Chronic Ectopic Pregnancy Presenting as a Complex Adnexal Mass With Negative Beta-Human Chorionic Gonadotropin Mimicking Ovarian Malignancy: A Case Report

Chronic ectopic pregnancy (CEP) is an uncommon form of ectopic gestation characterized by a slow clinical course and nonspecific symptoms, frequently resulting in delayed or challenging diagnosis. We report the case of a 29‑year‑old woman who presented with persistent lower abdominal pain and intermittent vaginal bleeding for one month, beginning two months after a suspected spontaneous miscarriage. Physical examination revealed a left adnexal mass. Laboratory investigations demonstrated negative serum beta‑human chorionic gonadotropin (β‑hCG) and a normal cancer antigen 125 (CA‑125) level. Pelvic magnetic resonance imaging (MRI) identified a 9.8 cm complex hemorrhagic adnexal mass without post‑contrast enhancement or solid components suggestive of malignancy. Because of progressive hemoglobin decline and persistent diagnostic uncertainty, the patient underwent exploratory laparotomy. Intraoperatively, an organized hematocele with dense adhesions involving the left adnexa was identified, and a left salpingo‑oophorectomy was performed. Histopathology demonstrated chorionic villi and trophoblastic remnants within organized hemorrhagic tissue, confirming CEP. The postoperative course was uneventful, and the patient remained asymptomatic at six‑month follow‑up. This case highlights that CEP may mimic ovarian malignancy despite negative serum β‑hCG and nonspecific imaging findings. Clinicians should maintain CEP within the differential diagnosis when evaluating complex hemorrhagic adnexal masses in reproductive-aged women, even when serum β-hCG is negative, to facilitate timely diagnosis and appropriate surgical management.