Dichorionic twins discordant for thanatophoric dysplasia managed with selective reduction at 20 weeks' gestation: A case report

BACKGROUND: Thanatophoric dysplasia (TD) is a rare and lethal form of skeletal disorder. A MEDLINE search for 1965-2003 yielded only 3 reports of multiple pregnancies discordant for TD. This is the first case report of selective twin reduction for this diagnosis. CASE: A young woman was seen in consultation at 20 weeks' gestation. Ultrasound examination revealed a twin pregnancy, with ultrasound markers consistent with thanatophoric dysplasia, type II, in twin A. A thick dividing membrane and separated placentas were noted. After counseling, the patient opted for selective termination of twin A. Termination was performed by intracardiac injection of potassium chloride. The pregnancy continued uneventfully until 33 weeks, when spontaneous labor resulted in vaginal delivery of a vigorous female infant, and a mummified, macerated fetus. CONCLUSION: Selective termination for discordant lethal anomalies can be safely performed when the presence of the anomalous twin increases the risk of a poor perinatal outcome for the apparently normal cotwin.