FREQUENCY: estimated to occur in 1 in 3000 women
PATIENT HISTORY: This uterus was removed from a 26 year old woman who presented with primary amenorrhoea.
The uterus shows two completely separate horns, each measuring 7cm in length, and at their lower ends there appear to be two cervices. The ovaries show multiple small follicular cysts and a few small corpora lutea. The fallopian tubes appear normal.
In uterus didelphys the uterus is a paired organ, ending in two fused cervices. The anomaly is also known as uterus bicornis bicollis. It is often associated with a double vagina. Each hemi-uterus is attached to a fallopian tube.
Pre-pubertal patients are often asymptomatic . After the onset of menstruation, patients may describe the failure a tampon to stop menstrual flow. One hemivagina may be obstructed and intra-uterine bleeding will result in pain and a pelvic mass . An important consequence of and pointer to uterus didelphys is poor obstetric outcome. Recurrent mid-term abortions, malpresentations and premature labour are very common so that only about 70% of pregnancies result in live births. These difficulties are thought to be due to reduced uterine volume and decreased perfusion of the hemi-uterus. (Occasionally patients may have simultaneous pregnancies of different gestations in each hemi-uterus, complicating their management even further.)
Diagnosis of uterus didelphys can be confirmed on ultrasonography, hysteroscopy or MRI. It is important for patients to be investigated for associated renal abnormalities such as a hypoplastic kidney or renal agenesis.
The female genital tract arises from two embryological elements, the Müllerian ducts and the urogenital sinus. The Müllerian ducts differentiate to form the fallopian tubes, body of the uterus, cervix and upper part of the vagina. The urogenital sinus gives rise to the mid and lower part of the vagina. If the process of differentiation, migration, fusion and canalization is interrupted or dysregulated, a wide spectrum of "Müllerian duct anomalies" can result. Uterus didelphys is due to failure of midline fusion of the Müllerian ducts to form a single uterus body and cervix. Septate uterus may be difficult to distinguish from uterus didelphys, but this anomaly arises due to failure of a different embryological process, which is the resorption of the intervening septum after the Müllerian ducts have fused.
The cause of most Müllerian duct anomalies is unknown and probably multifactorial.
PREVENTION & TREATMENT:
In cases of uterus didelphys where there is hemi-vaginal obstruction, surgical correction of the septate vagina is indicated. Reconstructive surgery to unify the uterus (metroplasty) is controversial and seldom performed, but may benefit selected patients who have been unable to carry a pregnancy. (Unlike uterus didelphys, a septate uterus can be relatively easily corrected via hysteroscopy).
Many obstetricians opt for caesarean section delivery in women with didelphys uterus.
MRI of didelphys uterus. (a) Two vaginas and 2 cervices; (b) 2 distinct cervices; (c) 2 uterine horns are widely splayed; (d) cross section of uterine bodies and cervices. http://emedicine.medscape.com/article/405335-imaging