Unicornuate uterus with left fallopian tube
Müllerian duct anomalies are an uncommon but often treatable cause of infertility.
The role of imaging is to help detect, diagnose, and distinguish surgically correctable forms of müllerian duct anomalies from inoperable forms.
EMBRYOLOGY—
Complete formation and differentiation of the müllerian ducts into the segments of the female reproductive tract depend on completion of 3 phases of development as follows.
1) Organogenesis-
2) Fusion: The process during which the lower segments of the paired müllerian ducts fuse to form the uterus, cervix, and upper vagina is termed lateral fusion.
3) Septal resorption: After the lower müllerian ducts fuse, a central septum is present, which subsequently must be resorbed to form a single uterine cavity and cervix.
Müllerian duct anomalies are categorized most commonly into 7 classes according to the American Fertility Society (AFS) Classification Scheme as follows:
- Class I (hypoplasia/agenesis): This class includes entities such as uterine/cervical agenesis or hypoplasia. The most common form is the Mayer-Rokitansky-Kuster-Hauser syndrome,.
- Class II (unicornuate uterus): A unicornuate uterus is the result of complete, or almost complete, arrest of development of 1 müllerian duct.
- Class III (didelphys uterus): This anomaly results from complete nonfusion of both müllerian ducts. Didelphys uteri have the highest association with transverse vaginal septa, Consider metroplasty; however, since each horn is almost a fully developed uterus, patients have been known to carry pregnancies to full term.
- Class IV (bicornuate uterus): A bicornuate uterus results from partial nonfusion of the müllerian ducts .
- Class V (septate uterus): A septate uterus results from failure of resorption of the septum between the 2 uterine horns. The septum can be partial or complete, in which case it extends to the internal cervical os.
- Class VI (arcuate uterus): An arcuate uterus has a single uterine cavity with a convex or flat uterine fundus, the endometrial cavity, which demonstrates a small fundal cleft or impression (³1.5 cm).
- Class VII (diethylstilbestrol-related anomaly): uterine hypoplasia and a T-shaped uterine cavity. Patients also may have abnormal transverse ridges, hoods, stenoses of the cervix, and adenosis of the vagina with increased risk of vaginal clear cell carcinoma.
DIAGNOSIS-
HSG--.Typically, the question of müllerian duct anomaly arises during HSG examination if the typical trigone configuration of the cavity is not demonstrated. A common finding is separation of the uterine cavity into right and left compartments. Certain criteria are used to increase confidence in diagnosing 1 of the 3 entities.
1) Intercornual distance: If the distance between the distal ends of the horns (ends that are continuous with fallopian tubes) is less than 2 cm, the likelihood of septate uterus is increased. If the distance is greater than 4 cm, the likelihood of didelphys uterus is increased.
2) Intercornual angle: This is the angle formed by the most medial aspects of the 2 uterine hemicavities. If the angle is less than 60°, septate uterus is more likely).
3) T-shaped cavity: A hypoplastic, irregular, T-shaped uterine cavity is pathognomonic for in utero DES exposure