Background <p>Hemoperitoneum, a well-documented manifestation of various gynecological conditions, is herein presented in the first documented case secondary to retained products of conception (RPOC) following a medical abortion. This condition can pose significant diagnostic challenges and carry a high risk of misdiagnosis.</p> Case presentation <p>A 33-year-old woman presented with acute-onset heavy vaginal bleeding and mild lower abdominal pain 33 days after a first-trimester medical abortion (mifepristone and misoprostol). Transvaginal ultrasonography (TVS) revealed an intrauterine mass and significant hemoperitoneum. Emergency dilation and curettage was performed, and histological examination confirmed RPOC with degenerated gestational villi.</p> Conclusion <p>This case highlights an unusual but critical mechanism of hemoperitoneum—retrograde transtubal bleeding from RPOC—expanding the differential diagnosis of hemoperitoneum in women of reproductive age.</p>