Bacteriology of Amniotic Fluid in Women with Suspected Cervical Insufficiency

Objective: To determine the prevalence of mid-trimester microbial invasion of the amniotic cavity (MIAC) in women with suspected cervical insufficiency.

Methods: A prospective observational cohort study was performed in women with suspected cervical insufficiency and visible fetal membranes who were undergoing amniocentesis to rule out MIAC between 16 and 26 weeks of gestation. Women with preterm premature rupture of membranes, regular uterine contractions, or who had a cervical cerclage were excluded. Gram staining of amniotic fluid, glucose and lactate dehydrogenase (LDH) levels in amniotic fluid, and aerobic and anaerobic amniotic fluid cultures were performed, along with polymerase chain reaction (PCR) for the detection of Ureaplasma and Mycoplasma species.

Results: Fifteen women with a mean gestational age of 22.6 +/- 2.3 weeks were included in the study. The diagnosis of MIAC was confirmed in 47% (7/15), of whom 20% (3/15) were infected with more than one bacterial strain and 33% (5/15) with Ureaplasma species. According to receiver-operator curve analyses, amniotic fluid levels of glucose were associated with MIAC (P = 0.02), but not amniotic fluid LDH (P = 0.25).

Conclusion: MIAC is present in approximately one half of women with suspected cervical insufficiency and visible fetal membranes at speculum examination.