Clinical characteristics of mirror syndrome: a comparison of 10 cases of mirror syndrome with non-mirror syndrome fetal hydrops cases

Objective: To investigate clinical features of mirror syndrome. Methods: We retrospectively reviewed 71 cases of fetal hydrops with or without mirror syndrome, and compared with respect to maternal age, the body mass index, the primipara rate, the gestational age at delivery, the timing of fetal hydrops onset, the severity of fetal edema, placental swelling, the laboratory data and the fetal mortality. The data are expressed as the medians. Results: Mirror syndrome developed in 29% (10/35) of the cases with fetal hydrops. In mirror group, the onset time of fetal hydrops was significantly earlier (29 weeks versus 31 weeks, p = 0.011), and the severity of fetal hydrops (fetal edema/biparietal diameter) was significantly higher than non-mirror group (0.23 versus 0.16, p<0.001). There was significantly higher serum human chorionic gonadotropin (hCG) (453000 IU/L versus 80000 IU/L, p<0.001) and lower hemoglobin (8.9 g/dL versus 10.1 g/dL, p = 0.002), hypoalbuminemia (2.3 mg/dL versus 2.7 mg/dL, p = 0.007), hyperuricemia (6.4 mg/dL versus 5.0 mg/dL, p = 0.043) in mirror group. Conclusion: Mirror syndrome is occurred frequently in early and severe fetal hydrops and cause hemodilution and elevation of serum hCG.