In the last 15 years, 372 patients with multiple preg­nancies underwent genetic amniocentesis, of which 365 were twin pregnancies. One was lost to follow-up, 15 are ongoing pregnancies, and we present the data on 347 preg­nancies. All patients has an ultrasound examination before the procedure in order to localize the placental site, the fetal position and to determine chorionicity.

The procedure was performed between the 11^th and 23^rd weeks’ gestation (mean gestational age 17.2 weeks). In seven cases, amniocentesis was performed before 14 completed weeks (first trimester amniocentesis) and in the remaining 340, between the 16^th and 23^rd week (second trimester amniocentesis) under ultrasound guidance. Pa­tients were 19-52 years old (mean maternal age 36.18 years).

All procedures were performed with the double entry technique, using a 22 gauge needle, and 20 mL of amni­otic fluid was successfully withdrawn from each sac. In 96 cases, both placentas were posterior, in 110 cases, both placentas were anterior, and in the remaining 141 there was one anterior and one posterior placenta. The rates of miscarriage were 2.08% (2/96).

In the group of 340 second trimester amniocentesis, two pregnancies were terminated [one because of homozy­gous b-thalassemia (thal) and one because of severe TTTS]. Six women underwent selective feticide (two because of trisomy 21, one because of 47XXX, two be­cause of homozygous b-thal and one because of neural tube defect). One patient delivered a healthy live birth at 30 weeks and there was one neonatal death of a term baby due to a congenital heart defect. In this group 62.5% of pregnancies resulted in one live birth.

In the 332 remaining second trimester amniocentesis patients there were 14 miscarriages (4.21%), half of which occurred in the first 3 weeks after the procedure. The rate of pre-term delivery, before 32 weeks and before 35 weeks, was 11.94 and 32.07%, respectively. The perinatal loss rate, before and after 28 weeks, was 5.87 and 3.20%, respectively. The neonatal mortality rate, before and after 28 weeks, was 1.26 and 1.78%, respectively. Of the 332 pregnancies 94.58% resulted in at least one live birth.

During the same period, 74 CVS procedures were performed in multiple pregnancies. Six cases were lost to follow-up and we present the data of the remaining 38 cases. The procedure was performed transabdominally in all cases between the 9^th and 15^th week of gestation (mean maternal age 30.7 years, and the rate of repeat procedure was 11.76% (8/68). Five procedures were performed in pregnancies with more than two fetuses (four triplets and one quadruplet pregnancies) and the indications were b-thal [4] and advanced maternal age [1]. There were six fetuses affected by homozygous b-thal and two fetuses affected by trisomy 21; in all cases selective feticide was carried out at less than 14 weeks’ gestation. In this group, there were two spontaneous abortions at 20 and 21 weeks’ gestation (40%), and one patient delivered prematurely at 34 weeks (33.33%).

Chorionic villus sampling was were performed in 63 twin pregnancies. The indications were increased risk of chromosomal abnormality in 10 cases (includes advanced maternal age, anxiety, increased nuchal translucency and family history of trisomy 21), and increased risk of genetic syndromes of structural anomalies in 53 women (Du­chenne syndrome, plenylketonuria, b-thal, structural anomalies).