Gastroenterology and Hepatology Board Review: Pearls of Wisdom, Third Edition
Section I GASTROENTEROLOGY
CHAPTER 3. Abdominal Cavity: Congenital Abnormalities, Abscesses, and Fistulae
James A. Madura, II, MD, FACS
What are the two main anatomic features of intestinal malrotation that lead to clinical symptoms?
1. Ladd bands, which cross the duodenum, can cause duodenal obstruction.
2. Narrow mesenteric base/pedicle, which results in excessive small bowel mobility, can lead to volvulus and bowel ischemia.
True/False: Intestinal rotational anomalies are always associated with other congenital gut anomalies.
False. While intestinal malrotation and nonrotation are often associated with other gut anomalies, particularly those in which the intestines are located outside the peritoneal cavity (eg, congenital diaphragmatic hernia or abdominal wall defects), they can also occur in children and adults who have no associated anomalies.
True/False: Intestinal nonrotation is not as dangerous as malrotation because the base of the mesentery is usually wider than in malrotation and the risk of volvulus is less.
True/False: Intestinal malrotation is a disorder of infancy and does not occur in adults.
False. Although intestinal malrotation has been considered primarily a disease of infancy with infrequent occurrence beyond the first year of life, more recent reports suggest it is not uncommonly first detected in adults.
True/False: Intestinal malrotation in adults usually presents as an abdominal catastrophe (eg, volvulus with bowel ischemia).
False. Intestinal malrotation in adults is often detected incidentally as part of an evaluation of chronic nonspecific gastrointestinal symptoms. Volvulus and other complications of malrotation appear to occur less commonly in adults.
True/False: The cornerstone of the surgical treatment of intestinal malrotation is to restore the normal configuration of the bowel.
False. The restoration of normal bowel configuration is not possible. The objective of the Ladd procedure is to minimize the risk of future volvulus by widening the base of the mesentery and placing the bowel in a position of nonrotation (ie, small bowel on the right and colon on the left). Division of Ladd bands, if present, and an appendectomy is also done.
True/False: Adults with asymptomatic or incidentally discovered malrotation should undergo the Ladd procedure.
This remains controversial with proponents on both sides and so there is no clear right or wrong answer. Because it is not clear that the risk of volvulus decreases with age and it is difficult to determine with imaging studies whether a patient with a rotational anomaly has a narrow-based mesentery, many surgeons recommend surgery regardless of the patient’s age or the presence of symptoms characteristic of malrotation. One approach that has been advocated is the use of diagnostic laparoscopy to assess the mobility of the colon and the width of the mesentery. In patients with narrow mesenteric attachment and potential colonic mobility, definitive laparoscopic correction can then be undertaken.
How and where is particulate material in the peritoneal cavity normally cleared from the cavity?
Through modified lymphatics located along the diaphragm undersurface, stomas of which open when the diaphragm relaxes creating negative intra-abdominal pressure. Diaphragmatic muscle contractions then force lymph cephalad, aided by one-way valves.
The presence of rebound or percussive tenderness and guarding helps to diagnose peritonitis in what way?
They indicate extension to and irritation of the abdominal wall peritoneal surface, whereas localized inflammatory processes between visceral surfaces produce nonspecific, dull aching pain that may be difficult to localize.
What is the desired timing for initiating antibiotics to treat peritoneal contamination?
The estimated “grace period” is 4 to 6 hours after contamination, the earlier the better. Antibiotics should always be started before percutaneous or surgical intervention.
Clinically significant Candida peritonitis, usually responsive to low-dose amphotericin B or fluconazole, is most likely to be found in what situations?
In patients on long-term antibiotics, after gastric perforations in acid suppressed patients and in immunocompromised individuals.
True/False: The process of abscess formation and maturation is deterrent but not cidal to contained bacteria. True. While abscess formation and maturation initially retards bacterial escape and septicemia and decreases bacterial access to oxygen and glucose, it also creates a barrier to penetrating phagocytes and systemic antibiotics. Therefore, bacteria can persist as vegetative forms and can rejuvenate in a changed environment; ergo, the surgical principle that abscesses must be drained.
What are the most common aerobic and anaerobic organisms recovered from intra-abdominal abscesses?
Aerobic: Eschericia coli
Anaerobic: Bacteroides fragilis
Although the overall incidence of intra-abdominal abscess has progressively declined, what is the most common cause?
While formerly perforated appendicitis, colonic diverticulitis is now the most common cause as a result of more rapid diagnosis and treatment of appendicitis.
When searching for an intra-abdominal abscess, a high-resolution CT scan is the procedure of choice with three limitations. Name the limitations.
1. Interloop abscesses.
2. Inability to differentiate sterile from contaminated fluid collections.
3. The post abdominal surgery patient.
Percutaneous drainage of abscesses after CT scan identification should be avoided in what situations?
• Noninfected peripancreatic phlegmon.
• Infected organized hematomas.
• Abscess with enteric fistulae.
• Fungal infections.
• Abscess within necrotic tumors.
How often are abdominal x-ray findings of pneumoperitoneum in an unoperated patient associated with a perforated hollow viscus?
90%. These cases require urgent surgical intervention.
Aside from iatrogenic causes of nonsurgical pneumoperitoneum, the second most common source of gas/air in the abdominal cavity is from where?
Above the diaphragm. Ruptured alveoli can lead to pneumomediastinum which can: 1) rupture into the pleural space and then into the abdomen directly through the diaphragmatic hiatus or fenestrations, or 2) dissect into the retroperitoneum and then rupture through the mesentery.
Name three other causes of noniatrogenic, spontaneous pneumoperitoneum.
1. Introduction of air through the female genital tract during sexual activity.
2. Pneumatosis cystoides intestinalis.
3. Cocaine use.
True/False: In patients with significant abdominal distension who develop oliguria unresponsive to hemodynamic changes or corrections, increased intra-abdominal pressure (IAP or “compartment syndrome”) should be considered.
True. Following the diagnosis of IAP (intra-abdominal pressure above 20 mmHg) measured with a bladder catheter and manometer, appropriate efforts, including surgical exploration, directed at intra-abdominal decompression should be followed with diuresis expected afterward.
An adolescent of Iranian or Jordanian ancestry develops episodic, nonradiating, diffuse abdominal pain with associated fever and without any postepisode sequelae. What inherited disorder may he have?
Familial Mediterranean Fever.
A 25-year-old woman describes the acute onset of severe localized right lower quadrant pain. A CT scan is performed revealing epiploic appendagitis. What is the most appropriate treatment?
Pain is addressed with analgesia and should resolve in a week’s time. No surgical or other medical treatment is required. Epiploic appendagitis is a self-limiting condition resulting from torsion or venous thrombosis of a fatty projection (epiploic appendage) from usually the ascending colon.
Aerophagia may cause sudden localized or diffuse abdominal distention with normal bowel sounds and localized tympany and pain. Most often, the air collects in what two places?
Stomach and splenic flexure of the colon.
Although the specific risk of postoperative abdominal adhesive complications may vary according to the acute need and location of the initial surgical procedure, what is the approximate overall risk of hospital readmission later for these complications?
Studied over a 10-year follow-up interval, 4% of 30,000 initial procedures and 5.5% of hospital readmissions were directly attributable to postoperative adhesions.
A rectal shelf of Blumer is often associated with metastatic gastric or breast cancer. How is this distinguished from a rectal stricture?
The Blumer shelf is an extrarectal mass indenting the anterior wall of the rectum and is distinguished from a stricture by the fact that: 1) it does not encircle the circumference and 2) often the mucosa can be made to move over the shelf.
Carnett’s test is a physical examination means of differentiating an abdominal wall mass from an intraabdominal mass (and abdominal wall pain from intra-abdominal pain). How is this test performed?
The supine patient is asked to extend his legs and lift his/her feet up from the bed or table, thereby tensing the abdominal musculature. Alternatively, the patient can raise his/her head. An intraperitoneal mass will nearly disappear when the abdominal muscles tighten, whereas an abdominal wall mass will persist. Likewise, pain from an intra-abdominal source will usually lessen, whereas abdominal wall pain will not.
Abdominal wall crepitance surrounding an early postoperative incision but without wound discharge, pain, odor, or skin discoloration has what significance?
It is innocuous. Termed “pseudo-gas gangrene,” it occurs because air is entrapped in the subcutaneous tissue. It will soon be absorbed. This is especially common after laparoscopic procedures. If there is any doubt, prompt surgical intervention in the form of wound exploration should be undertaken to rule out early clostridial soft tissue infection.
Acute development of a tender lump in the right lower quadrant after spasmodic coughing, about half-way between the umbilicus and pubic tubercle, may likely be due to what?
Rectus muscle rupture or torn inferior epigastric artery. This may be differentiated from a strangulated Spigellian hernia by the absence of vomiting. Patients that are pregnant or on anticoagulant therapy are at increased risk for this problem.
What four structures may remain patent rather than obliterate in the umbilicus at birth?
1. Umbilical vein.
2. Omphalo-mesenteric duct (fecal).
3. Hypogastric arteries.
4. Bladder-urachal fistula (urine).
What is a likely cause of a sudden appearance of feculent discharge from the umbilicus in a middle-aged, unoperated patient?
Colonic diverticulitis or colon carcinoma.
Acute mesenteric lymphadenitis is as common as acute appendicitis and can mimic this disease in children. After what age does the incidence drop and become exceedingly unlikely?
Fifteen years of age.
Acute extra-abdominal conditions that are common and may mimic acute inflammatory intra-abdominal disease in adults number at least three. Name them.
1. Coronary occlusion/myocardial infarction.
2. Diaphragmatic pleurisy.
3. Herpes zoster.
A psychogenic disease, usually occurring in females, in which acute abdominal symptoms are out of proportion to physical findings and in which there are often several surgical scars on the abdomen is suggestive of what diagnosis?
What type of bowel fistulae frequently spontaneously close if surrounding active bacterial peritonitis is cleared?
Lateral bowel fistulae, which permit normal progression of some intestinal contents beyond the fistula through normal bowel.
If a colonic fistula is present, whether cutaneous or internal, what is the problem with treatment by proximal loop colostomy or cecostomy?
Neither procedure is totally diverting and thereby may cause persistent contamination.
The six major physical deterrents to spontaneous closure of an enterocutaneous fistula are
Remember the mnemonic FRIEND:
1. Foreign body
3. Inflammation/Infection/Inflammatory bowel disease (Crohn’s)
4. Epithelialization (gastrointestinal mucosa has fused with the skin)
6. Distal obstruction
The two potential benefits of parenteral nutritional support for bowel fistula closure are
1. Increased proportion close without surgical intervention.
2. Reduced average time for closure.
True/False: All enterocutaneous fistula treatment is aided by the use of somatostatin or octreotide. What are theoretical reasons for use of these agents?
False. Theoretical reasons for use include: 1) more rapid closure interval of high output fistulae by reducing the volume of pancreatic enzyme secretion, and 2) reduced duration of parenteral nutrition and its inherent morbidity because of more rapid closure rate. The ultimate closure of low volume fistulae is not enhanced by use of these peptides.
A defect in what lining or layer through which any abdominal wall hernia—be it umbilical, hiatal, inguinal, or incisional—must extrude is called?
The “endoabdominal fascia.” This is a continuous lining of the abdominal cavity that is given other names when it lies over various muscles, such as transversalis (muscle) fascia, psoas (muscle) fascia, and so on.
How does gastroschisis in newborns differ from omphalocele?
• Gastroschisis is a defect of the abdominal wall lateral to the umbilicus that results when the abdominal wall has failed to close, whereas omphalocele is a defect in closure of the umbilical ring.
• No sac is found over the protruded intestines in gastroschisis, whereas an amniotic sac usually lies over the intestines in omphalocele.
• Omphalocele is associated with other birth defects, gastroschisis is not.
• Bowel loss is more likely in gastroschisis due to amniotic fluid peritonitis and bowel torsion/infarction.
Persons with cystic remnants or fibrous bands at the umbilical end of the omphalomesenteric duct are at risk for what problems?
Acute volvulus and intestinal obstruction. Occasionally, an acute abdomen due to cyst infection may occur.
What is the persistence of the intestinal end of the omphalomesenteric duct called?
Meckel’s diverticulum. This is a true intestinal diverticulum with all intestinal wall layers represented.
Congenital abdominal hernias that are caused by abnormal rotation of the intestine and create obstructive symptoms in adults (usually) have what two anatomic descriptions.
1. “Right mesocolic” with entrapment of proximal small bowel in mesentery under the right colon.
2. “Left mesocolic” with entrapment of rotated small bowel under the left/sigmoid colon.
One month after an uncomplicated aortic aneurysm repair, a 65-year-old man presents with a painless, gradually distended abdomen. Shifting dullness and a fluid wave are noted on examination. Paracentesis returns a milky white fluid rich in triglycerides. What is the diagnosis and initial treatment?
Chylous ascites from surgically disrupted lymphatics. Post surgical chylous ascites usually resolves with supportive therapy. Paracentesis is reserved for diagnosis and symptoms. A diet eliminating long chain triglycerides should be instituted. Octreotide (100 mcg subcutaneously three times per day) can be tried in refractory cases. Prolonged bowel rest with parenteral nutrition support should be considered for more refractory cases. Rarely, surgical ligation of the lymphatics is necessary.
• • • SUGGESTED READINGS • • •
Nehra D, Goldstein AM. Intestinal malrotation: varied clinical presentation from infancy through adulthood. Surgery. 2011;149(3): 386-393.
Schecter WP, Hirshberg A, Chang DS, et al. Enteric fistulas: principles of management. J Am Coll Surg. 2009;209(4):484-491.
Mazuski JE, Solomkin JS. Intra-abdominal infections. Surg Clin North Am. 2009;89(2):421-437.