Ultrasound and MRI features are consistent with a partial septate / subseptate uterus and incidental subserosal fibroid. A partial septate uterus involves the endometrial canal but not the cervix, with the angle between the endometrial horns less than 90° and the fundal myometrial depth >1 cm and <1.5 cm. Differential diagnosis is arcuate uterus and bicornuate uterus.