What is the ESHRE (European Society of Human Reproduction and Embryology) classification of Mullerian anomalies?

ESHRE Classification of Müllerian Anomalies

The ESHRE/ESGE classification system categorizes female genital tract congenital anomalies into six main uterine classes (U0-U6), with independent sub-classifications for cervical and vaginal anomalies based on anatomical deviations with clinical significance. 1, 2

Main Uterine Classes

• U0: Normal uterus - Normal uterine anatomy with straight or curved interostial line and internal indentation at fundal midline not exceeding 50% of the uterine wall thickness 1, 2

• U1: Dysmorphic uterus - Abnormal uterine shape but with normal outline. Includes:

  • U1a: T-shaped uterus (formerly DES-related)
  • U1b: Infantilis uterus
  • U1c: Others 1, 2

• U2: Septate uterus - Normal external uterine contour but abnormal cavity shape due to midline septum. Includes:

  • U2a: Partial septate (septum partially divides cavity above internal os)
  • U2b: Complete septate (septum fully divides cavity to internal os) 1, 2

• U3: Bicorporeal uterus - External indentation at fundal midline >50% of uterine wall thickness. Includes:

  • U3a: Partial bicorporeal (external division partially separates uterine bodies)
  • U3b: Complete bicorporeal (external division fully separates uterine bodies)
  • U3c: Bicorporeal septate (combination of external division and internal septum) 1, 2

• U4: Hemi-uterus - Unilateral formed uterus with contralateral part incompletely formed or absent. Includes:

  • U4a: Hemi-uterus with rudimentary cavity (communicating or non-communicating)
  • U4b: Hemi-uterus without rudimentary cavity 1, 2

• U5: Aplastic uterus - Uterine cavity absent due to complete or partial absence of uterine development. Includes:

  • U5a: Rudimentary horn with cavity (communicating or non-communicating)
  • U5b: Rudimentary horn without cavity/no horn 1, 2

• U6: Unclassified malformations - Rare anomalies that cannot be classified into other categories 1, 2

Cervical Anomalies (C)

• C0: Normal cervix - Normal cervical anatomy 1, 2
• C1: Septate cervix - Cervix divided by septum 1, 2
• C2: Double cervix - Two distinct and separate cervices 1, 2
• C3: Unilateral cervical aplasia - Unilateral cervical formation 1, 2
• C4: Cervical aplasia - Complete cervical absence 1, 2

Vaginal Anomalies (V)

• V0: Normal vagina - Normal vaginal anatomy 1, 2
• V1: Longitudinal non-obstructing vaginal septum - Septum dividing vagina without causing obstruction 1, 2
• V2: Longitudinal obstructing vaginal septum - Septum dividing vagina and causing obstruction 1, 2
• V3: Transverse vaginal septum and/or imperforate hymen - Horizontal septum or imperforate hymen 1, 2
• V4: Vaginal aplasia - Complete or partial absence of vagina 1, 2

Clinical Significance and Diagnostic Methods

• Three-dimensional ultrasound and MRI are the most accurate non-invasive methods for diagnosing Müllerian anomalies, with MRI showing 100% accuracy compared to 92% for 2D transvaginal ultrasound 3

• On both transvaginal ultrasound and MRI, an external fundal cleft >1 cm can be used to diagnose a bicornuate uterus and differentiate it from a septate uterus (fundal cleft <1 cm) 3

• Müllerian anomalies are found in approximately 5% of the general population, with higher prevalence in women with infertility (8.0%), recurrent pregnancy loss (13.3%), and both conditions combined (24.5%) 4

• Accurate classification is essential for appropriate clinical management, as different anomalies have varying impacts on reproductive outcomes and may require different surgical approaches 1, 5

Advantages of the ESHRE/ESGE Classification

• Based on anatomy rather than embryological origin, making it more clinically relevant 1, 2
• Independent classification of uterine, cervical, and vaginal anomalies allows for more precise description of complex malformations 1, 2
• Developed through extensive expert consensus with participation of approximately 90 specialists 1, 2
• Designed to correlate with clinical management decisions and reproductive outcomes 1, 2

This classification system represents a significant improvement over previous systems and provides a standardized framework for diagnosis, research, and treatment planning for women with Müllerian anomalies 1, 2.