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