History: 18 year old female with pelvic pain.
On further imaging evaluation with ultrasound, the fluid filled structures in the pelvis turned out to be the right horn of a uterine didelphys and the right portion of the vagina, which was obstructed by a transverse septum. Look again at the image above. The left horn of the uterus can be seen as the isointense round structure in the left hemipelvis.
The diagnosis in this case is hematometrocolpos. This can be due to a transverse vaginal septum in cases of Mullerian duct anomalies, or to an imperforate hymen in young females. It typically becomes symptomatic shortly after menarche as blood products begin to expand the uterus and vagina and cause pain.