Bicornuate uterus

A bicornuate uterus is a type of uterine duplication anomaly. It can be classified as a class IV Mullerian duct anomaly.

Epidemiology

Overall, congenital uterine anomalies occur in ~1.5% of females (range 0.1-3%). Bicornuate uteri are thought to represent ~25% (range 10-39%) of Mullerian duct anomalies 6,9.

Clinical presentation

In most cases, a bicornuate uterus is incidentally discovered when the pelvis is imaged. The most common symptomatic presentation is with early pregnancy loss and cervical incompetence 6 . Infertility is not usually a problem with this type of malformation because implantation of the embryo is not impaired. 

Pathology

A bicornuate uterus results from an abnormal development of the paramesonephric ducts. There is a partial failure of fusion of the ducts, resulting in a uterus divided into two horns.

Associations
  • associated longitudinal vaginal septum may be present in ~25% of cases
  • as with other Mullerian duct anomalies, abnormalities of the renal tract may also be present
Subtypes

Bicornuate uterus is divided according to the involvement of the cervical canal:

Radiographic features

General

The preferred methods of imaging uterine anomalies are ultrasound, hysterosalpingogram or MRI. The external uterine contour is concave or heart-shaped, and the uterine horns are widely divergent. The fundal cleft is typically more than 1cm deep and the intercornual distance is widened.

The uterus is seen as comprising of caudally fused symmetric uterine cavities with some degree of communication between the two cavities (usually at the uterine isthmus). Although not a specific finding, the angle between the horns of the bicornuate uterus is usually more than 105° 3

Fluoroscopy: hysterosalpingogram (HSG)

A divided uterus can be seen, but it is difficult to differentiate between septate and bicornuate anomalies since the uterine fundal contour is not visible 5.

MRI

May help confirm anatomy by showing a deep (>1 cm) fundal cleft in the outer uterine contour and an intercornual distance of >4 cm. The uterus demonstrates normal uterine zonal anatomy

Treatment and prognosis

Surgical intervention is usually not indicated in absence of reproductive difficulties. 

In women with a history of recurrent pregnancy loss and in whom no other infertility issues have been identified a Strassman metroplasty can be considered. 

In patients with cervical incompetence placement of a cervical cerclage may increase fetal survival rates 9. Indeed the association between cervical incompetence and bicornuate uterus is so high, that prophylactic cerclage may be appropriate in some instances. 

Practical points

Septate uterus increases the risk of early pregnancy loss and hysteroscopic intervention to resect the septum is sometimes pursued. In this situation, differentiation between a septate uterus or a bicornuate uterus is critical. This is mostly a problem with HSG preoperative evaluation. Attempted resection of a bicornuate uterus "septum" leads to a poor outcome.

See also

  • uterus didelphys: complete failure of fusion occurs during development of the paramesonephric ducts with duplication of the uterus, cervix and vagina
  • septate uterus 12: has a normal fundal contour but is characterised by a persistent longitudinal septum that partially divides the uterine cavity

Abdominal and pelvic anatomy
Ultrasound - general index
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Article Information

rID: 989
System: Gynaecology
Section: Anatomy
Synonyms or Alternate Spellings:
  • Bicornuate uteri
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    Bicornuate unicol...
    Figure 1: illustration - bicornuate unicollis uterus
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    Case 1
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    Bicornuate bicoll...
    Figure 2: illustration - bicornuate bicollis
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    Bicornuate uterus
    Case 2
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    Bicornuate uterus...
    Figure 3: gross pathology
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    Axial T2 pelvis

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    Case 3
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    Bicornuate Uterus
    Case 4: with solitary kidney
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    Case 5
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    Bicornuate pregna...
    Case 6: with pregnancy in one horn
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    Case 7
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    Case 8
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    Case 9: with concurrent appendicitis
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    Case 10
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    Case 11
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    Case 12
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    Case 13
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    Case 14
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    Case 15: on HSG
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