Mirror syndrome after fetoscopic laser therapy for twin-twin transfusion syndrome due to transient donor hydrops that resolved before delivery. A case report.

Background: Mirror syndrome is a rare complication of twin-twin transfusion syndrome (TTTS). Its clinical picture includes massive edema, oliguria, and hemodilution in the context of fetal hydrops. The occurrence of mirror syndrome after fetoscopic laser therapy for TTTS has been well documented, but resolution of mirror syndrome before delivery has not been reported in the literature.
Case: A 33-year-old woman was referred to our institution at 23(6)/7 weeks' gestation for TTTS, which had been treated with amnioreduction twice: at 21 and 22 gestational weeks, respectively. Mirror syndrome was diagnosed after fetoscopic laser therapy for TTTS at 24 weeks' gestation due to maternal manifestations of pulmonary edema, skin edema, anemia, low blood protein concentration and proteinuria accompanied by donor hydrops. The maternal respiratory symptoms then gradually abated in <2 weeks along with improved fetal condition, resulting in a delivery with favorable outcomes at 36 weeks' gestation.
Conclusion: Manifestation of mirror syndrome after fetoscopic laser therapy in twin-twin transfusion due to donor hydrops doesn't necessarily predict a poor perinatal outcome.