A common finding is separation of the uterine cavity into right and left compartments. A divided uterine cavity can result from septate, bicornuate, or didelphys uterus. Certain criteria are used to increase confidence in diagnosing 1 of the 3 entities.
- Intercornual distance: If the distance between the distal ends of the horns (ends that are continuous with fallopian tubes) is less than 2 cm, the likelihood of septate uterus is increased. If the distance is greater than 4 cm, the likelihood of didelphys uterus is increased. Measurements of 2-4 cm (typical distance in a normal uterus) were indeterminate in an abnormal cavity configuration.
- Intercornual angle: This is the angle formed by the most medial aspects of the 2 uterine hemicavities. If the angle is less than 60°, septate uterus is more likely. For larger angles, the anomaly is more likely to be a bicornuate uterus.
- T-shaped cavity: A hypoplastic, irregular, T-shaped uterine cavity is pathognomonic for in utero DES exposure. The uterus typically is much smaller than average, and many forms of cavity appearance exist with varying, but usually symmetric, regions of narrowing or dilatation in the segments of the T