Non-invasive early prenatal diagnosis using fluorescent in situ hybridization on transcervical cells: comparison of two different methods for retrieval

Objective: We compared the efficiencies of uterine and endocervical lavage to retrieve fetal cells from first trimester pregnancies for further analys is with fluorescent in situ hybridization (FISH). Study Design: Transcervic al cell (TCC) samples were collected at 7-10 weeks of gestations by uterine lavage (13 women) and by endocervical lavage (12 women) who were scheduled for volunteer termination of pregnancy. A sample of placenta was also obta ined for cytogenetic analysis to confirm the sex or genotype in the end of the procedure. FISH was performed using probes for the chromosomes 18, X an d Y in a three color hybridization protocol. The statistical analysis inclu ded chi (2)-analysis, and t-test. Results: Sufficient cells were obtained i n 12 of the 13 (92.3%) in uterine lavage and 10 of the 12 (83.3%) in endoce rvical lavage group for FISH procedures for fetal sex prediction. The mean success rate of signal detection for FISH procedure was 91.7% (range 83-97% ). Fetal sex was correctly predicted in 11 of 12 (91.6%) with uterine lavag e and 8 of 10 (80.0%) in endocervical lavage and the difference was statist ically insignificant. Conclusion: This study demonstrated that there are av ailable cells of fetal origin in the lower part of the uterus and these cel ls may be collected successfully as early as 7 weeks of the gestation. In a ddition, our results show that endocervical lavage method is as effective a s uterine lavage. FISH has been successfully used to detect status of aneup loidy and sex of the fetus from TCC. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.