•A 20 years-old nulliparous haemodynamically stable woman presented to the emergency department with acute right lower quadrant abdominal and pelvic pain.

•Pelvic ultrasound showed a live ectopic pregnancy at 6 weeks gestation.

•An emergency diagnostic laparoscopy identified an unruptured ectopic pregnancy in the right rudimentary uterine horn.

•The rudimentary horn was resected, and an ipsilateral salpingectomy was performed.

•The histopathology report confirmed the ectopic pregnancy in the rudimentary uterine horn. 

•There are no clear clinical criteria to identify this life-threatening pregnancy, which makes diagnosis difficult.

•The sensitivity of ultrasound for detecting a rudimentary horn is only 26% and may often remain inconclusive.

•Management depends on the patient's gestational age and hemodynamic stability.

•The first line of management is the removal of the uterine horn to prevent life-threatening rupture of ectopic pregnancy, either by laparoscopy or laparotomy.

•In our case, we resected the rudimentary horn and its fallopian tube by laparoscopy. The patient had an uneventful recovery. 

•Alternatively, medical management with methotrexate could be considered in hemodynamically stable patients with an early gestation.

•Once the pregnancy resolves completely, the patient can undergo surgical management to remove the rudimentary horn and ipsilateral fallopian tube to prevent future ectopic pregnancies. 

•Pregnancies in the rudimentary uterine horn are rare with a high maternal mortality rate due to increased risks of rupture and life-threatening haemorrhage.

• Early diagnosis and surgical management are essential to prevent adverse outcomes.