[Early prenatal diagnosis using fetal cells acquired from different sites of uterine cervix: a preliminary study]

To compare the presence of fetal cells in the transcervical lavage fluids obtained at different levels of uterine cervix so as to evaluate the better sampling place for early prenatal diagnosis.

Sixty samples of transcervical lavage fluid were obtained at the level of the internal orificium of cervix of 60 women during the 5 - 10th week of pregnancy who underwent artificial abortion (internal orificium group), and 60 samples of transcervical lavage fluid were obtained at the level of the external orificium of cervix of 60 women the same age during the 5 - 10th week of pregnancy who underwent artificial abortion too (external orificium group). Extraction and amplification of DNA were conducted by females to detect the presence of SRY gene of Y chromosome. The sex of the fetus was determined by chromosome karyotyping of the villi.

(1) In the internal orificium group Y-derived sequences were detected in 71.4% (15/21) of the samples of known male pregnancy and 5.13% (2/39) cases of known female pregnancy, with a total correct sex prediction rate of 86.7%; In the external orificium group Y-derived sequences could be amplified in 37% (10/27) of the samples of known male pregnancy and 6.25% (2/32) of the samples of known female pregnancy, with a total correct sex prediction rate of 67.8%, significantly lower than that of the internal orificium group (P < 0.05). (2) The number of the copies of SRY gene of Y chromosome of the internal orificium group was 1487.17 +/- 430.45 copies, significantly higher than that of the external orificium group (702.41 +/- 365.71 copies, P < 0.05).

Transcervical cell sampling provides a promising approach for early non-invasive prenatal diagnosis. More fetal cells can be acquired at the internal orificium level of cervix than at the external orificium level, however, more non-invasive and efficient sampling method should be taken.