The testis descends into the scrotum in the 28th week in utero through a diverticulum of the peritoneum, the processus vaginalis. Failure of obliteration of the processus vaginalis leads to inguinal hernias, hydroceles and encysted hydroceles of the cord. An inguinal hernia is a peritoneal pouch that extends through the inguinal canal sometimes as far as the scrotum. Bowel can pass into it.
An inguinal hernia usually presents as an inguinal swelling that is often intermittent so may not be noticed until the baby cries or strains. All inguinal hernias require prompt surgical referral once diagnosed because small bowel can easily become trapped in the hernia compromising the bowel's blood supply and causing bowel obstruction (strangulation). Symptoms of strangulation include inability to squeeze the hernia back (irreducible), excessive crying and later vomiting, abdominal distension and constipation.
Inguinal hernias are more common in premature babies. They can occasionally occur in females (and are more common in preterm than term females).
A reducible inguinal hernia requires an early surgical consult and will usually be repaired on the next convenient surgical list.
An irreducible or strangulated hernia requires urgent surgical referral.
Premature infants should have their hernia repair prior to discharge. Post-operative apnoea is less common after 42 corrected weeks of gestation.
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Smart, J. (editor). Paediatric Handbook. 6th edition. Blackwell Science Pty Ltd. 2000.
Balfour-Lynn, I.M. and Valman, H.B.V. Practical Management of the Newborn. 5th edition. Blackwell Science Pty Ltd. 1993.