Deformed uterus. Coloured 3-D ultrasound scan of the uterus of a patient with a mild deformity called arcuate uterus. The uterus lumen is the Y- shaped region at centre, surrounded by the endometrial lining (dark). In an arcuate uterus, the fundus (across top) is depressed, thus beginning to divide the uterus into two horns. Arcuate uterus is considered a mild form of uterus bicornis. Ultrasound is a diagnostic technique that sends high frequency sound waves into the body via a transducer. The returning echoes are recorded and used to build an image of an internal structure. 3-D ultrasound uses computer technology to return more detailed images than conventional 2-D scans.