IS Case 115: Septate Uterus
Imaging Sciences URMC 2008
Publication Date: 2009-05-20
The uterine cavity has a broad muscular septum extending from fundus toward the cervix. The septum is incomplete, ending superior to the cervix, and lacks a fibrous component. The serosal surface of the uterine fundus is minimally indented, about 1 mm.
Septate uterus is the most common Müllerian duct anomaly, accounting for 55% of all MDA's. SU results from incomplete resorption of the medial uterovaginal septum during development. Characteristics include a normal convex or minimally (<1 cm) indented external uterine fundal contour. The septum is midline and may be complete, extending to and involving the cervix and even the upper vaginal vault, or incomplete, as in our case, terminating above the cervix. The superior portion of the septum is typically composed of myometrium, with the inferior portion, if present, composed of fibrous tissue. The uterus is generally normal in size.
Hysterosalpingographic findings include a bicompartmental uterine cavity with an angle < 75 degrees between the two chambers. An intercornual distance < 4.0 cm also suggests SU. These two findings are useful in differentiation from bicornuate uterus, which typically has an angle > 105 degrees between the two endometrial compartments and a greater intercornual distance.
Division of the endometrial cavity into two small compartments leads to increased incidence of spontaneous abortions due to uterine insufficiency. Spontaneous abortion rates are as high as 65% of pregnancies. The length of the septum does not correlate with reproductive outcome.
The role of MR imaging in the diagnosis and work-up of SU is mainly differentiation from bicornuate uterus. SU is treated with hysteroscopic resection of the septum, while bicornuate uterus is treated with open metroplasty. After successful hysteroscopic treatment (residual septum less than 1 cm long), the spontaneous abortion rate decreases to 6% of pregnancies, and 85% of pregnancies go on to successful delivery.
- Pellerito JS, McCarthy SM, Doyle MB, Glickman MG, DeCherney AH. Diagnosis of uterine anomalies: relative accuracy of MR imaging, endovaginal sonography, and hysterosalpingography. Radiology. 1992 Jun;183(3):795-800. [PMID: 1584936]
- Carrington BM, Hricak H, Nuruddin RN, Secaf E, Laros RK Jr, Hill EC. Müllerian duct anomalies: MR imaging evaluation. Radiology. 1990 Sep;176(3):715-20. [PMID: 2202012]