Spontaneous ovarian hyperstimulation syndrome: Report of two cases

BACKGROUND: Spontaneous ovarian hyperstimulation syndrome (sOHSS) is extremely rare. It can be divided into four types according to its clinical manifestations and follicle stimulating hormone receptor mutations. CASE SUMMARY: Here we report two cases of sOHSS in Chinese women, one with a singleton gestation developing sOHSS in the first trimester who conceived naturally and the other with a twin pregnancy developing sOHSS in the second trimester after a thawed embryo transfer cycle. Both patients were admitted to the hospital with abdominal distension, ascites, and enlarged ovaries. Conservative treatment was the primary option of management. The first patient had spontaneous onset labor at 40 wk of gestation and underwent an uncomplicated vaginal delivery of a male newborn. The second patient delivered a female baby and a male baby by caesarean section at 35 wk and 1 d of gestation. CONCLUSION: Patients with a history of ovarian hyperstimulation syndrome should be closely monitored. Single embryo transfer might reduce the risk of this rare syndrome.