Ovarian hyperstimulation syndrome in a frozen-thawed embryo transfer pregnancy: a rare case report

BACKGROUND: Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic complication of ovarian stimulation. Prevention and early recognition of OHSS are important to ensure patient safety. CASE PRESENTATION: In this case, we reported a patient who underwent controlled ovarian hyperstimulation (COH) and in vitro fertilization (IVF). All embryos were cryopreserved to reduce possible OHSS. However, OHSS still occurred after the patient had a frozen-thawed embryo transfer (FET) with hormone replacement therapy (HRT) and obtained a dichorionic diamniotic triplet pregnancy. After multifetal pregnancy reduction (MFPR) and supportive treatment, all the symptoms regressed. CONCLUSIONS: Prompt recognition of OHSS, especially in patients who have no history of ovulation induction and fresh embryo transfer, is very important. Multiple pregnancies may lead to severe OHSS because of the high level of human chorionic gonadotropin (hCG) in the early stages. We suggest that a single embryo transfer may be necessary and beneficial for patients.