Objective: We compared the efficiencies of uterine and endocervical lavage to retrieve fetal cells from first trimester pregnancies for further analysis with fluorescent in situ hybridization (FISH).
Study design: Transcervical 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 obtained 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 and Y in a three color hybridization protocol. The statistical analysis included chi(2)-analysis, and t-test.
Results: Sufficient cells were obtained in 12 of the 13 (92.3%) in uterine lavage and 10 of the 12 (83.3%) in endocervical 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 lavage and 8 of 10 (80.0%) in endocervical lavage and the difference was statistically insignificant.
Conclusion: This study demonstrated that there are available cells of fetal origin in the lower part of the uterus and these cells may be collected successfully as early as 7 weeks of the gestation. In addition, our results show that endocervical lavage method is as effective as uterine lavage. FISH has been successfully used to detect status of aneuploidy and sex of the fetus from TCC.