Coelomic fluid analysis: the absolute necessity to prove its fetal origin

Coelocentesis may represent the ideal technique for early prenatal diagnosis. This study aimed to quantify the number of cells in coelomic fluid and to investigate the feasibility of interphase fluorescence in-situ hybridization (FISH) in uncultured coelomic cells for chromosomes X and Y in 12 samples of 0.4-0.8 ml of coelomic fluid obtained by transvaginal puncture at 8-9 weeks of gestation. It was found that the density of cells in the coelomic fluid was low and variable ranging from 0 to 10,600 cells/ml. The FISH analysis failed in three cases because of the absence or remarkably low number of cells. Among the remaining nine cases, FISH analysis led to an unambiguous result in all the samples except two in whom the FISH analysis clearly demonstrated a high count of maternal cells whereas the fluid was apparently not blood stained. The presence of such maternal cells, while their source and nature remaining unexplained, stressed the question of the absolute necessity to prove the fetal origin of the cells analysed. Whatever the cytogenetic analysis performed on coelomic fluid, combining a systematic exclusion of significant maternal contamination is recommended, using multiplex polymerase chain reaction for short tandem repeat analysis to cytogenetic analyses.