Prenatal diagnosis. A preliminary study of first-trimester chorionic villous biopsy.

Biopsy of the developing placenta before the thirteenth gestational week was performed by transcervical cannula aspiration guided by real-time ultrasound in 21 consecutive patients. Chorionic villi were obtained in 20 patients and chromosomal analysis was possible in 19. One significant complication occurred: perforation of one gestational sac in the only patient in the series with a twin pregnancy. More studies are required in order to provide an adequate assessment of the risk--of fetal loss, culture failure and trophoblastic chromosomal abnormalities not representative of the mature fetus--associated with the technique. In practised hands, the procedure may provide a preferable and safe alternative to amino-centesis and fetoscopy for the prenatal diagnosis of genetic defects.