Occult Intraamniotic Infection at the Time of Midtrimester Genetic Amniocentesis: A Reassessment

OBJECTIVE The objective of this study was to reevaluate the incidence of occult early midtrimester intraamniotic infection in asymptomatic patients at the time of genetic amniocentesis. METHODS A total of 177 amniotic fluid (AF) specimens from patients referred for genetic amniocentesis between 15 and 20 postmenstrual weeks were evaluated for the presence of bacteria by detailed light microscopy, after Gram and Wright stain, and by cultures for aerobic and anaerobic baceria, Mycoplasma sp., and Ureaplasma urealyticum. Seventy-seven AF specimens were also tested for the presence of bioactive leukoattractants by a leukotaxis bioassay. RESULTS All fluids were negative for bacteria and bioactive leukoattractants [95% confidence interval (CI), 0-1.9%; 99% CI, 0-2.9%]. This is significantly less than a recently reported incidence of 5.09% (P = 0.002). Incidentally, artifacts with light microscopic morphology consistent with spermatozoa were found during the detailed light microscopic evaluation of AF Gram stains from 2 (1.1%) AF samples in otherwise uneventful pregnancies, a previously unreported finding. Scanning electron microscopy was used to confirm the light microscopic findings. CONCLUSIONS Occult intraamniotic infection in the second trimester is not as high as recently reported. AF culture in all cases of second-trimester amniocentesis is not necessary. The identification of spermatozoa on Gram stain of second-trimester AF specimens needs further confirmation.