Detection of cells of fetal origin from transcervical irrigations

Twenty-one women (age range 17-38 years) undergoing termination for social reasons in the first trimester were selected. Ultrasound determined the gestation and placental site. A commercially available flexible, sterile plastic tube was advanced to the level of the internal os. Five to eight millilitres of normal saline was injected and then gently aspirated into the tube. Chorionic villus sampling (CVS) or amniocentesis was subsequently performed for back-up sexing. Commercial X and Y probes were used simultaneously for fluorescence in situ hybridization (FISH) study of the cervical washing and back-up samples, XY signals were observed in 10 out of 12 male fetuses and 1 out of 4 female fetuses (false positive), indicating 81.3 per cent correct prediction. Four cervical washing samples did not provide enough cells for FISH. The frequency of cells showing XY signals varied from 3.6 to 47.8 per cent in male-predicted pregnancies. Placental-location, gestational age, or maternal age did not affect the successful retrieval of fetal cells. Trophoblast cells were obtained in a significant number (83 per cent) of pregnant women with male pregnancies by transcervical irrigation in the first trimester. This preliminary part of the study shows the presence of fetal cells in the transcervical samplings and the feasibility of FISH in detecting them; however, further studies are needed to isolate and purify fetal cells.