7.11 Herniae

Introduction

A hernia is defined as the protrusion of a viscus or part of a viscus into an abnormal location. The most common herniae occurring in children are inguinal and umbilical – femoral herniae are rare. A variety of descriptive terms is applied to herniae in these locations, often incorrectly. This may lead to diagnostic confusion and inappropriate delays in referral.

Herniae are usually classified based on two characteristics: anatomical location and whether or not the hernia is reducible. An irreducible hernia may result in ischaemia of either the contents of the hernia or adjacent structures. Treatment of an irreducible hernia is thus a surgical emergency. The use of the terms incarceration (irreducible) and strangulation (arrest of circulation) should be avoided, as all irreducible herniae may be associated with ischaemia.

Types of herniae

Inguinal

The incidence of inguinal herniae in children has been reported to be between 0.8% and 4.4%,¹ rising to 18.9% to 30% of preterm infants.^2,³ Inguinal herniae are six times more common in boys and are more common in twins.^1,⁴ Around 1 in 10 inguinal hernias are non-reducible at presentation, although a careful history from the parents will often elucidate earlier signs and symptoms. In this group, over two-thirds are under 1 year of age.

In children, inguinal herniae are almost always indirect.⁵ The hernia exits the peritoneal cavity via the internal inguinal ring to enter the inguinal canal, leaving the canal via the external inguinal ring. The sac is intimately related to the contents of the spermatic cord. It is compression of the testicular vessels by hernial contents that may render the testis ischaemic. In contrast, in females the risk of ischaemia to the ovary and adnexae usually occurs as a result of torsion of these structures within the hernial sac.

Rarely, direct inguinal herniae may occur, with some series reporting an incidence of up to 5%.⁶ Typically, these children have either had previous inguinal surgery, a connective tissue disorder or were delivered at less than 30 weeks’ gestation. The clinical management and surgical approach remains similar to indirect inguinal herniae.

Inguinal herniae usually present as a swelling in the inguinal region first noticed by the carer when changing or bathing the child, especially if crying or straining.⁷ The swelling may extend into the scrotum in boys or the labia majora in girls. Persistent tachycardia, overlying erythema and marked tenderness suggest an irreducible hernia complicated by ischaemia.⁸ Occasionally, an irreducible hernia may present with vomiting and abdominal distension as a result of intestinal obstruction.

A hernia can be differentiated from a hydrocele as the latter transilluminates and does not usually extend into the inguinal region. In neonates, these differences may be less obvious and a hernia may appear to transilluminate. Encysted hydroceles of the cord and, rarely, testicular torsion may also cause diagnostic confusion. Where there is any doubt regarding the diagnosis, a paediatric surgeon should be consulted.

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