Uterine Malformation - Types

Types

The American Fertility Society (now American Society of Reproductive Medicine) Classification distinguishes:

• Class I: Müllerian agenesis (absent uterus).
  • Uterus is not present, vagina only rudimentary or absent. The condition is also called Mayer-Rokitansky-Kuster-Hauser syndrome. The patient with MRKH syndrome will have primary amenorrhea.
• Class II: Unicornuate uterus (a one-sided uterus).
  • Only one side of the Müllerian duct forms. The uterus has a typical "penis shape" on imaging systems.
• Class III: Uterus didelphys, also uterus didelphis (double uterus).
  • 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 (v.i.), or the lower Müllerian system fused into its unpaired condition. See Triplet-birth with Uterus didelphys for a case of a woman having spontaneous birth in both wombs with twins.
• Class IV: Bicornuate uterus (uterus with two horns).
  • 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 (uterine septum or partition).
  • 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.

A uterine septum can be corrected by hysteroscopic surgery.

• Class VI: DES uterus.
  • The uterine cavity has a "T-shape" as a result of fetal exposure to diethylstilbestrol.

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 an unicornuate uterus.

Patients with uterine abnormalities may have associated renal abnormalities including unilateral renal agenesis.