ASRM Mullerian Anomalies Classification 2021 (MAC2021)

Background & Goals

1. Builds on the 1988 AFS classification - preserves simplicity and recognizability
2. Expands coverage - now includes uterine, cervical, AND vaginal anomalies (1988 version did not include cervical/vaginal)
3. Standardizes terminology across disciplines
4. Incorporates imaging guidance - MRI, 2D/3D ultrasound, HSG, hysteroscopy, laparoscopy
5. Acknowledges overlap - anomalies represent a continuum; cross-referencing between categories is allowed
6. Interactive digital tool available on the ASRM website for education and clinical use
7. Promotes patient advocacy and multidisciplinary awareness

The 9 Categories of MAC2021

1. Mullerian Agenesis

• Mullerian agenesis (MRKH syndrome spectrum)
• Mullerian agenesis with bilateral atrophic uterine remnants with functional endometrium
• Mullerian agenesis with R/L atrophic uterine remnant with functional endometrium

2. Cervical Agenesis

• Cervical agenesis
• Distal cervical agenesis

3. Unicornuate Uterus

• R/L unicornuate uterus (no remnant)
• R/L unicornuate with R/L distal atrophic uterine remnant
• R/L unicornuate with R/L distal uterine remnant with functional endometrium
• R/L unicornuate with R/L associated atrophic uterine remnant
• R/L unicornuate with R/L uterine horn communicating at the level of the cervix

4. Uterus Didelphys

• Uterus didelphys and longitudinal septum
• Uterus didelphys +/- longitudinal vaginal septum of variable length
• Uterine didelphys and obstructed R/L hemivagina (Herlyn-Werner-Wunderlich syndrome)

5. Bicornuate Uterus

• Bicornuate uterus - serosal indentation >1 cm (measured from the bicornual line)
• Bicornuate uterus with R/L communicating tract
• Uterus bicornuate bicollis
• Combined bicornuate septate uterus (serosal indentation >1 cm)

6. Septate Uterus

• Partial septate uterus - septum length >1 cm and septum angle <90°
• Normal/arcuate uterus - septum length ≤1 cm and septum angle >90°
• Robert's uterus (asymmetric non-communicating hemi-cavity)
• Complete septate uterus with duplicated cervices and longitudinal vaginal septum
• Complete septate uterus with septate cervix and longitudinal vaginal septum
• Complete septate uterus, duplicated cervices, and obstructed R/L hemivagina

7. Longitudinal Vaginal Septum

• Longitudinal vaginal septum of variable length
• Longitudinal vaginal septum and uterus didelphys
• Longitudinal vaginal septum and complete septate uterus with duplicated cervix
• Obstructed R/L hemivagina and uterus didelphys
• Obstructed R/L hemivagina and complete septate uterus with duplicated cervices

8. Transverse Vaginal Septum

• Mid vaginal septum
• Distal vaginal septum (includes imperforate hymen spectrum)

9. Complex Anomalies

• Bicornuate uterus with bilateral obstructed endometrial cavities
• Uterus didelphys with communicating hemiuteri and unilateral R/L cervicovaginal atresia
• Obstructed R/L hemivagina, hemiuterus and single cervix with separate contralateral patent hemiuterus, cervix and vagina
• Bicornuate uterus with R/L communicating tract and transverse vaginal septum
• Uterus isthmus agenesis

Key Diagnostic Criteria (Septate vs. Bicornuate)

Important Features of MAC2021

• Educational elements for each anomaly: embryology, prevalence, clinical presentation, diagnosis, management
• Imaging subpages for each category: best screening tool, diagnostic strategy, examples in MRI, ultrasound, and HSG
• Overlap is expected - vaginal anomalies frequently co-occur with uterine/cervical ones; the classification allows cross-referencing
• Identifiable in scientific databases using standardized terminology for research purposes
• Designed to be used by providers across all disciplines (gynecology, radiology, urology, pediatrics, reproductive endocrinology)

Comparison: AFS 1988 vs MAC2021