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

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.

Assessment of transcervical chorion villus aspiration biopsy in early pregnancy.

BACKGROUND. Chorionic villus sampling for prenatal diagnosis is a relatively new technique and variable success rates have been reported by different authors depending on the methods and instruments used. We describe our experience with chorionic villus sampling in Bombay. METHODS. The procedure was attempted on 62 women before termination of their pregnancy via the transcervical route, under constant real-time ultrasound guidance. A metallic cannula was negotiated through the cervix into the uterine cavity to reach the chorionic frondosum and chorionic villi were aspirated by creating a negative pressure in the syringe attached to the cannula. The villus tissue was checked under a dissecting microscope. We calculated the success rate for obtaining a sample depending on the site of the chorionic frondosum, the physique of the mother, the position of the uterus and the size of the cannula. RESULTS. Villus tissue was aspirated in 47 of the 62 cases. The success rates of sampling at the first and second attempts were 48% and 27% respectively. The factors which were associated with a higher success rate were when the chorionic frondosum was situated posteriorly rather than anteriorly (61% v. 48%; p < 0.01), when the patient was thin rather than fat (58% v. 25%; p < 0.001), when the uterus was anteverted rather than retroverted (53% v. 41%). The commonest complication was bleeding which occurred in 15% of patients. CONCLUSION. Transcervical chorionic villus sampling is associated with a high success rate except in fat women with a retroverted uterus and in those with the chorionic frondosum situated in the fundus.

Studies on the prenatal chromosomal analysis and the changes of maternal serum alpha-fetoprotein following chorionic villus sampling

Transcervical chorionic villus sampling (CVS) was performed in 174 patients between 7 & 12 menstrual weeks of pregnancy opting for prenatal diagnosis. Advanced maternal age was the most common indication for CVS (39.7%). The sampling success rate was 95.4% (166/174), representing 88.9% at 7 to 8 weeks, 98.9% at 9 to 10 weeks & 92.7% at 11 to 12 weeks gestation. In 139 of 174 patients (80%), successful sampling was accomplished in one or two catheter passages only. Four spontaneous fetal losses (2.3%) occurred. The cytogenetic analysis routinely used was the direct overnight & long-term culture methods which revealed 4 abnormalities (2.4%). To date, 90 of the women have been delivered & all infants are doing well and the remaining 65 pregnancies are continuing uneventually. Maternal serum alphafetoprotein (MSAFP) concentration was determined in 72 patients immediately before & after CVS. A significant increase of 20% or more, comparable to pre CVS levels, was noted immediately after sampling in 56 of 72 patients (77.8%). The increase in MSAFP concentration correlated with the amount of villi sampled (r = 0.498, p less than 0.001) & with the number of sampling attempts (p less than 0.05). Estimated CVS related fetomaternal hemorrhage (FMH) ranged from 0.005 to 0.1552 ml and in 5 of 72 patients (6.90%) 0.06 ml or more of FMH was noted. Two of the 5 patients had FMH of 0.1 ml or more.