Analysis of the significance of discolored amniotic fluid detected at midtrimester amniocentesis.

In 110 midtrimester amniocenteses of the 3349 procedures done at the University of California, Davis, Medical Center between 1979 and 1984, the fluid obtained was noted to be discolored. The significance of this finding was evaluated with review of pregnancy history and outcome and by using biochemical techniques. A significant increase in miscarriage was seen in the pregnancies where discolored fluid was obtained (9%), in comparison with the entire group of pregnancies in which amniocentesis was done at the same institution over the same period (1.6%). This increase was most marked in the pregnancies in which, in addition to discolored fluid, there was a prior history of pregnancy bleeding. Thirty-four discolored fluid samples and 18 clear fluid samples were studied with spectrophotometry, electrophoresis, isoelectric focusing, and chromatography. These studies indicate that in most cases the discoloring pigment is blood rather than fetal bowel contents, as had been suggested by others.