Strange and Schafermeyer's Pediatric Emergency Medicine, Fourth Edition (Strange, Pediatric Emergency Medicine), 4th Ed.

CHAPTER 47. Inguinal Hernia

Jeffrey F. Linzer Sr.

HIGH-YIELD FACTS

• Most inguinal hernias are asymptomatic and are managed by referral to a pediatric surgeon for elective management.

• Incarcerated hernias are best reduced by the taxis method.

• Inability to reduce an inguinal hernia requires emergent referral to a surgeon.

Inguinal hernias are among the most common congenital conditions in children. They have a reported incidence of 0.8% to 4.4% in children1 and 3.5% to 5% in full-term newborns2 with a 10-fold increase in males versus females.3Premature infants of less than 36 weeks gestational age have a rate approaching 7%,4 with the highest rate seen in infants less than 28 weeks of gestational age or with a birth weight less than 1000 g.2 Ten percent of these may become incarcerated before 1 year of age,5 with the greatest risk occurring during the first 6 months of life.6

ANATOMY

Hernias in the groin can be divided in to three types: direct, indirect, and femoral. An indirect inguinal hernia occurs when abdominal contents pass through the internal ring and then traverse the inguinal canal into the scrotum. Congenital inguinal hernias, by far the most common, are indirect by definition7 due to a processus vaginalis that fails to fully close. Direct inguinal hernias are rare in children and occur when there is a weakness in the abdominal musculature allowing intestine to protrude into the inguinal canal. Femoral hernias pass into the femoral canal and not into the scrotum or labia.

There is an outpouching of the peritoneum into the inguinal canal by the processus vaginalis about the third month of gestation. In males, the testes descend into the scrotum during the seventh month of gestation, the left usually preceding the right. The processus vaginalis will remain partially patent in approximately 70% of term male infants in the first 2 weeks after birth but will be virtually obliterated by the third week, again the left before the right.8 This probably explains why a majority of inguinal hernias are found on the right side (60%) compared with 30% on the left and 10% bilaterally.9

The processus vaginalis does not become as deep in females since ovarian descent is restricted by the ovarian ligament. The extension of the processus vaginalis past the inguinal canal is referred to as the canal of Nuck in females. An indirect hernia can occur if it remains patent.

As opposed to a hernia where intestine enters the inguinal canal, a hydrocele may occur when the processus vaginalis narrows to the point that only fluid can pass (communicating). The hydrocele is noncommunicating when fluid is trapped after the processus closes.

SIGNS AND SYMPTOMS

In the first year of life, inguinal hernias most often present as a bulge in the groin, scrotum, or labia. The bulge may come and go and be exacerbated with crying, cough, or dyschezia. Although usually asymptomatic at times, the parent may report that the child is fussier when the bulge is present. Children may note a bulge along with a feeling of fullness in the affected area.

The hernia may be an incidental finding during a physical examination. The examiner may note a swelling in the groin, scrotum, or labia that has a smooth consistency and may withdraw through the inguinal ring when the child relaxes or with the application of gentile pressure. The “silk glove sign” involves palpating the spermatic cord in males or the processus vaginalis in females over the pubic tubercle. It is a highly accurate way (sensitivity of 91% and a specificity of 97.3%) of demonstrating a patent processus vaginalis.10 Examination in the male should include signs of a retractile testicle and in the female a protruding fallopian tube or ovary.

In differentiating between a hernia and a hydrocele, the hydrocele will transilluminate whereas a hernia will not. In addition, the examiner should be able to get their fingers above the hydrocele and not with a hernia since the hernia communicates with the abdominal cavity.11 Ultrasound can be helpful in the differentiating a hernia from a hydrocele.12,13

INCARCERATED HERNIAS

Incarceration of a hernia occurs when the abdominal contents become trapped within the patent process vaginalis and do not retract above the inguinal ring (Fig. 47-1). Although most often it is small bowel that becomes incarcerated, any abdominal contents are at risk. In females, this can include the ovary and fallopian tube. A hernia becomes strangulated when the blood supply becomes compromised. Initially, the flow to the lymphatics and veins is affected leading to engorgement of the trapped viscera and eventually reducing or stopping the arterial flow. This can ultimately lead to ischemia, gangrene, and perforation of the affected viscera. Blood flow to the testis can also be reduced leading to ischemic damage. Incarceration is most frequent in the first 6 months of life and is comparatively rare after 5 years of age.14

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FIGURE 47-1. The infant presented with inconsolable crying and a few episodes of vomiting. Inguinal hernia may be either unilateral or bilateral. This patient’s hernia (hernia sac contents) could not be reduced into the abdominal cavity and the patient required surgical repair.

With an incarcerated hernia, the child may develop fussiness, poor feeding, abdominal pain, or vomiting. A tender, nonfluctuant, palpable mass will be present in the inguinal area and may extend into the scrotum or labia. As strangulation ensues, bilious emesis from obstruction, blood in the stool, and fever along with signs of peritonitis and sepsis may occur. Strangulation can arise within 2 hours from the onset of incarceration.

TREATMENT

Most hernias will spontaneously retract or with the placement of the patient in Trendelenburg with mild pressure applied to the hernia sac. Incinerated hernias in the emergency department should be reduced, unless there are signs of obstruction or peritonitis. The manual reduction method called taxis (Fig. 47-2) has been shown to have a success rate of 75% to 85%.15 Prior to reduction, the child should be adequately sedated. In addition to providing analgesia for this painful procedure, it also decreases the child’s resistance that could raise intra-abdominal pressure making reduction more difficult or unsuccessful.

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FIGURE 47-2. Suggested method of reduction of an inguinal hernia. >A. Standing on the ipsilateral side of the child, or at the feet of an infant, place the left index and middle finger on the ipsilateral (left in this example) anterior superior iliac crest and sweep your fingers down along the inguinal canal, toward the ipsilateral scrotum. >B. Keep tension on the testicle, hernia mass, or scrotal skin with the left hand. C. Constant, gentle retraction on the scrotum helps align the long axis of the hernia with the axis of the inguinal canal. Next, apply pressure with the right index finger and thumb on either side of the hernia neck. D. This, along with traction on the scrotum, helps to keep open the external and internal rings, and prevents the hernia sac from overlapping or being caught on these potential barriers during reduction. E. Finally, with the left hand at the apex of the mass, and with constant pressure on the inguinal canal from your right index finger and thumb, walk your left fingers slowly up the groin toward the internal ring, keeping constant pressure on the bottom of the hernia contents. (Reproduced with permission from Kapur P, Caty MG, Glick PL. Pediatric hernias and hydroceles. Pediatr Clin North Am.1998;45(4):773–789.)

The taxis method has the practitioner gently applying downward traction along the hernia sac with one hand while applying slight pressure at the inguinal ring. The elongated hernia is then guided back through the ring into the abdominal cavity. Merely pressing on the hernia to force in back through the ring may cause the hernia sac to bulge and actually obstruct the path back preventing reduction.

All children with inguinal hernias, especially infants, should be referred to a pediatric surgeon. Those who require reduction of an incarcerated hernia should see the surgeon within 24 to 48 hours after discharge because of the risk of reoccurrence. Strangulated hernias are surgical emergencies requiring immediate referral to a pediatric surgeon.

REFERENCES

1. Bronsther B, Abrahams MW, Elbonim C. Inguinal hernia in children—a study of 1000 cases and a review of the literature. J Am Med Womens Assoc. 1972;27:5222–5535.

2. Aiken JJ, Oldham KT. Inguinal hernias. In: Kliegman RM, Stanton BF, Geme JW St III, Schor NF, Behrman RE, eds. Nelson’s Textbook of Pediatrics. 19th ed. Philadelphia, PA: Elsevier Saunders, 2011:1362.

3. Sherman V, Macho JR, Brunicardi FC. Inguinal hernias. In: Brunicardi FC, Andersen DK, Billiar TR, et al., eds. Schwartz’s Principles of Surgery. 9th (electronic version) ed. New York, NY: McGraw-Hill, 2010. http://www.accessmedicine.com/content.aspx?aID=5031117. Accessed January 7, 2013.

4. Skinner MA, Grosfeld JL. Inguinal and umbilical hernia repair in infants and children. Surg Clin North Am. 1993;73:439–449.

5. Weber TR, Tracy TFJ. Groin hernias and hydroceles. In: Ashcraft KW, Holdereds TM. Pediatric Surgery. 2nd ed. Philadelphia, PA: WB Saunders; 1993:562.

6. Singer J. Acute abdominal conditions that may require surgical intervention. In: Strange GR, Ahrens W, Lelyveld S, et al., eds. Pediatric Emergency Medicine: A Comprehensive Study Guide. New York: McGraw-Hill; 1996:311.

7. Hackam DJ, Grikscheit TC, Wang KS, Newman KD, Ford HR. Pediatric surgery. In: Brunicardi FC, Andersen DK, Billiar TR, et al., eds. Schwartz’s Principles of Surgery. 9th (electronic version) ed. New York, NY: McGraw-Hill; 2010, http://www.accesssurgery.com/content.aspx?aID=5029784. Accessed January 7, 2013.

8. Standring S. Development of the urogenital system. In: Borley NR, ed. Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 40th ed. Edinburgh: Churchill Livingston; 2008:1305.

9. Rowe MI, Copelson LW, Clatworthy HW. The patent processus vaginalis and the inguinal hernia. J Pediatr Surg. 1969;4:102–107.

10. Luo CC, Chao HC. Prevention of unnecessary contralateral exploration using the silk glove sign (SGS) in pediatric patients with unilateral inguinal hernia. Eur J Pediatr. 2007;166:667–669.

11. Malangoni MA, Rosen MJ. Hernias. In: Townsend CM Jr, Beauchamp RD, Evers BM, Mattox KL, eds. Hernias in Sabiston Textbook of Surgery. 19th ed. Philadelphia, PA: Elsevier WB Saunders; 2012:1114.

12. Chen KC, Chu CC, Chou TY, Wu CJ. Ultrasonography for inguinal hernias in boys. J Pediatr Surg. 1998;33:1784–1787.

13. Narci A, Korkmaz M, Albayrak R, et al. Preoperative sonography of nonreducible inguinal masses in girls. J Clin Ultrasound. 2008;36:409–412.

14. Kapur P, Caty MG, Glick PL. Pediatric hernias and hydroceles. Pediatr Clin North Am. 1998;45:773–789.

15. Harissis HV, Douitsis E, Fatouros M. Incarcerated hernia: to reduce or not to reduce? Hernia. 2009;13(3):263–266.