Rudimentary horn pregnancy mimicking tubal ectopic pregnancy: a diagnostic dilemma

Rudimentary horn pregnancy is a rare form of ectopic pregnancy associated with Müllerian duct anomalies and carries a high risk of uterine rupture and life-threatening haemorrhage. We report the case of a woman in her 20s, gravida 2, abortion 1, who presented with 6 weeks of amenorrhoea and a positive urine pregnancy test. Transvaginal ultrasonography demonstrated a 6-week 4-day gestational sac in the right adnexa with an empty uterine cavity, suggestive of an ectopic pregnancy. Diagnostic laparoscopy revealed a right rudimentary horn pregnancy, which was excised along with the ipsilateral fallopian tube. The postoperative course was uneventful, and histopathological examination confirmed gestational tissue within the rudimentary horn. This case highlights the diagnostic challenge of distinguishing rudimentary horn pregnancy from tubal ectopic pregnancy and emphasises the importance of early recognition and timely surgical management to prevent catastrophic rupture and haemorrhage.