Distribution of fetal erythroblasts in maternal blood after chorionic villous sampling

Abstract

Objective: To investigate whether chorionic villus sampling (CVS) is associated with an increase in fetomaternal cell trafficking. Design: Prospective study. Setting: King's College London School of Medicine, King's College Hospital. Sample: Eighteen singleton pregnancies undergoing CVS for fetal karyotyping at 11-14 weeks of gestation and subsequently found to have chromosomal defects. Method: Maternal blood samples were obtained immediately before and at 3-14 (median 5) days after CVS. Fetal erythroblasts were isolated using triple density gradient separation and anti-CD71 magnetic cell sorting techniques. The enriched erythroblasts were stained with Kleihauer-Giemsa and with fluorescent antibodies for the epsilon (ε) and gamma (γ) globin chains. The percentage of fetal cells positive for each stain was calculated. Fluorescence in situ hybridisation (FISH) for X- and Y-chromosomes was also performed. Comparison was made in the proportion of enriched fetal cells between the pre-CVS and post-CVS samples. Main outcome measures: The proportion of fetal erythroblasts in maternal blood. Results: The percentage of erythroblasts enriched from maternal blood that stained positive for ε and γ globin chains and with Kleihauer-Giemsa was significantly higher in the post-CVS samples compared with the pre-CVS samples. FISH analysis for the Y-chromosome confirmed the increase in fetal cell proportion in the post-CVS samples. The percentage difference in fetal cells decreased significantly with time interval from CVS. Conclusion: CVS results in an increase in fetomaternal cell trafficking, which continues to be present for several days after the procedure.