Infection and labor: VII. Microbial invasion of the amniotic cavity in spontaneous rupture of membranes at term

Objective: The purpose of this study was to determine the frequency, microbiologic characteristics, and clinical significance of microbial invasion of the amniotic cavity in women with premature rupture of membranes at term.
Study design: Amniocentesis was performed in 32 women with term premature rupture of membranes and amniotic fluid cultured for aerobic and anaerobic bacteria and Mycoplasmas.
Results: The prevalence of positive amniotic fluid cultures was 34.3% (11/32). The most common isolates were Ureaplasma urealyticum, Peptostreptococcus sp., Lactobacillus sp., Bacteroides fragilis, and Fusobacterium sp. Clinical chorioamnionitis occurred only in one patient with a positive amniotic fluid culture. Her neonate had ophthalmitis. Three patients (9.4%) had endometritis. Among women who were delivered vaginally, those with a positive amniotic fluid culture had a significantly higher rate of endometritis than those with a negative culture (33% [3/9] vs 0% [0/20], respectively, p = 0.023).
Conclusions: These data indicate that microbial invasion of the amniotic cavity occurs in approximately one third of patients with preterm premature rupture of membranes. Microbial invasion of the amniotic cavity is a risk factor for endometritis in women with term premature rupture of membranes.