Significance of Donor Anuria Differs between Monoamniotic and Diamniotic Twin–Twin Transfusion Syndrome

Development of severe twin–twin transfusion syndrome (TTTS) in diamniotic–monochorionic twins includes five stages of increasing severity, i.e. recipient polyhydramnios and donor oligohydramnios, donor anuria, abnormal umbilical flow velocities in either twin, hydrops in the recipient, and intrauterine fetal death (IUFD) in either or both twins. In a severe case of TTTS in monoamniotic twins we observed donor anuria to appear after hydrops in the recipient. We conclude that donor anuria is a late and serious symptom in monoamniotic TTTS.