Hemoperitoneum from ruptured cyst in a hyperstimulated ovary: a sonographic mimic of ovarian hyperstimulation syndrome.

We report a case of a ruptured cyst in a hyperstimulated ovary that was initially misinterpreted as ovarian hyperstimulation syndrome (OHSS). A 22-year-old woman who was on oral clomiphene citrate for primary infertility presented with pain in the lower abdomen, hypotension, and tachycardia. Sonographic examination revealed multiple cysts in both ovaries and free fluid in the abdomen, and the initial diagnosis was OHSS. However, sonographically guided aspiration of free fluid revealed a hemoperitoneum, and the patient underwent emergent surgery. At laparotomy, an actively bleeding ruptured cyst in a hyperstimulated ovary was found to be the cause of the hemoperitoneum. Radiologists must be familiar with the imaging features of this condition to avoid misdiagnosing it as OHSS, because this could potentially delay urgently required surgery.