A rare combination of congenital anomalies following in utero methimazole exposure

Abstract

The use of methimazole for the treatment of hyperthyroidism in the first trimester of pregnancy has been linked to several congenital malformations. Most commonly reported is choanal atresia; however, other anomalies have been described including aplasia cutis, esophageal atresia, omphalomesenteric duct remnant, and omphalocele. A definitive phenotype of methimazole embryopathy has not been described. We report a case of a newborn with prenatal methimazole exposure who was found to have an H type tracheoesophageal (TE) fistula, vitelline fistula, ruptured omphalocele, as well as multiple duplication cysts of the stomach and small intestine.