Indirect Inguinal Hernia in an Infant

During the last few weeks of gestationor shortly after birth, the layersof the processus vaginalis normallyfuse together and obliterate the entranceto the inguinal canal in thevicinity of the internal inguinal ring.An indirect hernia results from a failureof fusion of the processus vaginalis;the bowel subsequently descendsthrough the inguinal canal.The incidence of indirect inguinalhernia in infants is 1% to 2%; the maleto female ratio is 9:1. The incidence ishigher in premature infants and thosewith connective tissue disorders, bladderexstrophy, and increased intra-abdominalpressure. There is a familialtendency for hernia formation. An indirectinguinal hernia is more commonon the right side, because of the laterdescent of the right testis and delayedobliteration of the processus vaginalis.Sixty percent of indirect inguinal herniasare on the right, 25% on the left,and 15% bilateral.Incarcerated indirect inguinalhernia is a common cause of intestinalobstruction in infants and youngchildren. The rate of incarceration issignificantly higher in premature infantsand those in the first year of lifethan in older children.An incarcerated hernia presentswith a painful irreducible mass in thegroin or scrotum (A). The overlyingskin may be erythematous. Vomiting,abdominal distention, and radiographicevidence of a bowel obstruction withgas in the groin or scrotum (B) confirmthe diagnosis. An incarceratedhernia may strangulate in a matter ofhours, resulting in infarction of the containedviscus and the ipsilateral gonad.Unless the child appears toxic orshows signs of peritonitis, a manualreduction of the incarcerated herniawith the child sedated should be attempted.Immediate surgery is indicatedif the incarcerated hernia is irreduciblemanually.