Exposure to methylergonovine maleate as a cause of sirenomelia

Background Sirenomelia is a rare, but deadly condition characterized by fusion of the lower limbs, lower spinal column defects, severe malformations of the urogenital and lower gastrointestinal tract, and an aberrant abdominal umbilical artery. Methods The two main hypotheses, not mutually exclusive, that have been advanced to explain the pathogenesis of sirenomelia are the blastogenetic theory and the vascular disruption theory. Results We describe a case of sirenomelia, probably associated with the use of methylergonovine maleate, an ergot alkaloid, during the first weeks of pregnancy. Conclusion On the basis of the mechanisms of vascular disruption and early administration of methylergonovine maleate at a critical stage of organogenesis, we conclude that exposure to methylergonovine maleate could be the cause of the development of sirenomelia. Birth Defects Research (Part A) 106:643–647, 2016. © 2016 Wiley Periodicals, Inc.