Ruptured rudimentary horn pregnancy with a history of an uneventful vaginal delivery

Pregnancy in a rudimentary uterine horn is a rare event with an estimated incidence of 1 in 76,000 to 1 in 1,40,000 pregnancies. Unicornuate uterus with a rudimentary horn has a high incidence of obstetric and gynecological complications. Ruptured ectopic pregnancy in the rudimentary horn is one of the most dreaded complications, which can have grave consequences for both mother and fetus. In the majority of the cases, it is detected after rupture of the horn, usually during the first or second trimester of pregnancy. An ultrasonographic diagnosis made prior to rupture of the rudimentary horn may prevent this catastrophic outcome. We report a case of a G2 P1 L1 with a ruptured left rudimentary horn pregnancy at 16 weeks of gestation that was misdiagnosed as a pregnancy in the left uterine horn of a bicornuate uterus on prior prenatal ultrasound. The patient presented to our hospital with abdominal pain and vaginal bleeding. A diagnosis of ruptured left rudimentary horn pregnancy was made on the basis of emergency ultrasound and was later confirmed on laparotomy. The left rudimentary horn along with the ipsilateral fallopian tube was excised.