spontaneous perirenal hemorrhage in a pregnant woman due to the rupture of a simple renal cyst

Renal cysts are diagnosed by ultrasonography, computerized tomography (ct), or urography. a 36-year-old pregnant woman (g2, ab1, within the gestational age of 38 weeks) with upper abdominal pain starting from two hours ago, vomiting, and nausea was referred to the emergency department. although abdominal examinations revealed costovertebral angle tenderness, there were no signs of peritoneal irritation, and all vital signs of the patient were in a normal range. initial investigation results including blood count (hb: 11.4), bun/cr, na/k, and ua were normal. she underwent a cesarean section (c/s) due to reduced fetal heart rate (fhr). after c/s,the ct scan showed a large left retroperitoneal hematoma with an anterosuperior displacement of the kidney and active bleeding in the cystic lesion of the upper pole of the kidney. pathological examinations also confirmed a simple cyst. overall, simple renal cysts should be considered as a rare cause of spontaneous perinatal hemorrhage (sph) in pregnancy. the diagnosis and treatment of sph in pregnancy are also critical challenges.