Fetomaternal hemorrhage in relation to chorionic villus sampling revisited

OBJECTIVE: To investigate whether chorionic villus sampling (CVS) results in a proportional increase of alpha-fetoprotein (AFP) and fetal red cells in maternal blood. METHODS: Blood samples were collected before and after CVS. The AFP concentration was measured and supervised automated microscopy of Kleihauer-Betke slides was applied to quantify fetal red cells. RESULTS: AFP analysis was performed in 53 paired samples and automated microscopic scanning in 59 paired samples. Median AFP concentrations before and after CVS were 12.0 microg/L (range 6.4-36.4) and 18.7 microg/L (range 8.2-668.9), respectively, indicating a significant increase (p < 0.0001). Median numbers of fetal red cells detected before and after CVS were 0 (range 0-36) and 0 (range 0-31), respectively. No significant increase of fetal cells was observed (p = 0.72). The delta (Delta) fetal red cells and the Delta AFP correlated poorly (rho = -0.22, p = 0.11). The amount of villi correlated moderately with the Delta AFP (rho = 0.32, p = 0.02) and did not correlate with the Delta fetal red cells (rho = -0.11, p = 0.43). CONCLUSIONS: Although the AFP concentration after CVS increased, no increase of fetal red cells was detected. These findings suggest that CVS results in a leakage of proteins due to placental tissue damage, rather than increased trafficking of fetal cells.