to the fascia or tendon. The type III collagen bundles are smaller and are thought to provide elastic recoil following stretch when the tissues have been loaded. The type I to III collagen ratio varies between individuals but is constant in all the fascia of a particular individual.
A clinical observation was made by surgeons in the late 1960s that the anterior rectus sheath some distance from the hernial defect was thinner than normal, especially in those patients with direct hernias.1 Since then, research has demonstrated a variety of defects in collagen synthesis in such patients.2,3 The current notion is that the majority of hernias are a disease of collagen metabolism. One of the key factors in this is the type I to III collagen ratio. The lower this ratio, from an average of around 5, the more likely the individual is to develop a hernia. Currently, collagen typing is not used in clinical practice to help decide perhaps which patients merit a mesh as opposed to a suture repair, but this may well be a development in the near future.
Hernias are a collagen disease, with reduced collagen type I to III ratio.2,3
Much will be mentioned about mesh repairs of hernias in the remainder of this chapter, but this section gives a brief overview of mesh and its science.
Many companies produce a variety of mesh for hernia repair. These are either synthetic (man made) or biological (preparations from animal or human tissue). The majority of synthetic meshes are woven from either polypropylene or polyester. Biological meshes are typically animal collagen, either from skin or bowel, but there are also human preparations. Biological meshes tend to be much more expensive and are thus reserved for specialist use.
It goes without saying that any mesh should have the usual properties of any implant, including being non-allergenic, non-carcinogenic, have good incorporation into tissue and mimic the tissue it is replacing or reinforcing. The abdominal wall is not a rigid structure, but regularly copes with increases in abdominal pressure on coughing and sneezing, etc. of up to 200 mmHg. The abdominal wall elasticity is greater in women than in men and is greater in the craniocaudal direction than transversely or obliquely. The traditional standard weight polypropylene mesh, of around 100 g/m2, is significantly over-engineered, with a burst strength at least an order of magnitude greater than the anterior abdominal wall and an elasticity of much less.4 As a result there are now many polypropylene meshes on the market of lighter weight. There are no strict definitions of light weight and heavy weight but a reasonable guideline is that mesh of 40–80 g/m2 is medium weight and < 40 g/m2 is light weight. However, it is not just the weight of the mesh that imparts elasticity and flexibility. The weave of the strands in the mesh may impart varying flexibility or elasticity to the mesh in different directions of pull, so-called anisotropy. Pore size or the size of the large holes in the mesh is also important. Mesh has a volume with length, breadth and thickness. The amount of empty space within the ‘volume’ of the mesh is the porosity and the effective porosity is the amount of empty space within the volume of the mesh made up of holes that are bigger than 1 mm diameter. It has recently been proposed that an effective porosity of a mesh for hernia repair should be at least 60%.5 Fibrosis will occur around each strand of the mesh. If the strands are close together, the fibrosis around each strand will coalesce together, forming a solid scar plate. As the scar plate matures it will shrink, reducing the overall size of the mesh. The minimum pore size should be about 1 mm2 but many meshes have pore sizes around 3–5 mm. Increasing the macroporosity of the mesh produces a scar net, rather than a scar plate, with normal tissue in between the fibre/scar complex, reducing mesh/scar shrinkage and improving flexibility (Fig. 4.1). In addition to the macropore size, mesh also has micropores within the mesh material itself. These should be at least 10 μm in size. If the micropore size is smaller, bacteria can harbour in the pores out of reach of the larger inflammatory cells.
FIGURE 4.1 (a) Micrograph of a macropore mesh of < 0.5 mm pore size showing scar plate formation and contraction/distortion of the mesh. (b) Micrograph of a macropore mesh of 0.8 mm pore size showing minimal scar bridging and no distortion of the mesh. (c) Micrograph of a macropore mesh of 3 mm pore size showing scar net formation and no contraction/distortion of the mesh. Micrographs used by permission of Covidien UK.
The majority of synthetic meshes in the UK are polypropylene. Gore-tex and other polytetrafluoroethylene (PTFE)-based meshes also have some popularity. PTFE has no macropores so will be encapsulated by fibrous tissue with minimal tissue ingrowth. Polyester-based meshes are gaining popularity and have some advantages over polyproplyene but are multifilament rather than monofilament. The multifilament arrangement increases the developed surface of the mesh (around 2000 mm2 per cm2 mesh as compared to 200 mm2 per cm2 for polypropylene) and thus improves tissue incorporation. As a result, the peel strength (the effort required to separate the mesh from the tissues once it is incorporated) is greater, in the region of 190 N as compared to 160 N for a polypropylene mesh (Fig. 4.2).
FIGURE 4.2 Micrograph of a polyester mesh fibre. There is evidence of fibrosis around the fibre bundle as well as fibrous ingrowth around each strand. Micrograph used by permission of Covidien UK.
There is increasing evidence that lightweight, large pore mesh is of benefit to the patient.6 Although there are some reports that suggest the recurrence rate may be higher7 when such mesh is used, it is likely that this is due to technical reasons. Fixation sutures on such mesh should be placed at least 1 cm in from the edge of the mesh and slightly larger meshes may need to be used.
Preferred mesh should be lightweight (< 80 g/m2), large pore (> 1 mm) and macroporous (> 10 μm).6
Traditional meshes placed within the abdominal cavity have a high rate of adhesions of the omentum and bowel to the mesh. This can result in bowel fistulation or make subsequent laparotomy more difficult, with increased risk of bowel perforation and thus the need for bowel resection during the process of re-entering the abdominal cavity.8 A number of tissue-separating meshes are available, where the intra-abdominal side of the mesh is coated with a product to minimise adhesion formation. It would be fair to say that while such coatings do reduce adhesion formation, in the majority of patients significant adhesion to such coatings still occurs. The main points of adhesion appear to be the edge of the mesh and to the points of fixation, either sutures, tacks or staples. Nevertheless, it is likely that these products will improve in the future, as meshes become more physiological, perhaps impregnated with growth hormones and other biologically active molecules to improve the mesh/tissue integration.
Biological mesh (a slight misnomer as most biological meshes are really sheets of collagen) has gained popularity in hernia repair. It is, however, disappointing that, from the thousands of biological meshes that have been implanted worldwide (often at great expense as biological mesh is 10–100 times more expensive than polypropylene mesh), follow-up data on only just a few hundred patients have been published. What is becoming evident, though, is that biological meshes are not all the same. The major difference, in addition to the animal and anatomical source of the mesh, is the degree of chemical processing, or crosslinking, of the biological product. The more the collagen is crosslinked, the more resistant it is to bacterial collagenase breakdown in the presence of infection. The downside to crosslinking is that the more the collagen is crosslinked, the less tissue ingrowth and integration occurs, with reduction in potential strength to the repair. It is becoming evident that most biological meshes have no role in dirty wounds, acting as little more than a very expensive dressing. They are too expensive for use in clean wounds as any benefit is not worth the huge price difference, and using them for bridging (mesh spanning the fascial gap as opposed to augmentation, where the mesh reinforces or augments the fascial closure) also results in a high percentage of failure. The author's opinion is that there is no good evidence available to suggest that biological mesh is superior or even as good as polypropylene in clean/contaminated operations. Similarly, there is a lack of comparative evidence in contaminated operations, although fortunately this is a very small part of hernia surgery.
An epigastric hernia is defined as a fascial defect in the linea alba between the xiphoid process and the umbilicus. The true incidence is unknown but autopsy studies have suggested a prevalence of 0.5–10% in the general population. There is a male preponderance, with a male to female ratio of approximately 4:1, with the diagnosis usually being made in the third to fifth decades.
The aetiology is related to the functional anatomy of the ‘parachute area’. The anterior abdominal wall aponeurosis consists of tendinous fibres that lie obliquely in aponeurotic sheets, allowing for changes in the shape of the abdominal wall, for example during respiration. However, the midline can change only in length and breadth, an increase in one necessitating a decrease in the other. During abdominal distension, the linea alba must increase in both dimensions, the resulting tearing of fibres possibly leading to the development of an epigastric hernia.
The majority of epigastric hernias (probably 75%) are asymptomatic. Typical symptoms, if present, include vague upper abdominal pain and nausea associated with epigastric tenderness. The symptoms tend to be more severe when the patient is lying down, attributed to traction on the hernial contents. Pain on exertion localised to the epigastrium is also a common symptom. Incarceration is common, and strangulation of pre-peritoneal fat or omentum results in localised pain and tenderness. Incarceration or strangulation of intra-abdominal viscera is extremely rare, the symptoms obviously depending on the incarcerated organ.
The presence of a midline mass on physical examination usually confirms the diagnosis. In obese patients, palpation of the mass may be difficult and confirmation of the diagnosis by ultrasound or computed tomography may be helpful.
Epigastric hernias are rare in infants and children, and asymptomatic hernias in children under the age of 10 years may resolve spontaneously. The decision for surgical intervention depends on the presence and severity of symptoms.
Small solitary defects may be approached with either a vertical or transverse incision in the midline, centred over the hernia. For larger hernias, if the defects are multiple or in the emergency setting when a strangulated viscus is suspected, a vertical incision is preferred. The hernia and its contents are dissected free of the surrounding tissues and, if present, the hernial contents examined and dealt with appropriately. If the defect is small (< 2 cm), repair by primary suture closure using non-absorbable material is usually sufficient. The orientation of the suture closure remains controversial, some surgeons preferring a vertical closure and others a horizontal orientation. There are very few data to support one technique over the other and probably the direction resulting in the least tension is the most appropriate. If the defect is large (> 6 cm2), or occurs within a divarification of the recti, the hernia should be repaired with prosthetic mesh. This technique is described later in the chapter when considering incisional hernias. The technique applied to intermediate-sized hernias is controversial and suture or mesh techniques are both currently deemed acceptable. Laparoscopic repair of epigastric hernias9 was first described in 1993 and the technique has grown in popularity. The author prefers an open technique under local anaesthetic whenever possible for smaller hernias (defect < 2 cm), suture or mesh depending on the quality of the tissues, and the laparoscopic approach for larger, multiple, recurrent hernias, or hernias in the obese. At laparoscopic repair, it is important to take down the falciform ligament and remove any pre-peritoneal fat above the linea alba, otherwise the ‘hernia’ may still be palpable following the alleged repair.
Complication rates are low and most are the usual complications associated with abdominal wall incisions (haematoma, infection). There are very few data on recurrence rates, historical series reporting rates around 7%.10 In perhaps 50% of patients, however, the recurrence probably represents the persistence of a second hernia or area of weakness overlooked at the initial procedure. The laparoscopic technique avoids this problem because all fascial defects are visible laparoscopically if adequate dissection is carried out.
Umbilical and para-umbilical hernias
There are several distinct types of hernia that occur around the umbilicus: congenital (omphalocele), infantile, para-umbilical and adult umbilical hernias.
Congenital Umbilical Hernias
A congenital umbilical hernia occurs when the abdominal viscera herniate into the tissue of the umbilical cord. Normally, the gut returns to the abdominal cavity at 10 weeks of gestation. If this fails to occur, normal rotation and fixation of the intestine are prevented, the umbilicus is absent and a funnel-shaped defect in the abdominal wall is present through which viscera protrude into the umbilical cord. The abdominal wall defect may vary in size from no larger than an umbilical stump to a defect that appears to involve the entire abdominal wall. Congenital umbilical hernia occurs in 1 in 5000 births and is associated with other serious congenital anomalies.
Congenital umbilical hernia may be diagnosed in utero or at birth. On ultrasound examination, foetal abdominal wall defects are not subtle and may be visualised as early as 15 weeks of gestation. The management is surgical correction and one of the most important contributors to the morbidity and mortality of isolated abdominal wall defects is the delay between delivery and appropriate surgical repair. Antenatal knowledge of the existence of a congenital hernia can allow for the birth of the child at a tertiary care institution with the appropriate neonatal and paediatric surgical expertise (see also Chapter 12).
Surgical correction should only be undertaken in specialised centres. If the diagnosis is made prenatally, the mother should be transferred to such a centre for delivery. If the diagnosis only becomes apparent at birth, the baby should be kept warm and hydrated, and the sac handled with care to avoid rupture or twisting of the sac. The sac should be wrapped in moist sterile gauze and covered with impervious plastic sheeting or aluminium foil. Mother and baby should then be transferred as soon as feasible to a tertiary centre for further management.
Infantile Umbilical Hernias
Infantile umbilical hernias occur when the umbilical vessels fail to fuse with the urachal remnant and umbilical ring. It presents with a protrusion of the umbilicus, usually at the superior margin of the ring. The infantile hernia, as opposed to the congenital type, is always covered by skin. It is the third most common surgical disorder in children, occurring in approximately one in five live births.
Clinically, the commonest presenting ‘symptom’ is the cosmetic appearance, the hernia resulting in a cone-like protrusion of the umbilicus that bulges every time the child cries or strains. Infantile umbilical hernias rarely enlarge over time and 90% disappear by the time the child is 2 years of age, although they are unlikely to close spontaneously if they persist to the age of 5 years.11 Spontaneous resolution of umbilical hernias appears to be directly influenced by the size of the umbilical ring. If, at the age of 3 months, the hernia has a fascial ring of < 0.5 cm, 96% heal spontaneously within 2 years. Defects that have a fascial diameter > 1.5 cm are unlikely to heal spontaneously. Complications of umbilical hernias are rare, occurring in approximately 5%, and include strangulation of the omentum, strangulation of the intestine and evisceration.
Management of the infant with an umbilical hernia is expectant. The majority will resolve spontaneously without surgical correction. The indications for surgery in children less than 2 years of age are the development of complications or tenderness over the site of the hernia. There is no consensus on the appropriate timing of herniorrhaphy in older children but generally repair is performed before school/nursery to avoid the child becoming self-conscious of the umbilical protrusion.
Operative Details: Elective repair of infantile umbilical hernia is performed on an outpatient basis under general anaesthesia. A curvilinear incision is made within a skin fold on the inferior aspect of the hernia. The sac is then encircled by blunt dissection. If there is any concern regarding the contents of the sac, the sac should be opened on its caudal aspect, as abdominal contents usually adhere to the fundus of the sac. Once dealt with appropriately, the contents should be reduced and the incision continued to the cephalic aspect of the sac. If the sac is empty, the fundus may simply be disconnected from the umbilicus and reduced intact. Repair is by simple fascial apposition using horizontal mattress sutures of absorbable material. While the Mayo (‘vest-over-pants’) technique of umbilical hernioplasty is frequently taught, there is no evidence that the results are any better than simple apposition of the fascial edges. The umbilicus is refashioned by leaving a small button of the fundus of the sac attached to the inner surface of the cicatrix and tacking it down to the area of fascial repair.
Complications of umbilical hernioplasty are rare, but include seroma or haematoma formation and infection. Recurrence is possible if large defects are closed under tension or if an associated para-umbilical hernia is overlooked.
Para-umbilical hernias are acquired hernias and occur in all age groups. They occur secondary to disruption of the linea alba and generally occur above the umbilical cicatrix. Aetiological factors include stretching of the abdominal wall by obesity, multiple pregnancy and ascites. Para-umbilical hernias are more common in patients over the age of 35 years and are five times more common in females.
Clinically, para-umbilical hernias are frequently symptomatic. Patients complain of intermittent abdominal pain (possibly caused by dragging on the fat and peritoneum of the falciform ligament) and, when the hernial sac contains bowel, colic resulting from intermittent intestinal obstruction. The hernia tends to progress over time and intertrigo and necrosis of the skin may occur in patients with large dependent hernias. Such symptoms are a good indication for surgery.
It is important to distinguish para-umbilical hernias from true umbilical defects as the latter may resolve spontaneously in the young, whereas the former require surgical correction. Umbilical hernias classically produce a symmetric bulge with the protrusion directly under the umbilicus. This is in contrast to para-umbilical hernias, where about half the fundus of the sac is covered by the umbilicus and the remainder is covered by the skin of the abdomen directly above or below the umbilicus(Fig. 4.3). Para-umbilical hernias do not resolve spontaneously and have a high incidence of incarceration and strangulation; therefore, surgical repair is nearly always indicated.
FIGURE 4.3 Clinical photograph of a para-umbilical hernia. Note the swelling of the right groin of an associated right inguinal hernia – a common finding consistent with a generalised collagen disorder.
Operative Details: For solitary hernias separated from the umbilicus, a transverse incision over the hernia produces the best exposure. In patients with a para-umbilical and umbilical hernia, a midline incision may provide better access. Similarly, if multiple fascial defects are present or there is concern about the integrity of visceral contents of the sac, a vertical incision may be better employed. If the defect simply contains pre-peritoneal fat, this may be reduced. In patients with strangulated or ischaemic pre-peritoneal fat, it is best excised. If there is a sac present, it should be dissected free from the fascial edges, opened and the contents examined. Once the contents have been dealt with appropriately, they may be reduced and redundant sac excised. There is no requirement to close the peritoneum but some authors recommend transfixing the neck of the sac once the contents have been reduced. Repair is performed by fascial apposition either transversely or longitudinally, depending on the defect and the direction of least tension. As this is an acquired defect, non-absorbable sutures are recommended. Indeed, the author usually creates a pre-peritoneal pocket, inserting a 5 cm × 5 cm square (minimum size – bigger if necessary) mesh and closing the fascia over this. The classic Mayo approach12 overlaps the edges, but there has never been any demonstration that the bursting strength of the wound is improved by imbrications and may actually be impaired to a degree proportional to the amount of overlapping and tension. For larger para-umbilical hernias, with a neck size > 3 cm (or smaller hernias in an obese patient), it is the author's preference to repair these laparoscopically and very large hernias with a neck size > 8 cm by an open sublay technique (described later).
The overlying umbilical skin need not be excised unless it is macerated or infected, although the cosmetic appearance is often enhanced by judicious removal of excess skin and subcutaneous fat. All patients should be warned that it might be necessary to excise the umbilicus. If a new umbilicus is to be created, care should be taken as recurrences may occur at the point on the linea alba where the new umbilicus is fixed to the fascia.
Complications include the development of seromas, haematomas and infection. Sealed suction drains may be employed in the retromuscular and subcutaneous planes to avoid the development of large seromas. In addition to local problems, these patients may have respiratory and cardiovascular complications.
Adult Umbilical Hernias
Umbilical hernias in adults represent a spectrum of conditions from the partially unfolded cicatrix to huge dependent sacs. The umbilicus may become partially unfolded in patients with acute abdominal distension. Persistent elevation of intra-abdominal pressure eventually results in the umbilical cicatrix giving way and the development of an umbilical hernia. Although uncommon, causes include ascites from cirrhosis, congestive cardiac failure or nephrosis. Patients undergoing peritoneal dialysis also have a high incidence of these hernias. Management should be non-operative where possible, as the majority of these patients have serious underlying pathology. Operative repair is not indicated unless the hernia incarcerates or becomes extremely large and the overlying skin is thinned down to such an extent that spontaneous rupture is possible.
Umbilical hernias in adults do not represent persistence of infantile hernias but are indirect herniations through an umbilical canal, which is bordered by umbilical fascia posteriorly, the linea alba anteriorly and the medial edges of the two rectus sheaths on each side. They have a tendency to incarcerate and strangulate and do not resolve spontaneously. Umbilical hernias in adults have a high morbidity and mortality. Over 90% occur in females and almost all patients are obese and multiparous.
The clinical presentation, management and complications of adult umbilical hernia are very similar to those of para-umbilical hernia, as described above.
The anatomy of the inguinal region is complex. The inguinal canal is approximately 4 cm in length and is located just above the inguinal ligament between the internal and external rings. The inguinal canal allows passage of the spermatic cord into the scrotum, along with the testicular, deferential and cremasteric vessels. The superficial ring is a triangular aperture in the aponeurosis of the external oblique and lies about 1 cm above the pubic tubercle. The ring is bounded by a superomedial and an inferolateral crus joined by criss-cross intercrural fibres. Normally, the ring will not admit the tip of the little finger. The deep ring is a U-shaped condensation of the transversalis fascia and it lies about 1 cm above the inguinal ligament, midway between the pubic tubercle and the anterior superior iliac spine. The transversalis fascia is the fascial envelope of the abdomen and the competency of the deep inguinal ring depends on the integrity of this fascia.
The anterior boundary of the inguinal canal comprises mainly the external oblique aponeurosis with the conjoined muscle laterally. The posterior boundary is formed by the fascia transversalis and the conjoined tendon (internal oblique and transversus abdominus medially). The inferior epigastric vessels lie posteriorly and medially to the deep inguinal ring. The superior boundary is formed by the conjoined muscles (internal oblique and transversus) and the inferior boundary by the inguinal ligament.
An indirect hernia travels down the canal on the outer (lateral and anterior) side of the spermatic cord. A direct inguinal hernia comes out directly forwards through the posterior wall of the inguinal canal. While the neck of an indirect hernia is lateral to the epigastric vessels, the direct hernia usually emerges medial to these vessels, except in the saddle-bag or pantaloon type, which has both a lateral and a medial component (Fig. 4.4).
FIGURE 4.4 Laparoscopic totally extraperitoneal (TEP) view of the right groin with a direct inguinal hernia (DH) lying medial to the inferior epigastric vessels (IE), above the inguinal (IL) and lacunar (LC) ligaments. The pubic bone (P), iliac vessels (IV), vas and vessels (VV) are also seen. The positions of a femoral hernia (FH) and indirect inguinal hernia (IH) are also marked.
Inguinal Hernia In Infants And Children (See Also Chapter 12)
Repair of congenital inguinal hernia is the most frequently performed operation in the paediatric age group. Although inguinal hernias can present at any age, the peak incidence is during infancy and childhood. About 3–5% of full-term infants may be born with a clinical inguinal hernia. Between 80% and 90% of paediatric hernias occur in boys, about one-third of the hernias presenting in the first 6 months of life. Congenital inguinal hernias have a 15% bilateral presentation.
Examination of the inguinal area for a hernia may show an obvious bulge at the site of the external ring or within the scrotum that can often be gently reduced. However, the bulge may only be seen during severe straining, such as with crying or defecation. If the infant is old enough to stand, he or she should be examined in both the supine and standing positions. If not, the parent can hold the infant upright so that the surgeon can closely observe the inguinoscrotal area. Sometimes, photographs taken by the parent when a swelling appears can aid in the diagnosis in the difficult case. It is essential to make sure that the testis is within the scrotal sac to avoid mistaking a retractile testis for a hernial bulge. The presence of an empty scrotum should alert the examining surgeon to a possible undescended or ectopic testis, which is associated with an inguinal hernia in more than 90% of patients. Although routine orchidopexy is usually delayed until the child is 1 year of age, a coexisting symptomatic hernia should be promptly repaired and orchidopexy accomplished at the same time.
Inguinal hernias in infants and children are prone to incarcerate, with the overall rate being 12%.13 Incarceration is most common in the first 6 months of life, when more than half of all instances are observed. An incarcerated hernia usually presents as an acute tender mass in the inguinal canal. The mass may protrude beyond the external inguinal ring or into the scrotum. The skin over the mass may be discoloured, oedematous, erythematous or blue. Strangulation, characterised by abdominal distension, vomiting, failure to pass faecal material, tachycardia and radiological evidence of small-bowel obstruction, demands emergency operative intervention for relief of obstruction, intestinal salvage and hernia repair. In contrast to the adult with an incarcerated hernia, in children testicular ischaemia is far more common than intestinal ischaemia, and it is therefore appropriate to be aggressive about reducing the hernia (see Chapter 12).
In general, hernias in children and particularly infants should be managed by experienced paediatric surgeons (see also Chapter 12). However, this is not always possible depending on geography and availability. In these circumstances the general surgeon on call may be required to manage these patients. As most (80%) incarcerated hernias in children may be managed initially by non-operative measures, which include sedation, and then gentle reduction when the baby is quiet, exploration may be safely delayed for about 24–48 hours, allowing, if possible, a more experienced paediatric surgeon to become involved. However, if the hernia remains irreducible at this stage, emergency repair is indicated. The complication rate is approximately 20 times greater after emergency repair for incarcerated hernia than after elective procedures.14 It is therefore worthwhile to reduce the hernia whenever possible and perform an elective procedure within 24–48 hours of the reduction. The high risk of incarceration in the paediatric age group makes the presence of an inguinal hernia an indication for surgical repair.
Operative Details: Surgical access is achieved through a short (2–3 cm) transverse incision in the lowest inguinal skin crease. The superficial fascia (Scarpa's fascia) is incised and the external oblique fascia identified. The aponeurosis is traced laterally to identify the inguinal ligament and the exact location of the external inguinal ring identified. Although some surgeons advocate repair through the external ring (Mitchell Banks technique15), an alternative approach is to incise the external oblique fascia in the long axis of its fibres, perpendicular to the external inguinal ring. This exposes the cremasteric muscle and fascia, which envelop the cord structures.
The hernial sac is always located in an anteromedial position in relation to the cord and gentle blunt dissection of the cremasteric fibres usually brings the sac into view. The sac is elevated with a haemostat and the cremasteric fibres carefully freed from the anterior and lateral aspects. Retraction of the sac medially allows identification of the spermatic vessels and vas deferens, and these structures may be carefully teased away from the sac in a posterolateral direction. Injection of 1–2 mL of saline into the cord may help to define the planes of separation. The vas itself should not be grasped and the floor of the canal not disturbed. Once the end of the sac has been freed, the dissection of the sac is carried superiorly to the level of the deep inguinal ring. If the sac extends down into the scrotum, it may be divided once the cord structures are identified and protected. The base of the sac may then be gently twisted to reduce any fluid or viscera into the peritoneal cavity. The base of the sac should be suture ligated with an absorbable suture and, once the suture is cut, the peritoneal stump should retract proximally through the deep inguinal ring. Free ties should not be used because of the risk of them becoming dislodged if abdominal distension occurs. Absolute haemostasis is essential to prevent postoperative haematoma formation. The position of the testis within the scrotum should be confirmed to avoid iatrogenic entrapment within the inguinal canal. There is an increasing role for laparoscopic hernia repair in infants and young children.14
An emergency operation is required for patients with an incarcerated hernia, with toxicity and obvious intestinal obstruction or after failed attempts at reduction. As previously mentioned, a paediatric surgeon should be involved in all cases if possible as this can be a difficult undertaking. After appropriate resuscitation, prophylactic antibiotics and insertion of a nasogastric tube, the operation begins with preparation of the whole abdomen in case laparotomy is required. An inguinal incision is utilised and the incarcerated intestine carefully inspected for viability once the obstruction at the internal ring is relieved. A rapid return of pink colour, sheen, peristalsis and palpable or visible pulsations at the mesenteric border should be observed. If there is any question regarding intestinal viability, resection and anastomosis should be carried out and hernial repair accomplished.
In certain circumstances, the incarcerated intestine may reduce during surgical manipulation, before the intestine has been visualised. However, such spontaneous reduction of infarcted bowel is very rare. Laparoscopy through the hernial sac can be undertaken if there are serious concerns regarding bowel viability. Surgery for incarcerated hernia may be difficult because of oedema, tissue friability and the presence of the mass, which may obscure the anatomy. The gonad should be carefully inspected because it may become infarcted by vascular compression caused by the incarcerated intestine. The undescended testis is more vulnerable to this complication in the presence of incarcerated intestine.
Complications may be divided into intraoperative and postoperative categories. Intraoperative complications include: division of the ilioinguinal nerve, which can be avoided if the external oblique fascia is elevated before incision; division of the vas deferens, which should be repaired with interrupted 7–0 monofilament sutures; and bleeding, which is usually secondary to needle-hole injury and can usually be controlled with withdrawal of the suture and the application of pressure.
Postoperative complications include wound infection, scrotal haematoma, postoperative hydroceles and recurrence. The wound infection rate is low (1–2%) and recurrence rates of less than 1% are reported, 80% of recurrences being noted within the first postoperative year. The major causes of recurrence in infants and children include: (i) a missed hernial sac or an unrecognised tear in the peritoneum; (ii) a broken suture ligature at the neck of the sac; (iii) injury to the floor of the inguinal canal, resulting in the development of a direct inguinal hernia; (iv) severe infection in the inguinal canal; and (v) increased intra-abdominal pressure, as is noted in patients with ascites after ventriculoperitoneal shunts, in children with cystic fibrosis, after previous operation for incarceration and in patients with connective tissue disorders. Although failure to repair a large internal inguinal ring is a possible (and very occasional) cause of recurrence, attempts to tighten the internal ring at the time of the first repair by approximating the transversalis fascia medial to the inferior epigastric vessels risk compromising the blood supply to the testicle and should be avoided where possible. Simple excision of the sac is all that is required in most patients. Re-operations for recurrent inguinal hernia may be a technical challenge and a pre-peritoneal approach is an extremely useful alternative for recurrent hernias.
Adult Inguinal Hernias
Inguinal hernias are more frequent in males, with a male to female ratio of 12:1. The peak incidence is in the sixth decade and 65% are indirect in type. Right-sided inguinal hernias are slightly more common than left-sided, 55% occurring on the right. Bilateral hernias are four times more common in direct than indirect forms.
The pathogenesis of groin hernias is multifactorial. It was initially believed that persistence of a patent processus vaginalis into adult life was the predisposing factor for indirect inguinal hernia formation. However, post-mortem studies have shown that 15–30% of adult males without a clinically apparent inguinal hernia have a patent processus vaginalis.16 Similarly, review of the contralateral side in infantile inguinal hernias reveals a patent processus vaginalis in 60% of neonates and a contralateral hernia in 10–20%. During 20 years of follow-up after infantile hernia repair, only 22% of men will develop a contralateral hernia.
It is therefore apparent that the problem of indirect inguinal hernia is not simply one of a congenital defect. The high frequency of indirect inguinal hernia in middle-aged and older people suggests a pathological change in connective tissue of the abdominal wall to be a contributory factor,1 as discussed earlier.
The essential goal of hernia repair is to restore the functional integrity of the laminar musculo-aponeurotic structure of the groin region and the musculo-aponeurotic fenestration, which allows the vessels to the genitalia to penetrate this structure. It is beyond the scope of this chapter to review the history of the various repair techniques that have been previously employed and are now mainly historical. However, Fig. 4.5 illustrates how the popularity of suture and mesh techniques has changed in the Lothian region of Scotland in the last 20 years. Only the latest techniques (i.e. prosthetic repairs) will be considered here.
FIGURE 4.5 Changing patterns in suture, mesh and laparoscopic inguinal hernia repair in the Lothian Region, Scotland.
Tension-Free Prosthetic Mesh Repair: Lichtenstein first described the technique of tension free repair of groin hernia, which now bears his name.17 Tension-free repair of primary groin hernias may be performed as an outpatient procedure under local anaesthesia, although in the UK open mesh repair is still more commonly performed under general anaesthetic.
Once the local anaesthesia has been administered (typically a mixture of 0.5% bupivacaine and 1% lignocaine) along the line of the proposed incision, a cut is made in the groin-crease and a window established through the subcutaneous tissues including Scarpa's fascia at the lateral end of the wound, exposing the external oblique aponeurosis. The window is increased in size to expose the medial end of the external oblique aponeurosis, the inguinal ligament and the superficial ring. Additional anaesthetic is then injected under the external oblique aponeurosis, following which a small incision is made in the external oblique along the line of the fibres, approximately 2 cm above the inguinal ligament. The edges are carefully lifted with haemostatic forceps to avoid damage to the ilioinguinal nerve. The external oblique aponeurosis is then opened along a line from the incision to the superficial ring and the contents of the inguinal canal gently separated from it. After a self-retaining retractor has been inserted under the edges of the external oblique aponeurosis, the spermatic cord is mobilised utilising the avascular space between the pubic tubercle and the cord itself to avoid damage to the floor of the canal, injury to the testicular blood flow and crushing of the genital nerve, which always lies in juxtaposition to the external spermatic vessels (Fig. 4.6).
FIGURE 4.6 Open right inguinal hernia repair. External oblique has been opened. Medial is to the right of the picture with superior at the top. Note the iliohypogastric (IH), ilioinguinal (II) that splits into two branches, and the small genitor-femoral nerve (GF) lying inferiorly. Clinical photograph used with permission of Mr Martin Kurzer, London, UK.
In order to thin out the spermatic cord and remove any lipoma present, the cremaster fibres are incised longitudinally at the level of the deep ring. Complete excision of the cremaster fibres from the spermatic cord is unnecessary and may result in damage to the vas deferens, increasing the likelihood of postoperative neuralgia and ischaemic orchitis. Indirect hernial sacs are opened and digital exploration performed to detect any other defects or the presence of a femoral hernia. Lichtenstein states that the sac may be simply inverted into the abdomen without excision, suture or ligation, which he feels is unnecessary and may contribute to postoperative discomfort.17 However, it is the author's practice to suture ligate any but the smallest hernial sacs at the level of the deep ring and excise any redundant peritoneum. To prevent postoperative hydrocele formation, complete scrotal sacs are transected at the midpoint of the canal, with the distal section left open and in situ. If performing the procedure under local anaesthetic, handling of the sac at this stage can cause pain and often further local anaesthetic to the sac area in the region of the deep ring is required.
In the event of a large direct hernia, the sac (transversalis fascia) is invaginated with an imbricating suture to achieve a flat surface over which to lay the prosthetic mesh. The external oblique aponeurosis is separated from the underlying internal oblique muscle at a point high enough to accommodate a mesh measuring around 11 cm × 6 cm. This size will vary depending on the size of the patient and the size of the hernial defect.
The mesh is trimmed as appropriate so that the patch overlaps the internal oblique muscle and aponeurosis by at least 2 cm above the border of the Hesselbach triangle. The medial portion of the mesh is rounded to the shape of the medial corner of the inguinal canal. The mesh is sutured to the aponeurotic tissue over the pubic bone, overlapping the bone to prevent any tension or weakness at this critical point, but ensuring the periosteum is not caught in the suture as this is believed to be a good source of chronic pain. The medial part of the mesh should extend at least 2 cm medial to the pubic tubercle to reduce the risk of medial recurrence. The same suture is continued along the lower edge, attaching the mesh to the shelving portion of the inguinal ligament to a point just lateral to the deep ring with a continuous suture.
A slit is made at the lateral end of the mesh, creating a wider tail above the cord and a narrower one below the cord. This manoeuvre positions the cord between the two tails of the mesh and avoids the keyhole opening, which is less effective at preventing recurrence. The upper edge of the patch is sutured to the internal oblique aponeurosis using a few interrupted sutures or widely spaced continuous suture. Sharp retraction of the upper leaf of the external oblique aponeurosis from the internal oblique muscle is important because it provides the appropriate amount of laxity for the patch. When the retraction is released, a true tension-free repair is taken up when the patient strains on command during the operation (if under local anaesthetic) or resumes an upright position afterwards. Using a single non-absorbable monofilament suture, the lower edges of the two tails are fixed to the shelving margin of the inguinal ligament just lateral to the completion knot of the lower continuous suture. This creates a new deep ring of mesh (Fig. 4.7). Some surgeons simply suture the lower edge of the upper tail to the upper edge of the lower tail.
FIGURE 4.7 Left inguinal hernia repair. Mesh in place. Note continuous suture attaching inferior edge of mesh to inguinal ligament and mesh fish-tailed laterally to create a new deep ring. Cord structures and ilioinguinal nerve are intact. The mesh is lying flat and ‘tension’ free.
The excess patch is trimmed on the lateral side, leaving 3–4 cm beyond the deep ring. This is tucked underneath the external oblique aponeurosis and the external oblique aponeurosis closed with a continuous suture. Unrestricted activity is encouraged and patients are expected to return to their normal activity 2–7 days after surgery.
In the past few years, there has been an explosion in different mesh types for the open repair of inguinal hernias. The plug and patch utilises a cone-shaped mass of mesh that can be inserted, tip side inwards, into either the deep or superficial rings, depending on the type of hernia. A flat mesh is then placed over the plug akin to the Lichtenstein technique. The prolene hernia system is two flat meshes secured together by a small cyclinder of mesh. The aim is to insert one mesh into the pre-peritoneal space and the other is secured akin to the Lichtenstein technique. There is also the open pre-peritonel approach with the Kugel patch, for example. All these alternatives report good results in the hands of experts, but the open flat mesh technique in its various forms, akin to the Lichtenstein technique, remains the commonest technique in Western countries to date. It is also the author's prejudice that if a mesh is to be inserted into the pre-peritoneal space, it makes sense to do this under direct vision using a laparoscope rather than using a largely blind, blunt finger dissection technique.
Laparoscopic Repair: The alternative to an open operation is a laparoscopic approach. Ger is credited with the first laparoscopic approach to hernia, repairing indirect hernias with a stapling instrument developed for this purpose.18,19 In parallel, Gazayerli described a suture repair technique through a transabdominal approach, approximating the transversus abdominis aponeurotic arch and the iliopubic tract.20 After the repair is completed, the peritoneum is re-approximated. Since the early 1990s, laparoscopic hernia repair has evolved from simple closure of a small indirect hernia, through the placement of mesh plugs and a small mesh patch over the internal ring, to the current use of large pieces of prosthetic mesh to reinforce the lower abdominal wall.
The rationale for the use of large mesh sheets placed into the pre-peritoneal space was based on the surgical experience of the open pre-peritoneal hernia repair, especially in the treatment of recurrent hernias.21 Although a variety of laparoscopic repairs have been described, they can be categorised in general according to the approach used to expose the defect. Three exposures are used: the intraperitoneal approach, in which the prosthesis is placed as an onlay graft over the peritoneum; the transabdominal pre-peritoneal (TAPP) repair; and the totally extraperitoneal (TEP) repair.
Intraperitoneal prosthetic repair: In the intraperitoneal repair with an onlay graft, the prosthesis is placed within the peritoneal cavity. The technique is well described by Toy and Smoot.22Compared to the TAPP and TEP approaches, it has the advantages of being less time-consuming to perform and requires no dissection of the pre-peritoneal space. It has the disadvantage of leaving the prosthetic material exposed within the peritoneal cavity and has a higher recurrence rate. It is the author's view that this operation is very much an operation of last resort, when other open or laparoscopic techniques have failed. It is possible that when better non-stick meshes become available, combined with glue fixation, this technique may gain in popularity.
Transabdominal pre-peritoneal prosthetic repair: TAPP repair is one of the most popular approaches used for laparoscopic herniorrhaphy, particularly in Europe. The abdomen is insufflated with carbon dioxide and the laparoscope introduced through an umbilical incision. Two accessory trocars, placed well above and slightly medial to the anterior superior iliac spines, are used to provide access for the dissecting instruments and the stapler. After both groins have been inspected, a second incision is made in the pelvic peritoneum several centimetres above the hernia defect, typically in line with the level of the anterior iliac spine, and the peritoneum then peeled away to expose the hernia defect. The peritoneum is dissected bluntly away from the abdominal wall, allowing the hernia sac to be inverted and dissected free of adherent tissue. Pre-peritoneal fat is removed to allow identification of the transversus abdominis arch, the pubic tubercle, the iliopubic tract and Cooper's ligament. A prosthetic mesh of approximately 10 cm × 15 cm is inserted and manipulated into position so that it covers the entire myopectineal orifice. Some surgeons fix the mesh in place with staples, sutures or glue, although there is little evidence to support such practices. The peritoneum is closed over the mesh with staples or sutures. This approach has the advantage of permitting inspection of the abdomen in general, and of the opposite side in particular, enabling bilateral repairs to be performed if necessary. In addition, exposure is usually excellent. The disadvantage is that a wider dissection is required to accommodate the mesh than is used in the intraperitoneal onlay procedure. In addition, the intra-abdominal incision presents the possibility of injury to intraperitoneal structures and a second peritoneal incision in the groin increases the potential for adhesion formation and late bowel obstruction.
Totally extraperitoneal prosthetic repair: TEP repair is a laparoscopic adaptation of the open posterior pre-peritoneal approach first described by Annandale.23 The laparoscope is introduced into the pre-peritoneal space through an infra-umbilical incision. The pre-peritoneal space is dissected towards the symphysis pubis, Cooper's ligament and the iliac vessels with a blunt instrument or space-making balloon. Carbon dioxide is insufflated into the pre-peritoneal space to maintain exposure. Care must be taken to avoid entering the peritoneum; if this occurs, loss of pressure in the pre-peritoneal space can result, making exposure more difficult. A venting Verres needle in the right iliac fossa will usually resolve this problem, or alternatively a structural balloon attached to the umbilical port will help to keep the pre-peritoneal space open. Two additional 5-mm ports are inserted, either in the right and left iliac fossa, after extending the dissection laterally or in the midline below the umbilicus. Direct hernial sacs usually reduce with ease, but an indirect hernial sac may need more work. The key landmark here is the vas. The indirect hernial sac lies above and lateral to the vas, taking the dissection away from the iliac vessels, preventing their inadvertent injury. A mesh of minimum size 10 cm × 15 cm is used to cover all the inguinal and femoral myopectineal orifices, ensuring good cover laterally and superiomedially. As with TAPP repairs, there is now good evidence that suturing, tacking or stapling of mesh does not reduce the risk of hernia recurrence but is a cause of postoperative chronic pain.24 The author does occasionally tack the mesh, confined mainly to the patient with a very large direct hernial defect or when there has been more bleeding than usual, especially patients on aspirin. In all circumstances tacks are placed medial to the inferior epigastric vessels and superior to the pubic bone only. More recently, the author has attempted laparoscopic suture closure of large direct inguinal hernias with a non-absorbable suture rather than using tacks. The TEP approach avoids the risks of entering the peritoneal cavity and subsequent intraperitoneal adhesion formation.
There is little evidence to support TEP versus TAPP and the technique used is largely down to the individual surgeon. The author's preference is the TEP approach, with the TAPP approach reserved for recurrence after a previous TEP or open intraperitoneal operations.
Laparoscopic repair of ingiunal hernias causes less acute and chronic pain, thus earlier return to work, less infection, fewer wound complications and less numbness than the open operation. It is currently the preferred technique recommended by the National Institute for Clinical Excellence (NICE) for recurrent inguinal hernias and bilateral primary inguinal hernias, and an alternative operation for primary unilateral hernias.25
Complications of herniorrhaphy include recurrence, urinary retention, ischaemic orchitis and testicular atrophy, wound infection and nerve injuries (neuromas of the ilioinguinal or genitofemoral nerves). A wide variation in recurrence rates is reported in the literature, depending on both the surgical technique employed and the method and length of follow-up (questionnaire, physical examination, etc.). In general, papers comparing mesh to suture repair note lower recurrence rates in the mesh group.26 Nevertheless, the percentage of recurrent to primary hernia repair has remained largely constant in Lothian, Scotland over the past 30 years at around 10%. Perhaps the only role for suture repair remains in the adolescent age group, where perhaps a herniotomy alone is insufficient and the risks of mesh insertion not merited. There has been a suggestion that mesh repairs in the groin can affect fertility in males.27 This is a very controversial area, as the occurrence of a hernia per se in the young is associated with reduced fertility. There is no convincing evidence to support the view that a mesh repair affects fertility except when there is obviously direct trauma to the vas or vessels to the testicle.
The complication that is becoming the benchmark for comparing hernia repairs is the incidence of chronic pain, rather than recurrence rate. Risk factors for chronic pain include nerve damage, preoperative pain in the hernia, young age, pain at other sites of the body, postoperative complications and psychosocial features.28 Pain response to a standardised heat stimulus appears to be a useful tool in assessing risk of postoperative chronic pain.29
Suture, mesh or laparoscopic repair?
The Shouldice technique using suture repair rather than mesh is still carried out in many centres worldwide and numerous publications have reported recurrence rates of 1–2%.30 To date, the Lichtenstein tension-free repair has the largest number of published repairs with the lowest recurrence rates. Lichtenstein and colleagues published a multicentre series of 22 300 hernioplasties performed by this technique, with a recurrence rate of 0.77%.31
The 2004 NICE report commented on 37 randomised controlled trials that compared laparoscopic with open mesh repair of inguinal hernias in a total of 5560 participants.25 The report summarised these results, stating that the laparoscopic repair as compared to an open repair was associated with less acute pain and thus a quicker return to daily activites and work, fewer wound complications such as haematoma, seroma and infection, and less risk of chronic pain. There was a similar recurrence rate and a similar risk of major vessel, bowel or bladder injury (except for a slightly higher risk for the TAPP repair). However, the laparoscopic repair took longer to perform and was a more expensive option. The cost of open surgery has to be set against the price of open surgery for the patient and society, namely more acute and chronic pain, more time off work and more wound complications. This is borne out by a cost–benefit analysis using the same data as the 2004 NICE report.32 Unilateral hernia open flat mesh repair was the least costly option, but it provided fewer quality-adjusted life-years compared to both TAPP and TEP. Also, laparoscopic repair for bilateral hernias reduces both operating times and convalescence period, equating to greater cost-effectiveness. In addition, repair of an occult hernia on the other side may also be performed, enhancing the benefit of the laparoscopic procedure.
Mesh repair using the Lichtenstein technique has the lowest worldwide recurrence rate for primary inguinal hernias. The laparoscopic repair is associated with less early and late pain, earlier return to normal activities and work, but is more expensive. It is, however, the preferred technique for the repair of recurrent and bilateral hernias.25,32
Recent publications now demonstrate that laparoscopic repairs, whether unilateral or bilateral, can be performed more quickly than open repair.33,34 The only downside to laparoscopic hernia surgery is the need for general anaesthesia. While small numbers have been done under local or regional techniques, these have been confined to young fit patients, for whom avoidance of a general anaesthetic is not necessary. Nevertheless, in many Western countries open inguinal hernias are still predominantly repaired under general anaesthetic.
Inguinal hernia arises as a design fault, both anatomically and at the level of collagen metabolism, so there is every reason why it should be a bilateral disease. Furthermore, clinical assessment of bilateral or unilateral hernia has a false positive and negative rate of around 10%. The rate of development of a contralateral inguinal hernia following open repair is around 25% at 10 years.26 The Edinburgh experience is that time from first repair to contralateral repair in the laparoscopic era is about half the time compared to open hernia repair. It could be argued that the larger mesh inserted laparoscopically places more strain on the contralateral side. An alternative hypothesis is that following laparoscopic repair, patients are more likely to volunteer for repair of the contralateral side as the operation is less painful. It is thus the author's practice to offer the majority of patients a bilateral laparoscopic repair, unless the laparoscopic approach is contraindicated and the patient unfit or elderly.
Recurrent Inguinal Hernias
The repair of recurrent inguinal hernia remains a common operation and there is now some evidence to suggest that the increasing use of mesh may be having a small effect in reducing the number of recurrent hernia repairs26,35 (see section on prophylactic hernia repair at the end of this chapter). As a result there is little role now for suture repair of recurrent inguinal hernias, and a re-recurrence rate of 30% for the Bassini technique has been reported.36 The McVay procedure and transversalis repair are not commonly employed and the results are probably of historic interest only. In centres where alloplastic material is unavailable or too expensive for routine use, the Shouldice technique is probably the technique of choice.37
Prosthetic mesh repair of recurrent inguinal hernias
The Lichtenstein repair remains the commonest operation for recurrent inguinal hernias. Rate of re-recurrence depends to an extent on the length of follow-up, but is typically under 10%. Since its introduction, excellent results have been reported with the mesh plug method.38 The transinguinal pre-peritoneal prosthetic repair/Rives procedure tends to be reserved for selected cases and is not indicated for the majority of recurrent inguinal hernias.39 When an open pre-peritoneal approach is used with pre-peritoneal mesh implantation, the re-recurrence rate ranges between 0.5% and 25% after an observation period of up to 10 years, suggesting that this technique may require a degree of surgical experience for success.40,41 Divergent results are also reported for the Stoppa technique, with re-recurrence rates varying between 1% and 12%.42,43 The most likely explanation for this wide variation is that the size and type of recurrence probably varied between the reporting centres, and there is variation in the length and the quality of the follow-up.
Laparoscopic repair of recurrent inguinal hernias
The 2004 NICE25 report acknowledges that after a previous open repair, laparoscopic repair is the preferred technique. The advantages of the laparoscopic approach include: elimination of one of the commonest causes of recurrence, the missed hernia; allowing the surgeon to identify those patients with complex hernias; and covering the entire myopectineal orifice, buttressing the intrinsic collagen deficit, thereby overcoming one of the causes of late recurrence. The complication rate is low, and the majority of such repairs are as easy as primary laparoscopic repair. The data from the Swedish Hernia Registry would support the benefit of a pre-peritoneal repair (open or laparoscopic) for recurrent inguinal hernia following a previous open non-peritoneal repair.44 The type of surgery following recurrence after a previous laparoscopic repair is less well defined, and is more governed by surgeon preference and expertise. It is the author's opinion that an open mesh repair is the best option following a failed TAPP repair, and a TAPP repair for a failed TEP repair. The TAPP approach allows assessment as to why the TEP repair failed, and maintains the speedier recovery of the laparoscopic approach over open repair. However, the significant adhesions following a TAPP make a redo TAPP much more difficult, but still possible in experienced hands.
The Asymptomatic Hernia
Traditional teaching used to suggest that once an inguinal hernia was detected, it merited repair to prevent hernia-related complications unless the patient was not fit for such surgery. However, increasing awareness of complications following hernia repair, particularly chronic pain, has questioned this approach. Two randomised trials have reported similar results but come to different conclusions.45,46 In essence, chronic pain on follow-up is similar between the operation group and the watchful waiting group. However, significant numbers in the watchful waiting group crossed over to the surgery arm because of increasing symptoms, but it is likely that such patients would tolerate complications of surgery better than if they were asymptomatic at the time of the surgery. Also, the risk of incarceration or strangulation is much lower than previously thought. Thus, following informed consent, surgery or watchful waiting for an asymptomatic hernia is appropriate. The younger the patient, or less fit the patient on presentation, then perhaps the earlier surgery should be offered, with suitable informed consent of the risks, benefits and alternatives to the proposed surgery.
Repair of an asymptomatic hernia does not increase the incidence of chronic pain as compared to a wait and see policy. Either treatment option is acceptable with appropriate informed consent.45,46 The majority of wait and see patients will cross over to surgery with time as their hernia increases in size and/or becomes more symptomatic.
Femoral hernia represents the third commonest type of primary hernia. It accounts for approximately 20% of hernias in women and 5% in men, strangulation being the initial presentation in 40%.
The femoral canal occupies the most medial compartment of the femoral sheath, extending from the femoral ring above to the saphenous opening below. It contains fat, lymphatic vessels and the lymph node of Cloquet. It is closed above by the septum crurale, a condensation of extraperitoneal tissue pierced by lymphatic vessels, and below by the cribriform fascia. The femoral ring is bounded anteriorly by the inguinal ligament and posteriorly by the iliopectineal (Cooper) ligament, the pubic bone and the fascia over the pectineus muscle. Medially, the boundary is the edge of the lacunar ligament, while laterally it is separated from the femoral vein by a thin septum (Fig. 4.4).
Femoral hernias are considered to be acquired, possibly as a result of increased abdominal pressure on the background of disturbed collagen metabolism. A postulated mechanism is the insinuation of fat into the femoral ring secondary to raised intra-abdominal pressure. This bolus of fat drags along pelvic peritoneum to develop a peritoneal sac. Once the peritoneal sac has moved the short distance down the canal and out of the femoral orifice, the sac becomes apparent. The hernia not only becomes visible and palpable, but the contents of the sac become at risk of incarceration and strangulation. The incidence of femoral herniation increases with age, and a potential mechanism for this involves the muscle bulk adjacent to the distal femoral canal. Normally, the iliopsoas and pectineus muscle bundles encroach on the canal and thus act as a barrier to the development of a femoral hernia. With the natural atrophy of muscle tissue that occurs with senescence, the actual volume of muscle within the canal decreases, allowing positive intra-abdominal pressure to push the peritoneum into the canal. This would explain the high rate of femoral hernia among elderly women as well as men. In women of all ages, the muscle mass is not as great as in men. Consequently, women are predisposed to femoral hernias with any condition that increases intra-abdominal pressure, such as pregnancy or obesity.
The treatment of femoral hernia is surgical repair due to the invariable presence of incarceration and the associated risk of strangulation. Several operative approaches have been described: the low approach (Lockwood), the high approach (McEvedy) and the inguinal approach (Lothiessen). To these can now be added the laparoscopic approach.
The Low Approach (Lockwood): The low approach is based on a groin-crease incision and dissection of the femoral hernia sac below the inguinal ligament. The anatomical layers covering the sac should be peeled away and the sac opened to inspect its contents. Once empty, the neck of the sac is pulled down, ligated as high as possible and redundant sac excised. The neck then retracts through the femoral canal and the canal is closed with a plug or cylinder of polypropylene mesh, anchored to the inguinal ligament and iliopectineal ligament with non-absorbable sutures. Suturing of the iliopectineal ligament to the inguinal ligament may result in tension due to the rigidity of these structures and may predispose to recurrence.
Transinguinal Approach (Lothiessen): Techniques of femoral repair that open the posterior inguinal wall for exposure and repair (the inguinal approaches of Lothiessen, Bassini, Shouldice, McVay–Cooper, Halsted and Andrews) should rarely be used. This technique usually involves ligation and division of the inferior epigastric vessels at the medial border of the internal inguinal ring followed by incision of the transversalis fascia to expose the extraperitoneal space and the femoral hernia sac. This is reduced and the defect closed by either suture (as in the original description) or, increasingly, mesh. However, the need to incise the natural fascial barrier in Hasselbach's triangle for exposure results in this technique being inferior to either the low or high approach, both of which leave the inguinal floor intact.
High Approach (McEvedy): The high approach was classically based on a vertical incision made over the femoral canal and continued upwards above the inguinal ligament. This has now been replaced with a transverse ‘unilateral’ Pfannenstiel incision, which can be extended to form a complete Pfannenstiel incision if a formal laparotomy is required. The dissection is continued through the subcutaneous tissue to the anterior rectus sheath. This can either be divided transversely or longitudinally, following which transversalis fascia is incised, the rectus muscle retracted medially and the pre-peritoneal space entered. The femoral hernia sac is identified medial to the iliac vessels and reduced by traction. If the hernia is incarcerated, the sac may be released by incising the insertion of the iliopubic tract into Cooper's ligament at the medial margin of the femoral ring. The sac is then opened, the contents dealt with appropriately and the sac ligated at its neck. The hernioplasty may then be completed by either suturing the iliopubic tract to the posterior margin of Cooper's ligament or by insertion of a prosthetic mesh, either as a sheet covering the whole of the myopectineal opening or as a mesh plug. The wound is closed in layers. This technique is particularly useful in the presence of strangulated femoral hernias as it is easy to convert to laparotomy for bowel resection.
Laparoscopic Approach: The laparoscopic approach is the same as for inguinal hernias and may employ the TAPP or TEP technique. The femoral ring is easily seen during either of these approaches and, indeed, visualisation of the whole of the myopectineal opening is frequently quoted as one of the advantages of laparoscopic herniorrhaphy. Small series of laparoscopic femoral hernia surgery have been reported with excellent results on short-term follow-up.47,48
Incisional hernias are unique in that they are the only hernia to be considered iatrogenic. The cause of wound complications after laparotomy is multifactorial, conditioned by local and systemic factors and by preoperative, perioperative and postoperative factors. Several factors including advanced age, pulmonary disease, morbid obesity, malignancy and intra-abdominal infection are associated with impaired wound healing and predispose patients to serious wound complications such as wound dehiscence, wound infection and incisional herniation. It is always easy to blame the patient for complications! But surgeon or technical factors influencing wound complications include surgical technique and suture material choices.
What is the best way to close the abdominal wall? It is amazing that today we still don't know for sure. A recent review49 proposed mass closure (as compared to layered closure), continuous (as compared to interrupted sutures) absorbable monofilament (as compared to non-absorbable monofilament and absorbable multifilament) with a suture length to wound length ratio of 4:1. However, studies continue to challenge such doctrine. A recent randomised controlled trial (RCT)50 comparing polypropylene to polydioxanone demonstrated no significant difference, and the 4-year incisional hernia rate was 23.7% and 30.2 %, respectively. Another recent RCT51 demonstrated no significant difference between interrupted and continuous sutures. Controversy over the 4:1 ratio also exists. This ratio can be achieved by big bites far apart or small bites close together. A recent RCT52 reported a 50% reduction in wound infection and a 67% reduction in incisional hernia rates in the 2–0 polydioxanone 20-mm-needle small bite arm compared to more conventional closure techniques. Using such a suture technique, suture to wound length ratios greater than 4:1 were not associated with increasing wound complications.53 Further trials are in progress to evaluate this and other techniques in wound closure to minimise the risks of the burst abdomen (sometimes called an acute hernia or deep wound dehiscence), wound infection and incisional hernia. Indeed, incisional hernia is the commonest complication of a laparotomy. The development of an incisional hernia is inevitable if there is separation of the fascia by 12 mm at 12 weeks, so it is not difficult to see that the events that lead to an incisional hernia are determined early in the healing phase, and technical issues are likely to have a significant part to play.
Closure of a laparotomy wound to minimise incisional hernia formation includes:49
The diagnosis of an incisional hernia is usually easy except in the very obsese. However, computed tomography (CT) scanning is helpful to identify the size of the defect and the state of the adominal wall muscles (Fig. 4.8).
FIGURE 4.8 CT scan of a large incisional hernia demonstrating loss of domain. The gap between the medial ends of the left and right recti muscles on this slice is 25 cm.
The large number of surgical procedures described in the literature to repair incisional hernias illustrates that no single technique has stood out as being effective. While 50% of incisional hernias occur within 1 year after the primary operation, 10–18% are diagnosed more than 5 years later. Any study reporting re-recurrence rates following incisional hernia repair should therefore ideally have at least 5 years of follow-up data for analysis. Unfortunately, prospective randomised trials comparing different types of incisional hernia repair are lacking and the majority of studies are retrospective.
As a consequence of the disappointing data on mesh-free repair of incisional hernias, including the Mayo (‘vest-over-pants’) procedure, meshes were introduced to strengthen the abdominal wall repair. Several different techniques were developed: inlay, onlay and sublay (Fig. 4.9). Mesh implantation as an inlay does not achieve any strengthening of the abdominal wall and is essentially a suture repair at the muscle/fascia mesh interface. It has the highest recurrence rate of the three techniques. The results of randomised trials comparing mesh to suture repair demonstrate a clear advantage for mesh repair, even for small hernias.54,55 However, incisional hernia should be considered an incurable disease, mesh just increasing the time from repair to recurrence.56 Although suture repair is now rarely indicated, it might still have a role in young women who wish repair of an incisional hernia but are also contemplating further pregnancy.
FIGURE 4.9 Cross-sectional appearance of mesh position in incisional hernia repair. Reproduced from Schumpelick V, Klinge V. Immediate follow-up results of sublay polypropylene repair in primary or recurrent incisional hernias. In: Schumpelick V, Kingsnorth AN (eds) Incisional hernia. Berlin:Springer-Verlag 1999; pp312-26. With kind permission of Springer Science + Business Media.
Mesh repair of incisional hernia reduces the recurrence rate, even for small hernias.54,55
The onlay technique remains the commonest technique in the West, largely because it is relatively easy to perform. The technique is dependent on closure of the anterior abdominal wall and adequate fixation of the mesh to the fascia and a minimum overlap of 5–8 cm is recommended. If the connection between the mesh and the fascia is lost, a buttonhole hernia develops at the edge of the mesh. Good results can be reported with attention to detail, namely wide overlap of the mesh, and obliteration of large skin flaps with fibrin glue.57 However, for many surgeons the relatively high rate of hernia recurrence, seroma formation and mesh infection make this operation a poor option for the patient.
The sublay technique is the procedure favoured by the author. A mesh in the sublay position is not only sutured into position but is also held in place by the intra-abdominal pressure. Mesh in this position is therefore able to strengthen the abdominal wall both by mechanical sealing and by the induction of strong scar tissue. Several authors have compared the recurrence rate in a single institution where all three techniques have been used.58,59 Both these studies clearly demonstrate the superior results achieved by the sublay technique.
Open Sublay Repair: The sublay operation begins by excising the old scar and performing a laparotomy. Adhesions tend to be maximal at the neck of the sac, so entering the abdominal cavity through the hernia sac is usually straightforward. It is helpful to mobilise adhesions off the underside of the anterior abdominal wall. It is not the author's routine practice to mobilise all the bowel adhesions unless there is a good history of recurrent episodes of obstruction. The sublay space is then developed, which is the space anterior to the posterior rectus sheath, although this becomes pre-peritoneal below the semi-arcuate line. Care should be taken to mobilise the inferior epigastric vessels up with the belly of the rectus muscle to minimise bleeding. It is also important to preserve as many of the intercostal nerves as possible to minimise muscle denervation (Fig. 4.10). The pre-peritoneal space can be developed behind the pelvis, akin to a TEP repair, especially if the hernia arises in a Pfannensteil incision. Superiorly, the sublay space can be developed behind the xiphisternum if necessary. The posterior rectus sheath is divided on either side close to the linea alba to expose the area known as the fatty triangle (Fig. 4.11). The posterior rectus sheath is approximated with an absorbable suture. The mesh is cut to size, aiming to have at least a 6-cm overlap in all directions. This mesh is sutured to the posterior rectus sheath with interrupted absorbable sutures, avoiding any obvious nerves. These sutures are purely to hold the mesh flat until it is encased in fibrous tissue. A suction drain is often left anterior to the mesh. Any further redundant skin and hernial sac is excised and the anterior rectus sheath closed with an absorbable suture, as is the skin, minimising any subcutaneous dead space. The cross-sectional appearance is illustrated in Fig. 4.12. If an abdominoplasty is performed at the same time, then further drains are placed to the subcutaneous space.
FIGURE 4.10 Fresh cadaveric dissection of the retromuscular space for sublay incisional hernia. Used with permission of Dr J Conze, Aachen, Germany.
FIGURE 4.11 Fresh cadaveric dissection demonstrating the fatty triangle by division of the posterior rectus sheath as it attaches to the linea alba. This allows development of the sublay space behind the xiphisternum. Used with permission of Dr J Conze, Aachen, Germany.
FIGURE 4.12 (a) Cross-sectional appearance of peritoneum closure showing the sublay position of the mesh, which is fixed to the posterior sheath of the rectus muscle with an interrupted absorbable suture. (b) The anterior and posterior rectus sheath is closed continuously.
The open sublay technique for incisional hernia repair has a lower recurrence rate and wound complication rate compared to onlay or inlay repair techniques.58,59Randomised trials comparing the three mesh position techniques are lacking.
Laparoscopic Repair: The laparoscopic (intraperitoneal) approach has also been applied to incisional hernias. The laparoscopic approach has the advantages of shorter hospital stay, lower analgesic requirements, fewer wound complications and an earlier return to normal activities over open surgery. However, while the complication rate is lower overall when compared to surgery, there is concern that when complications do arise with the laparoscopic approach, they are more likely to be life threatening or require further surgery to deal with compared to open surgery.60 Furthermore, the cosmetic result for larger hernias may not be as good as there is no abdominoplasty component to the laparoscopic approach. Remember, the majority of patients wish surgery for their incisional hernia because of the cosmetic deformity rather than symptoms related to the hernia. The author reserves the laparoscopic approach for smaller incisional hernias, with a hernial neck size less than 10 cm and when cosmesis is not an issue. Two current controversies exist in the technique, related to (i) the method of fixation of the mesh and (ii) whether the hernia defect should be closed or not. The method of mesh fixation divides surgeons between those who believe transfascial sutures to be essential to prevent hernia recurrence and those who believe such sutures cause chronic pain post-surgery and their use should be avoided. The author prefers a double-crown tack technique (two rings of tacks around the hernia defect), although there is a lack of quality studies to make this an evidence-based decision. The recent introduction of absorbable tacks may reduce the risk of chronic pain and bowel adhesion to the tacks. Centring the mesh over the hernial defect is important to minimise hernia recurrence. The mesh can be centred with a central stitch,61although two or four corner sutures are probably more accurate.
What about closure of the defect? Bridging of the defect is recognised to be a problem at open surgery, so why bridge with laparoscopic surgery? It is clear that once adhesions to the abdominal wall are taken down, inserting a mesh and tacking it in place are usually quick and easy. Closing the defect is thus not attractive to the majority of laparoscopic surgeons, introducing tension and perhaps increasing postoperative pain. However, many groups are talking about pseudo-recurrence62 – the redevelopment of a bulge at the hernia site several years after laparoscopic repair as the mesh slides into the hernia sac. Whether closing (either completely or partially) will reduce recurrence and pseudo-recurrence is still unknown but would seem likely.
One of the main long-term risks of the laparoscopic repair of incisional hernias is the placement of the mesh in direct contact with the intra-abdominal structures. As mentioned earlier, the use of meshes that have one side coated with a relatively non-adhesive material will help reduce (but not abolish) adhesion formation to the mesh. The other main risk is infection of the mesh, which is nearly always due to contamination from a bowel injury. Care should be taken with any adhesiolysis to minimise bowel injury with thermal sources such as diathermy and ultracision dissection kept to a minimum. The current consensus is that if the colon is injured, then it should be repaired, laparoscopically or open, according to the skills of the surgeon and no mesh inserted at this time. The patient can return in a number of months for a further attempt at repair. If the small bowel is injured with minimal contamination, then laparoscopic repair, washout and mesh insertion is acceptable. If there is significant small-bowel injury and risk of failure of the bowel repair, then no mesh should be inserted. The patient should be observed in hospital and if they remain well 4–5 days later, then it is appropriate to re-laparoscope the patient and if no continuing contamination/infection is observed, the laparoscopic mesh repair is completed. The use of antibiotic-impregnated mesh may allow a change to this policy with placement of such a mesh at the same time as bowel injury and repair.63
Emergency hernia surgery
Much of what has been mentioned above is applicable to hernia repair in the emergency situation. However, there are a few dilemmas that occur more frequently in the emergency setting. Patients who present as an emergency but have no bowel compromise can be treated as per elective hernia surgery. When bowel is compromised, especially when there has been significant contamination, current opinion is that synthetic mesh should not be used. However, there is little in the way of evidence apart from anecdote to support such a view and this view has been challenged.64 The case for biological mesh in such scenarios is also lacking in evidence.65 For those who support the laparoscopic approach, it is not unreasonable to offer this in the emergency setting and laparoscope the patient with an irreducible inguinal hernia. If the bowel can be reduced and is viable, then convert the operation to a TEP and place mesh as usual. If the bowel is compromised, then resect the bowel through a small incision and return 6 weeks later for a TEP. In the emergency incisional/ventral hernia setting, if the hernia is large, then proceed directly to open sublay mesh repair. If the hernia is smaller, then laparoscopy and intra-abdominal mesh are appropriate if there is no bowel compromise. If there is bowel ischaemia, then convert to the open sublay repair. The use of mesh in the sublay space in the emergency setting should not be associated with an increase in mesh infection as it lies external to the peritoneal cavity, but clearly each case will need to be assessed individually.
Emergency hernia surgery remains a high-risk surgical procedure, with the main risk factor for postoperative mortality being infarcted bowel.66,67 Such operations should not be left to junior members of the surgical and anaesthetic teams. Appropriate resuscitation, followed by timely and appropriate surgery, may save lives. Occasionally, the techniques of damage limitation surgery (see Chapter 13) may be appropriate.
Bowel infarction is the main risk factor for mortality in emergency hernia surgery.66,67
This is a hernia with an increasing incidence associated with the increase in laparoscopic surgery. Insertion of larger ports through the midline as opposed to more laterally appears to be a significant risk factor. This is especially true in the presence of a divarification of the recti or an unrecognised umbilical hernia. There is little evidence to support closure of the fascia except when a cut-down is performed for the first port. The use of dilating rather than cutting trocar tips may reduce the incidence of port-site hernia formation.
Antibiotic prophylaxis in hernia surgery
In general, elective hernia surgery to the groin and ventral regions does not require antibiotic prophylaxis.68,69 However, as the risk of bowel injury is always present in incisional hernia surgery, it would be reasonable to give routine antibiotic prophylaxis for such surgery. Patients at increased risk of infection, including the immunocompromised, skin conditions with higher bacterial carriage such as psoriasis and in the emergency setting, all merit antibiotic prophylaxis.
All theatres have bacteria (called colony-forming units) in the circulating theatre air. It therefore makes sense to open the mesh just before it is required during the operation. Changing to fresh gloves before the handling of the mesh, minimising mesh contact with the skin and inserting the mesh deep to the subcutaneous tissues may all help reduce the risk of mesh contamination. The author uses a gentamicin solution (240 mg gentamicin in 250 mL normal saline) to irrigate larger meshes following insertion, although there is no evidence-based medicine to support this manoeuvre. Methicillin-resistant Staphylococcus aureus (MRSA) bacteria have been found on mesh several years after insertion, so prophylaxis to MRSA is appropriate if a previous repair has been complicated by MRSA infection.
Antibiotic prophylaxis is unnecessary for uncomplicated elective hernia surgery to the groin and ventral regions.68,69
Prophylatic hernia surgery
The topic of prophylactic mesh insertion to minimise subsequent hernia formation in high-risk groups of patients remains controversial. One study reduced the incidence of incisional hernia following open gastric bypass surgery from 21% to 0% by the prophylactic insertion of a polypropylene mesh in the sublay position.70 Another study reduced the incidence of parastomal hernia following permanent end colostomy from 50% to 5% by the prophylactic insertion of a polypropylene mesh in the sublay position at 2 years' follow-up.71 At 5 years' the rates were 81% and 13%, respectively.72 Both studies have small patient numbers, but no increase in morbidity was noted in the prophylactic mesh group. It is likely that prophylactic mesh to minimise subsequent hernia formation will become more mainstream practice. This may be supported by preoperative collagen type I/III ratio typing to perhaps select patients more at risk. This concept of collagen disease is important, and introduces the notion that hernia repair of any type will fail if the patient lives long enough. It is true that some surgeons' repairs last longer than others, so technical factors remain important, and mesh repairs at any time point are more likely to be intact compared to a suture repair.56 (Re-operation rates are a surrogate for recurrence rates, although re-operation will underestimate the true recurrence rate.) However, a hernia repair at present is a patch-up job, and will probably fail eventually (if the patient lives long enough). Nevertheless, randomised trials in patients at high risk of developing incisional hernia are ongoing.
Management of an infected mesh
In general, an infected mesh has to be removed or exposed to the surface. If the mesh is lying in a pool of pus with no adherence to the patient, then the only option is removal of the mesh. If the mesh is partly embedded in tissue, then if there is adequate drainage through an open wound, many infected meshes will slowly granulate over and remain sound. However, sometimes chronic sinuses will develop and the only option is excision of these along with as much of the visible mesh as possible. Not all patients who require mesh removal will develop a hernia recurrence, although the majority probably will at some stage in the future.73 It is the author's opinion that it is best to remove as much of the mesh foreign body as possible, control the sepsis and return at a later date for further repair. The use of biological mesh in a contaminated field is rarely indicated. The use of vacuum-assisted dressing to control the fluid exudates from the wound may aid wound care in such patients.