FIRST TRIMESTER CHORIONIC VILLUS SAMPLING IN TWIN GESTATIONS

First-trimester prenatal diagnosis was offered to 104 twin pregnancies mainly for advanced maternal age and cytogenetic evaluation of a new fertilization technique. Chorionic villus sampling (CVS) was performed transcervically (35%), transabdominally (23%), or by combination of t hese two techniques (42%). Although no placental biopsy failures occur red, two errors in fetal sexing were recorded due to non-selective pla cental sampling. In these two cases, both fetuses were sampled transce rvically. Cytogenetic results were available for all fetuses; six of t hem showed an abnormal direct chromosomal pattern, but long-term villi culture analysis or additional amniocentesis (n = 1) reduced the numb er to four. Early fetal loss (3.4%) and perinatal mortality (6.3%) aft er CVS were comparable with a control group of 101 consecutive twin pr egnancies without prenatal diagnosis (respectively 6.9% and 5.3%). Per inatal loss in the CVS group was associated in 10 of 12 fetuses with p reterm premature rupture of the membranes and consequent preterm deliv ery. Mean gestational age at delivery, mean birthweight and the freque ncy of preterm delivery and low birthweight infants were nearly identi cal in both groups. This study shows that CVS in the first trimester o f pregnancy is an accurate and fast approach for prenatal diagnosis in twin gestations with an acceptable risk of adverse pregnancy outcome. However, a transcervical approach for both fetuses is not recommended .