LAUSR

Background We present a rare case of a dichorionic-diamniotic twin pregnancy in a noncommunicating rudimentary uterine horn diagnosed prior to rupture at 12 weeks of gestation. Case A 33-year-old woman with history of two prior spontaneous abortions presented with a spontaneously conceived dichorionic-diamniotic twin pregnancy. Routine first-trimester screening ultrasound detected an extrauterine twin pregnancy. The patient was admitted for observation and treatment planning. Magnetic resonance imaging (MRI) of the pelvis led to the radiologic diagnosis of suspected abdominal ectopic pregnancy. Exploratory laparotomy led to an intraoperative diagnosis of twin pregnancy within a rudimentary uterine horn, which was removed without incident. Conclusion This is a rare case of a twin pregnancy contained in a noncommunicating rudimentary uterine horn. The presence of this horn was not detected on ultrasonography or MRI.