Twin reverse arterial perfusion sequence.

Twin reverse arterial perfusion sequence occurs in approximately one percent of monochorionic twins. This condition is always fatal for the recipient twin and carries a high mortality rate for the pump twin. Various treatment options are described, but management is continually evolving with the publication of new data. We report an acardiac acephalic monochorionic twin who was diagnosed at 31 weeks gestation. Serial ultrasonographical examinations of the normal pump twin showed intrauterine growth restriction but with no evidence of heart failure. A healthy pump twin was delivered by caesarean section at 34 weeks.