Mirroring pre-eclampsia: Ballantyne's under the microscope.

Background Mirror syndrome (Ballantyne's syndrome) is a rare condition recognised in the context of non-immune and immune fetal hydrops with the presence of 'triple oedema' - a hydropic fetus, alongside marked maternal and placental oedema - hallmarking the maternal-fetal mirror. The mother may also develop proteinuria and hypertension, thereby simulating a clinical picture of preeclampsia; however, unlike pre-eclampsia, mirror syndrome is characterised by maternal haemodilution alongside fetal hydrops and polyhydramnios. The exact pathophysiology of mirror syndrome is not known, however that of pre-eclampsia is widely acknowledged to have genesis in abnormal placentation leading to hypoxia, placental oxidative stress and release of factors causing endothelial activation and vasoconstriction. Frequently implicated factors in this pathway include angiogenic factors such as the VEGF receptor sFlt, activin and follistatin, along with 8-isoprostane, endothelin-1 (ET-1), intercellular adhesion molecule-1 (ICAM-1) and von Willebrand factor (vWF). Since mirror syndrome resembles a 'preeclampsia phenotype', we test the hypothesis that its clinical features are mediated by the same circulating factors as those in preeclampsia. Case We report the case of a 29 year-old at 26 + 2 weeks that underwent successful fetoscopic laser photocoagulation for Stage IV TTTS. Between days 4-5 post-procedure, the patient became increasingly hypertensive and proteinuric. Follow-up ultrasound was performed paradoxically showing new-onset ascites in the donor twin. On day 7, the patient became increasingly tachycardic, dyspnoeic and hypoxic. Blood indices showed: Hb 7.8 g/dL, Hct 0.22 L/L, albumin 16, CRP 56 and pO2 64 mmHg on room air. Chest X-ray confirmed pulmonary oedema. A diagnosis of mirror syndrome was made and the twins delivered by caesarean. Placental histopathology showed oedematous villi confined to the donor twin territory, pathognomonic of mirror syndrome. Concurrent to the clini