Abnormal uterus morphology Unicornuate uterus 2018-06-23T13:42:08Z A uterus that has a single horn, with a banana-like shape that may or may not have a secondary rudimentary uterine horn. A unicornuate uterus with a rudimentary horn is an anomaly caused by defective fusion of one of the paired Mullerian ducts. The incidence of rudimentary-horn pregnancy is estimated to be one in 76,000 pregnancies. Life-threateningly heavy bleeding and abortion are the anticipated outcomes of rudimentary horn pregnancies. According to the literature, the newborn survival rate is between 0-13 percent in pregnancies in the rudimentary horn, with only one third of such gestations reaching term or beyond. Slightly more than half of the pregnancies ended with a rupture of the pregnant uterine horn.