Effects of Urinary Trypsin Inhibitor in Patients at Risk for Premature Labor with a Bulging Fetal Membrane

Objective: To investigate the effect of urinary trypsin inhibitor (UTI) in patients at risk for premature labor with bulging membrane. Methods: Patients who had developed a bulging membrane from 22 to 27 weeks and 6 days of gestation were studied. These cases were divided into two types based on the severity: those with a moderately developed bulging membrane like a ‘dome’ (dome type), and those with a membrane prolapsed into the vagina, resulting in an ‘hourglass’ shape (hourglass type). We compared the outcomes of treatment with or without UTI (UTI group versus non-UTI group) in each type. Gestational age at delivery, birth weight, prolongation time from admission to delivery, and neonatal mortality rate were examined in each group. Results: A total of 43 patients with a bulging membrane were analyzed. In 21 patients with the dome type, gestational age at delivery (the UTI group versus the non-UTI group; 30.4 ± 5.0 versus 26.4 ± 1.9 weeks, p < 0.05), birth weight (1,436.8 ± 708.3 versus 882.8 ± 261.6 g, p < 0.05) and neonatal mortality rate (0/13 versus 3/8, p < 0.05) were all significantly improved by the use of UTI. On the other hand, in 22 patients with the hourglass type, there was no significant difference between the UTI group and the non-UTI group. The overall prevalence of histological chorioamnionitis was 60%. Conclusion: These results suggest that UTI therapy is very effective in patients at risk for premature labor with a moderately developed bulging membrane during the second trimester.