Significance of brown and/or green amniotic fluid at the time of second trimester genetic amniocentesis

During a two-year period, 83 discolored fluids (77 green, six brown) were obtained during genetic amniocenteses of 1227 patients. When compared with case-matched control subjects, those patients with discolored fluid had no differences in the incidence of spontaneous abortions, abnormal fetal karyotypes, infant abnormalities, occurrence of preterm labor, or requirement for delivery by cesarean section. The only statistically significant difference between control and test patients was that one in 83 versus 32 of 83 reported bleeding before amniocentesis (P <.001). Both green and brown fluids had spectrophotometric peaks at 400 to 408 nm, similar to that reported for meconium. However, discolored fluid had measurable free hemoglobin, whereas meconiumstained fluid from term gestations did not, suggestive of an in utero hemorrhage. Further, when fetal blood, in concentrations calculated to yield a hemoglobin content similar to those measured in the discolored fluids, was incubated in amniotic fluid the spectrophotometric peak and absorbance units at 400 to 408 nm were similar to those for the discolored fluids. These observations are supportive of the hypothesis that blood breakdown products from an episode of intrauterine bleeding are responsible for the discolored fluid. Discolored amniotic fluid during second trimester, as an isolated finding, does not prognosticate a poor pregnancy outcome.