Cesarean scar pregnancy mimicking a pseudo-gestational sac: A case report with magnetic resonance imaging findings

Introduction: A corpus luteal cyst may reportedly be misidentified as an ectopic gestational sac. We report a case of cesarean scar pregnancy mimicking a pseudo-gestational sac, to differentiate between the two entities and diagnose correctly. Case Report: A 42-year-old woman with four previous cesarean sections, at 7 weeks of gestation, was suspected of an unknown site pregnancy. Transvaginal Doppler ultrasonography showed a small cystic structure accompanied by neither a yolk sac nor surrounding marginal flow, adjacent to the uterine scar, and a 16-mm-large low-echo area with a white ring in the left adnexa. Pelvic magnetic resonance imaging also demonstrated a small cystic structure without contrast enhancement resembling a pseudo-gestational sac adjacent to the cesarean scar. Moreover, a cystic structure with ring-enhancement beside the left ovary, which mimicked an ectopic gestational sac, was also detected. Given these imaging findings and slightly elevated serum β-human chorionic gonadotropin (β-hCG) levels, ectopic pregnancy in the left fallopian tube could not be ruled out. She underwent laparoscopic surgery and uterine content removal, which resulted in intrauterine miscarriage. The cystic structure partially resected from a marginal area in the ovary appeared to be a luteal cyst. Conclusion: For correct diagnosis and appropriate treatment, the clinical circumstances should be fully considered without excessive reliance on imaging findings.