Uterine malformations (septate, bicornuate uterus)

Definition

• Congenital uterine anomalies result from abnormal formation, canalisation or fusion of the Müllerian ducts or from defective resorption of the midline septum.
• A bicornuate uterus results from incomplete fusion of the Müllerian ducts, typically between weeks 6 and 10, and has two separate endometrial cavities with a single cervix.

Classification

• The ASRM classification (most recently 2021, nine categories) and the 2013 ESHRE/ESGE classification are in use; neither is universally accepted.
• For a septate uterus ASRM 2021 requires an indentation deeper than 1 cm with an angle under 90° and a normal external shape, ESHRE/ESGE an indentation-to-wall-thickness ratio over 50%.

Occurrence & epidemiology

Epidemiology

• Congenital uterine anomalies are found in about 5.5% of unselected women, 8% of infertile women and 13.3% of women with miscarriage.
• The septate uterus accounts for about 35% of anomalies, with a prevalence of 0.2–2.3% in women of reproductive age.

Clinical features

• With a septate uterus, infertility, recurrent miscarriage, preterm birth and fetal malpresentation are more frequent.
• A bicornuate uterus is likewise associated with infertility, recurrent pregnancy loss, preterm labour and malpresentation.

Diagnosis

• Hysteroscopy is the gold standard for the septate uterus; 3D transvaginal ultrasound shows the cavity and the external fundal contour in the coronal plane.
• 3D ultrasound or MRI is used to distinguish a bicornuate from a septate uterus.
• In a meta-analysis the pooled sensitivity and specificity of 2D transvaginal ultrasound for septate uterus were 83% and 99%.

Keep learning in the app

Further reading (selection)

1. Diagnostic Performance of Two-Dimensional Ultrasound, Two-Dimensional Sonohysterography and Three-Dimensional Ultrasound in the Diagnosis of Septate Uterus-A Systematic Review and Meta-Analysis (Diagnostics (Basel) 2023, PubMed Central)
2. StatPearls: Bicornuate Uterus (NCBI Bookshelf)

Cross-references