Background: Microbial invasion of amniotic cavity occurs in 30 to 50% of patients with premature membrane rupture.
Aim: To determine the outcomes associated with microbial invasion of the amniotic cavity (MIAC) in patients with preterm premature rupture of membrane (pPROM).
Patients and methods: One hundred thirty four patients with preterm pPROM between 24 and 34 weeks of pregnancy, without clinical infection or labor, were studied. Cultures were obtained by transabdominal amniocentesis from the amniotic fluid and the lower genital tract. Four groups of MIAC were observed: MIAC1: due to S. agalactiae, F. nucleatum or H. influenzae as only etiologic agents, MIAC2: due to other bacteria, alone or mixed, MIAC3: due to U. urealyticum as only etiologic agent, MIAC0: No MIAC and no infection of the lower genital tract. Study patients received antibiotics and were managed expectantly until 35 weeks unless clinical chorioamnionitis developed or an amniotic fluid culture returned positive for S. agalactiae, F. nucleatum or H. influenzae.
Results: Ninety six patients were enrolled: MIAC1 (n=11), MIAC2 (n=30), MIAC3 (n=19) and MIAC0 (n=36). Clinical chorioamnionitis was more common in patients with MIAC1 than those with MIAC3 (p<0.01) and those without infection (p<0.001). The admission to delivery interval was shorter in patients with MIAC1 (2.8 days) than those with MIAC3 (10.1 days, p<0.05) and those without infection (18 days, p<0.001). Delivery within 48 h and within 7 days of admission were also more frequent in patients with MIAC1 than in patients with MIAC3 (p<0.05) or those without infection (p<0.001). Newborns to mothers with MIAC1 had a higher frequency of infection (36%), asphyxia (36%), admission to neonatal ICU (100%) and death (46%) than those of mothers with MIAC3 and those without infection. Birth weight was also significantly lower. Histological chorioamnionitis was more common in patients with MIAC1 than in patients with MIAC3 and those without infection. The rate of funisitis was higher in patients with MIAC1 than those without infection.
Conclusions: In patients with preterm PROM, microbial invasion of the amniotic cavity by S. agalactiae, F. nucleatum or H. influenzae is associated with high frequency of adverse maternal and neonatal outcomes and neonatal death.