Monoamniotic twins: Case series and proposal for antenatal management

Objective: To present a case series of antenatally suspected monoamniotic t win gestations managed by a similar set of guidelines. Methods: Eight women with antenatally suspected monoamniotic twins were ide ntified between 1994 and 1996 in a single perinatal referral area. All were diagnosed sonographically. Management included serial ultrasound studies, frequent nonstress testing, and weekly steroid therapy. Elective cesarean d elivery was recommended at 32 weeks unless obstetrically indicated at an ea rlier age. Results: Monochorionic monoamniotic twins were confirmed at delivery in six women, and one had a pseudo-monoamniotic twin. One woman was found to have a monochorionic diamniotic pregnancy at delivery. Of the eight women, thre e were delivered by elective cesarean at 32 weeks, including the falsely di agnosed case. Three were delivered before 32 weeks because of nonreassuring fetal testing. One was delivered at 25 weeks secondary to hemolysis, eleva ted liver enzymes, low platelets, and disseminated intravascular coagulatio n. One was delivered at 33 weeks, after declining elective delivery at 32 w eeks, because of death of one twin and nonreassuring testing of the other t win. Morbidity among the live-born infants included severe bronchopulmonary dysplasia (25-week twins), large-bowel perforation (30-week infant), and r espiratory distress syndrome and mild bronchopulmonary dysplasia (one 32-we ek pair). Conclusion: Monoamniotic twin pregnancies can be diagnosed reliably by ultr asound alone in most cases. Frequent antenatal testing may show signs of co rd compression that may prompt delivery but will not prevent sudden fetal d eath. Fetal death can occur at greater than 32 weeks' gestation despite int ensive fetal surveillance. Elective preterm delivery could be considered to eliminate the uncertain risk of fetal death. (C) 1999 by The American Coll ege of Obstetricians and Gynecologists.