Inguinal hernia in preterm infants (≤32-week gestation)

The current incidence of inguinal hernia (IH) in premature infants is not well-established. It is also unclear whether common co-morbidities in this population, i.e., chronic lung disease (CLD) or nutritional status or both contribute to the development of IH. The purpose of this study was to establish the epidemiologic profile of preterm infants of 32 weeks gestational age (GA) or less at birth with IH and determine whether the severity of CLD or poor nutritional status predisposes to the development of IH. Perioperative profiles of infants undergoing surgery were also reviewed. A retrospective study of 1,057 infants born at 23-32 weeks GA from January 1990 to December 1995 was done. Specific risk and demographic factors were identified. Factors used to determine severity of CLD were: days on intermittent mandatory ventilation (IMV); days on positive pressure (IMV + continuous positive airway pressure); and total number of days on supplemental oxygen. Overall nutritional status was determined by weight gain in g/kg per day. The incidence of IH in preterm infants of 32 weeks GA or less who were admitted for 28 days or more was 9.34% (65/696) prior to discharge. The incidence in infants weighing 1,500 g or less was 11.11% (63/567) and in infants 1,000 g or less 17.39% (48/276). All parameters that deter-mined the severity of CLD were statistically significant in infants with IH by univariate analysis. In a multivariate regression model, male gender was the most important variable that was significantly associated with IH (odds ratio OR = 9.6; 95% confidence interval Cl = 3.90-23.59), followed by total days on supplemental oxygen (adjusted OR = 1.00; 95% CI = 1.01-1.02). Weight gain (g/kg per day) was not significantly different between the two groups. Surgical correction before discharge was well tolerated. We conclude that the incidence of IH is GA-dependent. Factors related to severity of CLD play a more important role than weight gain in predisposing to IH.