Presence of cell-free fetal DNA in plasma of women with ectopic pregnancies.

BACKGROUND The quantity of cell-free fetal DNA in the plasma of pregnant women changes during pregnancy and seems to be different in normal and pathologic pregnancies. We investigated the possible diagnostic applications of the detection and measurement of cell-free fetal DNA by comparing quantities found in women with ectopic (EP) or intrauterine (IUP) pregnancies. METHODS We collected blood samples from 58 women who had positive pregnancy tests and specific complaints and sonographic findings suggestive of EP and from 45 women with confirmed IUP. We performed quantitative real-time PCR analysis of the sex-determining region Y (SRY) gene to detect and measure the amount of cell-free fetal DNA. The diagnosis of EP was confirmed by histologic examination. RESULTS SRY was detected in 15 EP and 14 IUP cases. The mean (SD) amount of cell-free fetal DNA was significantly higher (P<0.005) in women with EP [565 (136) genome-equivalents (GE)/mL] than in women with IUP [72 (19) GE/mL] at the same gestational age. CONCLUSIONS Our results confirm that cell-free fetal DNA is present in plasma of women with EP. The finding of higher amounts of cell-free fetal DNA in EP cases than in IUP cases suggests that this method might be useful for early diagnosis of EP.