Uterus didelphys

Uterus didelphys (sometimes also uterus didelphis) represents a uterine malformation where the uterus is present as a paired organ as the embryogenetic fusion of the mullerian ducts failed to occur. As a result there is a double uterus. Each uterus has a single horn linked to the ipsilateral fallopian tube that faces its ovary.

Etiology
The uterus is formed during embryogenesis by the fusion of the two mullerian ducts. This process usually fuses the two mullerian ducts into a single uterine body but fails to take place in these affected women who maintain their double mullerian systems. A didelphic uterus will have a double cervix and is usually associated with a double vagina. Causes for the failure to fuse are not known. Associated defects may affect the vagina, the renal system, and less common, the skeleton.

The condition is less common than these other uterine malformations: arcuate uterus, septate uterus, and bicornuate uterus. It has been estimated to occur in 1/3,000 women.

Presentation
Women with the condition may be asymptomatic and unaware of having a double uterus. However, a study by Heinonen showed that certain conditions are more common. In his study of 26 women with a double uterus gynecological complaints included dysmenorrhea and dyspareunia. All patients displayed a double vagina. The fetal survival rate in 18 patients who delivered was 67.5%. Breech presentation was present in 43% and premature delivery common (21%).

Diagnosis
A pelvic examination will typically reveal a double vagina and a double cervix. Investigations are usually prompted on the basis of such findings as well as when reproductive problems are encountered.

Helpful techniques to investigate the uterine structure are transvaginal ultrasonography and sonohysterography, hysterosalpingography, MRI, and hysteroscopy. More recently 3-D ultrasonography has been advocated as an excellent non-invasive method to evaluate uterine malformations.

Management
Patients with an double uterus may need special attention during pregnancy as premature birth and malpresentation are common. Cesarean section was preformed in 82% of patients reported by Heinonen.

Syndrome
A specific association of uterus didelphys, unilateral hematocolpos and ispilateral renal agenesis has been described.

Multiple pregnancy
A number of twin gestations have occurred where each uterus carried its pregnancy separately. It is possible that the delivery occurs at different time, thus the delivery interval could be days or even weeks.

Triplets
A UK woman with a double uterus gave birth to triplets in 2006. Hannah Kersey, of Northam in Devon, gave birth to a pair of identical twins from an egg that implanted into one womb and then divided, and to an infant from a single egg that implanted into the other womb. This was the first known birth of viable triplets in a woman with a double uterus. . It is estimated that the possibility of such a birth is about 1 in 25 million. A triplet pregnancy in a woman with uterus didelphys was reported from Israel in 1981; one baby died in utero, and of the remaining babies, one was delivered at 27 weeks gestation and the other 72 days later.