*Only one side of the Müllerian duct forms. The uterus has a typical "banana shape" on imaging systems.
Class III: Uterus didelphys, also uterus didelphis.
*Both Müllerian ducts develop but fail to fuse, thus the patient has a "double uterus". This may be a condition with a double cervix and a vaginal partition, or the lower Müllerian system fused into its unpaired condition. See for a case of a woman having spontaneous birth in both wombs with twins.
Class IV: Bicornuate uterus.
*Only the upper part of that part of the Müllerian system that forms the uterus fails to fuse, thus the caudal part of the uterus is normal, the cranial part is bifurcated. The uterus is "heart-shaped".
Class V: Septated uterus.
*The two Müllerian ducts have fused, but the partition between them is still present, splitting the system into two parts. With a complete septum the vagina, cervix and the uterus can be partitioned. Usually the septum affects only the cranial part of the uterus. A uterine septum is the most common uterine malformation and a cause for miscarriages. It is diagnosed by medical image techniques, i.e. ultrasound or an MRI. MRI is considered the preferred modality due to its multiplanar capabilities as well as its ability to evaluate the uterine contour, junctional zone, and other pelvic anatomy. A hysterosalpingogram is not considered as useful due to the inability of the technique to evaluate the exterior contour of the uterus and distinguish between a bicornuate and septate uterus.
An additional variation is the arcuate uterus where there is a concave dimple in the uterine fundus within the cavity. A rudimentary uterus is a uterine remnant not connected to cervix and vagina and may be found on the other side of a unicornuate uterus. Patients with uterine abnormalities may have associated renal abnormalities including unilateral renal agenesis.
Diagnosis
Besides a physical examination, the physician will need imaging techniques to determine the character of the malformation: gynecologic ultrasonography, pelvic MRI, or hysterosalpingography. A hysterosalpingogram is not considered as useful due to the inability of the technique to evaluate the exterior contour of the uterus and distinguish between a bicornuate and septate uterus. In addition, laparoscopy and/or hysteroscopy may be indicated. In some patients the vaginal development may be affected.
Treatment
Surgical intervention depends on the extent of the individual problem. With a didelphic uterus surgery is not usually recommended. A uterine septum can be resected in a simple out-patient procedure that combines laparoscopy and hysteroscopy. This procedure greatly decreases the rate of miscarriage for women with this anomaly.
Prevalence
The prevalence of uterine malformation is estimated to be 6.7% in the general population, slightly higher in the infertility population, and significantly higher in a population of women with a history of recurrent miscarriages.
