Prevalence of Mycoplasma bacteria in amniotic fluid at the time of genetic amniocentesis using the polymerase chain reaction.

OBJECTIVE: To use the polymerase chain reaction (PCR) to detect the presence of bacteria and Mycoplasma in amniotic fluid at the time of genetic amniocentesis and to assess their relationship to amniotic fluid interleukin-6 (IL-6) concentration and preterm delivery. STUDY DESIGN: A prospective study was performed on 78 asymptomatic pregnancies presenting for genetic amniocentesis. Amniotic fluid samples were analyzed by PCR for the detection of bacterial 16S ribosomal RNA, by PCR/enzyme-linked immunosorbent assay (ELISA)for Mycoplasma and by ELISA analysis for IL-6 concentration. RESULTS: All 78 samples were analyzed, and bacterial RNA was detected in 18% of them. However, no sample tested positive for Mycoplasma. The mean IL-6 concentration was 435 pg/mL. There was no difference in IL-6 levels or gestational age between bacteria-positive and -negative groups. CONCLUSION: Amniotic fluid may not be sterile in the midtrimester, yet the presence of bacteria, as detected by PCR, does not always result in an inflammatory response or adverse perinatal outcome.