A rare case of a retroperitoneal pregnancy: case report.

A 21-year-old parous woman (G2, P1) presented with sudden abdominal pain in a state of hemodynamic shock. Despite 10 weeks of amenorrhea and a serum β-human chorionic gonadotropin (β-HCG) level >10 000 U/l, several ultrasound (US) scans in another facility failed to detect intrauterine pregnancy. Her history includes past motor vehicle accident. During emergency laparotomy, a moderate amount of hemoperitoneum was seen with a normal uterus and adnexa. A right-sided pelvic wall hematoma was noted. Abdominal US and computed tomography scans demonstrated a large retroperitoneal hematoma with active bleeding. The hematoma spanned from the liver to the pelvic brim with a central cyst-like structure that resembled a gestational sac. During an upper midline laparotomy performed by a multidisciplinary team, the hematoma was evacuated. Histopathological examination of structures within the clot identified chorionic villi. The patient underwent blood transfusions and recovered uneventfully under proper antibiotic prophylaxis. β-HCG levels dropped to zero within 2 weeks.