SINGLE UTERINE ENTRY FOR GENETIC AMNIOCENTESIS IN TWIN PREGNANCIES

In 176 diamniotic twin pregnancies at 10-20 weeks of gestation, amniot ic fluid for cytogenetic studies was successfully obtained from both s acs by the use of a single uterine entry. There were no cases of disco rdancy between sex at amniocentesis and birth. There were six pregnanc ies with fetal unbalanced chromosomal defects; in one pregnancy both f etuses were abnormal and in five pregnancies only one fetus was abnorm al. The total fetal loss rate was 5.7% (20 of 352 fetuses), including six (1.7%) terminations or selective fetocides and 14 (4.0%) spontaneo us deaths. In the 176 Pregnancies there were five (2.8%) with no survi vors, including one termination and four (2.3%) spontaneous miscarriag es or intrauterine deaths. There are only two (1.1%) Pregnancies in wh ich amniocentesis could have contributed directly to the losses and th erefore the procedure-related rate of fetal loss may be similar to tha t in singleton pregnancies. The median gestation at delivery was 37 (r ange 16-40) weeks and delivery before 32 weeks occurred in 9% of the p regnancies. The birth weight distribution was similar to that reported in singleton pregnancies. This study demonstrates that in twin pregna ncies amniotic fluid for cytogenetic studies can be obtained successfu lly from both sacs by use of a single uterine entry. The risk of fetal loss from this procedure appears to be similar to that in singleton p regnancies.