[Twin pregnancy discordant for trisomy 13: three cases].

BACKGROUND: The association between Patau's syndrome and multiple pregnancy is extremely rare. This paper reports three cases with different obstetric treatment. CASE 1: Dichorionic diamniotic twin pregnancy with a fetus affected by trisomy 13 diagnosed at 16 weeks of gestation. The pregnancy was managed conservatively resulting in the delivery of twins at 38 weeks. The structurally normal twin was male survived without sequelae, but the female fetus with trisomy 13 died shortly after delivery. CASE 2: Dichorionic diamniotic twin pregnancy. At 14 weeks of pregnancy, one of the fetus affected by trisomy 13 showed an early intrauterine growth restriction and a cystic hygroma. At 16 weeks of pregnancy the abnormal twin died spontaneously. Avaginal delivery occurred at 38 weeks being born a healthy male. CASE 3: Dichorionic diamniotic twin pregnancy. The trisomy 13 fetus had been diagnosed at 17 weeks of pregnancy and showed a cardiopathy. At 32 weeks of gestation a selective fetal reduction was performed. Vaginal delivery occurred at 35 weeks and a healthy newborn was born. CONCLUSION: Patau's syndrome has an unfortunate fetal and neonatal outcome. It is important an early diagnosis to establish the best strategy to minimize the risk of the healthy twin.