First trimester prenatal diagnosis by transcervical chorionic villus sampling using curved biopsy forceps: lessons of the first 30 continuing pregnancies.

ABSTRACT

Transcervical chorionic villus sampling was performed on 30 pregnancies who were at risk for chromosomal abnormalities between 9 and 12 weeks of gestation to determine whether the developing fetus had a chromosomal disorder. Curved biopsy forceps were passed transcervically into the chorion frondosum under continuous real-time ultrasound guidance, and chorionic villi were biopsied. Chorion yield was assessed semiquantitatively. An adequate villus sample was obtained in all cases, giving a success rate of 100 per cent. The average weight of the villi was 18.8 mg with a lower limit of 10 mg which proved sufficient for diagnostic purposes. The villi were processed for chromosomal analyses by cultured preparations. A diagnostic result was achieved in 28 of cases (93.3%) within 2 weeks. No major maternal complications were encountered. The fetal loss rate was 3.3 per cent. No fetal anomalies were found in the study group. It is concluded that transcervical chorionic villus sampling appears to be a relatively safe and reliable procedure, but the risk of miscarriage can only be accurately assessed after further investigation. In contrast to amniocentesis, the procedure is performed early in pregnancy and results of the genetic test are available during the first trimester. We believe that transcervical chorionic villus sampling offers an alternative to amniocentesis in the detection of genetic disorders.