Inguinal hernias in children almost always result from a persistence of the patent processus vaginalis. Like hydroceles, peritoneal fluid can move into the scrotum, but unlike hydroceles, the processus vaginalis is large enough to allow bowel to herniate into the inguinal canal. The term 'indirect' refers to the fact that the bowel and peritoneal protrusion don't herniate directly through a weakness in the abdominal musculature. Rather, the bowel and peritoneal fluid move through a patent processus vaginalis into the scrotum. Direct inguinal hernias occur because of weakness in the floor of the inguinal canal.
Incidence: 3% in full term infants. Hernias are more common in premature males. The infant may have been born before the normal gestational age at which the patent processus closes (32-38 weeks).
Diagnosis: palpable mass along the inguinal canal. Placing a finger tip on the scrotum and extending the finger into the inguinal canal will demonstrate a patent tunnel and one may feel bowel within the canal.
Treatment: Inguinal hernias do not spontaneously resolve so surgery is required. If bowel becomes entrapped within the inguinal canal an incarcerated hernia can occur. This is a surgical emergency because the entrapped bowel can become ischemic.
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©David A. Hatch, M.D., 1996