A 32-year-old woman of child-bearing age who initially underwent surgical laparoscopy for suspected ruptured ectopic pregnancy with elevated serum β-human chorionic gonadotropin (hCG) levels was unexpectedly found to have histologically diagnosed synchronous ovarian and endometrial endometrioid adenocarcinoma. She subsequently underwent another full completion staging surgery and adjuvant chemotherapy as she was unsuitable for fertility-sparing surgery. An elevated serum β-hCG level accompanied by clinical signs of acute abdominal pain, per vaginal bleeding, ultrasound features of abdominal free fluid in the pelvis and an adnexal mass warrants a high clinical suspicion for a ruptured ectopic pregnancy. However, it is important to recognize ovarian malignancy as a rare but differential diagnosis to suspected ectopic pregnancy in patients with acute abdomen. Fertility-sparing surgery may be considered for young patients seeking fertility, without compromising patient survival in women without synchronous gynecological cancers.