Objective: To evaluate the accuracy and risk of chorionic villus sampling (CVS) for prenatal diagnosis in multiple pregnancies.
Method: Twenty-eight chorionic villus samplings were carried out in a group of women with twin pregnancies. A transabdominal route was chosen in 24 samplings and the rest (four samplings) were carried out in a transcervical route. In the group of women with triple pregnancies, 14 tests were performed in a transabdominal route and one in a transcervical route.
Results: No sampling failure occurred. One laboratory failure occurred in a triplet pregnancy, and one abnormal karyotype (47,xy+18) was found in the group of 28 twin fetuses. The rest of the fetuses in this group had normal karyotypes. Of the five triplets, two chromosomal abnormalities were diagnosed: a mosaic 46,xy/47,xxy was found in both cases. One fetus was affected by fragile -x syndrome. Selective reduction of the affected fetuses was carried out. There was no spontaneous fetal loss. Fetuses which were found to have normal prenatal tests were also found to be normal when born.
Conclusion: In this relatively small series of CVS in twins and triplets, the procedure has been proven to be safe and reliable for prenatal diagnosis.