[Inguinal herniotomy in prematurely born infants]

Inguinal hernia is the most common surgical condition in childhood; more than half of the cases occur during infancy (1, 2). As the number of surviving premature infants continues to grow, the pediatric surgeon has become more involved in the management of these hernias (3, 4). Several issues are contentious, such as the optimal time for herniotomy after diagnosis (5), the role of contralateral exploration, and the proper management for incarcerated inguinal hernia (6). Based on our experience, we attempted to study the above points in the infant population and we also examined the role of ventilator therapy in the etiology of inguinal hernia.

We performed a retrospective review of records of all infants under 6 months of age who underwent a repair of inguinal hernia at the Clinic for Pediatric Surgery in Novi Sad between January 1994 and December 1996. After surgery, all infants were included in a 6-week follow-up examination.

During this period, 144 infants under 6 months of age underwent inguinal hernia repair. There were 114 males and 30 females. Fourteen patients had bilateral hernias at the time of presentation. Incarceration occurred in 32 infants (22%), that is in 27 of the 99 full-term cases (27%) and in 5 of the 45 preterm cases (11%). Only in three cases (8%) did it occur while the infant was awaiting repair. Over 90% of the full-term infants had their hernias repaired within 3 weeks from diagnosis. After reduction of incarceration, our policy is to operate within 24 to 48 hours. Four testicles appeared to be ischemic; one of these was excised. Patchy bowel ischemia was present in six cases, and bowel resection was required in one. The ovary and tube were twisted and ischemic at the time of operation, requiring oophorectomy in two female infants. Forty-five infants were premature. The mean age at the time of diagnosis was 8 weeks; at the time of herniotomy, it was 13 weeks. In the 24- to 28-week group, 44 of hernias were bilateral, and 7 of the 9 infants had been ventilated for an average of 6 weeks. The mean interval between diagnosis and surgery was 8 weeks for this group.

The management of an apparently simple condition such as pediatric inguinal hernia can prove difficult. Deaths have occurred after complications or surgery for inguinal hernia, and most are probably avoidable (9). Morbidity is common and primarily related to incarceration or to damage to vas or testicular vessels during a difficult herniotomy. Because of our policy to operate within 3 weeks from diagnosis, only 8% of incarcerations occurred in infants known to have inguinal hernia. It is surprising that 35% to 41% of incarcerations repeatedly occur in already diagnosed cases (10, 11). Our policy of operating within 24 to 48 hours of manual reduction of incarceration would avoid the 40% reincarceration rate still being reported (6, 10). Our recurrence rate of 2% (3 cases) in comparison to that of other reports (5.4%) (12) we consider acceptable. Because only 5% of cases developed a contralateral hernia, the contralateral exploration is unnecessary. Testicular atrophy has been reported in 1%, even after routine herniotomy (13). There was a large number of premature infants (31%) in our series; the typical range is 9% to 21% (1, 4). The incidence of bilaterality (44%) in this group is very high. The explanation could be that hernias may be caused by ventilation-induced positive intraabdominal pressure, which keeps the processus vaginalis open. Contrary to contemporary belief (1), we found that incarceration is less common in preterm (11%) than in full-term infants (27%).

The waiting period for premature infants is not hazardous, and herniotomy can be safely performed once the baby is mature (gestational age of 38 to 40 weeks), weighing more than 2200 grams, and is ready for discharge from the neonatal unit.