What is a septate uterus?

Septate Uterus: Definition, Diagnosis, and Clinical Implications

A septate uterus is the most common congenital uterine anomaly, characterized by the presence of a fibromuscular septum that partially or completely divides the uterine cavity. This Müllerian duct anomaly results from incomplete resorption of the midline septum between the two fused müllerian ducts during embryological development. 1, 2

Diagnostic Features

• MRI is the gold standard for diagnosing and classifying septate uterus with 100% accuracy in surgically proven Müllerian duct anomalies 1
• 3D transvaginal ultrasound (TVUS) is an excellent alternative with 92% accuracy in classification of Müllerian duct anomalies 1, 3
• On both TVUS and MRI, a fundal cleft <1 cm indicates septate uterus while a cleft >1 cm suggests bicornuate uterus 1
• A fundal indentation <5 mm above the interostial line helps identify septate versus bicornuate uterus 1
• Hysterosalpingography (HSG) has poor accuracy (only 16.7%) in characterizing Müllerian duct anomalies and cannot reliably differentiate between septate and bicornuate uterus 1
• Three-dimensional US has become particularly useful in improving detection of uterine cavity lesions and classification of congenital uterine anomalies 3

Prevalence and Clinical Significance

• The estimated prevalence of septate uterus ranges from 0.2-2.3% in women of reproductive age 4
• Septate uterus has historically been associated with adverse reproductive outcomes including: 5, 4
  • Increased risk of miscarriage
  • Premature delivery
  • Fetal malpresentation
• When describing gestational sac location in a septate uterus, proper terminology should specify the location relative to the uterine Müllerian duct anomaly (e.g., "GS in right horn of septate uterus") 3

Treatment Considerations

• Recent high-quality evidence challenges the traditional belief that septum resection improves reproductive outcomes 6, 4
• A 2021 randomized controlled trial found that hysteroscopic septum resection did not improve live birth rates compared to expectant management (31% vs 35%) 6
• A large cohort study similarly showed no improvement in live birth rates with septum resection (53.0%) compared to expectant management (71.7%) 4
• Septum resection also did not significantly reduce rates of pregnancy loss or preterm birth compared to expectant management 4

Surgical Approach

• If septum resection is considered, hysteroscopic metroplasty has replaced traditional transabdominal approaches due to: 7
  • Lower morbidity
  • Avoidance of hysterotomy complications like adnexal adhesions
  • Shorter recovery time
• Laparoscopy may be used in conjunction with hysteroscopy to aid in diagnosis and enhance the safety and efficiency of the procedure 2

Clinical Pitfalls and Considerations

• Avoid using terms like "unicornuate pregnancy" or "bicornuate pregnancy" when describing gestational sacs in septate uteri; instead describe the GS location relative to the uterine Müllerian duct anomaly 3
• The definition of septate uterus has evolved over time with different classification systems, which may affect diagnostic consistency across studies 4
• Careful differential diagnosis is needed to distinguish septate uterus from other Müllerian anomalies, particularly bicornuate uterus 1
• Current evidence suggests that septum resection, despite being widely offered, may not lead to improved reproductive outcomes compared to expectant management 6, 4