Antibiotic administration in patients with preterm premature rupture of membranes reduces the rate of histological chorioamnionitis: a prospective, randomized, controlled study.

OBJECTIVE

To determine whether antibiotic administration in patients with preterm premature rupture of membranes is associated with a reduction in the rate of histological chorioamnionitis and funisitis.

METHODS

One hundred consecutive patients with preterm premature rupture of membranes and no labor between 24 and 34 weeks were invited to participate in this study. Eligible patients randomly received either clindamycin-gentamicin for 7 days or placebo, and were managed expectantly until 35 weeks unless fetal or maternal indications developed. Microbial invasion of the amniotic cavity was defined as the presence of a positive amniotic fluid culture obtained by transabdominal amniocentesis. Cervicovaginal infection was diagnosed when bacterial vaginosis or a positive culture for cervicovaginal pathogens or facultative bacteria associated with a significant increase in the white blood cell count were found. Histological chorioamnionitis was based on the observation of polymorphonuclear leukocyte infiltration of the chorionic plate or the extraplacental fetal membranes. Funisitis was diagnosed in the presence of polymorphonuclear leukocyte infiltration into the umbilical vessel walls or Wharton jelly. Statistics were performed using contingency tables.

RESULTS

Seventy-one patients with available histological study of the placenta were included. Thirty-five women received antibiotics and 36 were given placebo. Patients who received antibiotics had a significantly lower rate of histological chorioamnionitis than patients who received placebo (46% (16/35) vs. 69% (25/36), respectively; p < 0.05). This effect was more pronounced among women with microbial invasion of the amniotic cavity and/or cervicovaginal infection (58% vs. 89%, respectively; p < 0.01). Antibiotic therapy was associated with an increase in the frequency of placentas without histological abnormalities (29% vs. 6%; p < 0.01). The frequency of funisitis was not different between groups.

CONCLUSION

Administration of antibiotics in patients with preterm premature rupture of membranes is associated with a significant reduction in the incidence of histological chorioamnionitis but it does not modify the frequency of funisitis.