Dilemmas in the management of twins discordant for anencephaly diagnosed at 11 + 0 to 13 + 6 weeks of gestation.

OBJECTIVE To help develop an evidence-based approach to the best management of twin pregnancies discordant for anencephaly. METHODS We retrospectively examined the management and outcome of 18 pregnancies discordant for anencephaly diagnosed at 11 + 0 to 13 + 6 weeks of gestation in our center. We combined these data with those from other publications. In total, there were 44 dichorionic pregnancies that were managed expectantly (n = 35) or by selective feticide (n = 9) and 19 monochorionic pregnancies that were managed expectantly. We also reviewed the literature to ascertain the outcome of monochorionic twin pregnancies undergoing cord occlusion. RESULTS In the 35 dichorionic pregnancies that were managed expectantly, 20 (57.1%) developed polyhydramnios at 25-31 weeks; 13 were managed expectantly, five had amniodrainage and two had selective feticide. In 34 of the 35 cases the non-anencephalic twin was liveborn at a median gestation of 36 (range, 28-39) weeks and in six (17.6%) of these it was born before 33 weeks. In the dichorionic pregnancies that had selective feticide, there was one miscarriage and eight (88.9%) live births at a median gestation of 37 (range, 30-40) weeks and in one (12.5%) of these it was born before 33 weeks. In the monochorionic pregnancies, four (21.1%) anencephalic fetuses died at 20-32 weeks and in three of these the normal co-twin also died. In the 16 (84.2%) cases resulting in the live birth of the normal twin, delivery occurred at a median gestation of 33 (range, 27-39) weeks and in six (37.5%) of these it was before 33 weeks. Ultrasound-guided bipolar cord coagulation in 92 pregnancies, mostly complicated by twin reversed arterial perfusion sequence or severe twin-to-twin transfusion syndrome, was associated with a survival rate of 77.2% and early preterm delivery rate of 31.0%. CONCLUSION Dichorionic twins discordant for anencephaly are best managed with serial ultrasound examinations for early diagnosis of polyhydramnios, which can then be treated either by amniodrainage or selective feticide. In monochorionic twins it is uncertain whether the best management is expectant or by cord occlusion.