Spontaneous Ovarian Hyperstimulation Syndrome in Natural Conception: A Case Report.

Ovarian hyperstimulation syndrome (OHSS) is a serious condition usually associated with assisted reproductive technologies, but spontaneous OHSS occurring in natural pregnancies is a rare and often overlooked entity. We report the case of a 28-year-old woman, gravida 2 para 1, who presented in early pregnancy with progressive abdominal distension, dyspnea, and hemoconcentration without any history of fertility treatment. Imaging revealed bilateral multicystic ovarian enlargement, significant ascites, and small pleural effusions, while laboratory studies confirmed elevated endogenous human chorionic gonadotropin levels. She was diagnosed with moderate-to-severe spontaneous OHSS and was managed conservatively with intravenous fluids, correction of electrolyte imbalances, thromboprophylaxis, and ultrasound-guided therapeutic paracentesis, leading to gradual clinical improvement. The pregnancy remained viable, and the patient was discharged in stable condition with close follow-up. This case highlights the need for heightened clinical suspicion of spontaneous OHSS in early pregnancy, even in the absence of ovulation induction, as early diagnosis and supportive management are critical for optimizing maternal and fetal outcomes.