Here is the complete ASRM Mullerian Anomalies Classification 2021 (MAC2021):
ASRM Mullerian Anomalies Classification 2021 (MAC2021)
Published in Fertility & Sterility, Vol. 116, No. 5, November 2021. MAC2021 classifies Mullerian anomalies into 9 categories using descriptive terminology (not numbered like the old 1988 AFS system). Anomalies may appear in more than one category because they represent a continuum of development with combined elements. Diagnosis is based on ultrasound (2D/3D), MRI, HSG, hysteroscopy, and/or laparoscopy.
Category 1: Mullerian Agenesis
Also known as: MRKH syndrome, Mayer-Rokitansky-Kuster-Hauser syndrome, vaginal agenesis
Subcategories:
- Mullerian agenesis (classic) - widely divergent atrophic uterine remnants, absent cervix and upper vagina
- Mullerian agenesis with bilateral atrophic uterine remnants with functional endometrium
- Mullerian agenesis with R/L (unilateral) atrophic uterine remnant with functional endometrium
Key features: No palpable uterus/cervix; vaginal canal absent or shallow dimple; evaluate for renal anomalies; presents with primary amenorrhea
Category 2: Cervical Agenesis
Subcategories:
- Cervical agenesis (complete)
- Distal cervical agenesis
Key features: Uterus present but cervix absent or partially absent; often presents with cyclic pelvic pain and hematometra
Category 3: Unicornuate Uterus
Subcategories:
- R/L unicornuate uterus (isolated)
- R/L unicornuate uterus with R/L distal atrophic uterine remnant (no endometrium)
- R/L unicornuate uterus with R/L distal uterine remnant with functional endometrium
- R/L unicornuate uterus with R/L associated atrophic uterine remnant (communicating or non-communicating)
- R/L unicornuate uterus with R/L uterine horn communicating at the level of the cervix
Category 4: Uterus Didelphys
Subcategories:
- Uterus didelphys with longitudinal vaginal septum (complete)
- Uterus didelphys with +/- longitudinal vaginal septum of variable length
- Uterus didelphys with obstructed R/L hemivagina (Herlyn-Werner-Wunderlich syndrome variant)
Category 5: Bicornuate Uterus
Subcategories:
- Bicornuate uterus - serosal indentation >1 cm (measured from the bicornual line)
- Bicornuate uterus with R/L communicating tract
- Uterus bicornuate bicollis (two cervices)
- Combined bicornuate septate uterus - serosal indentation >1 cm
Category 6: Septate Uterus
Subcategories:
- Septate uterus (complete) - septum reaches internal os
- Partial septate uterus - septum length >1 cm AND septum angle <90°
- Normal/arcuate uterus - septum length <1 cm AND septum angle >90° (MAC2021 combines arcuate with normal, reflecting limited clinical significance)
- Robert's uterus - asymmetric complete septum with one obstructed hemicavity
- Complete septate uterus with duplicated cervices and longitudinal vaginal septum
- Complete septate uterus with septate cervix and longitudinal vaginal septum
- Complete septate uterus with duplicated cervices and obstructed R/L hemivagina
Category 7: Longitudinal Vaginal Septum
Subcategories:
- Longitudinal vaginal septum of variable length (isolated)
- Longitudinal vaginal septum + uterus didelphys
- Longitudinal vaginal septum + complete septate uterus with duplicated cervix
- Obstructed R/L hemivagina + uterus didelphys
- Obstructed R/L hemivagina + complete septate uterus with duplicated cervices
Category 8: Transverse Vaginal Septum
Subcategories:
- Mid vaginal septum
- Distal vaginal septum
(Proximal/upper vaginal septum also recognized)
Category 9: Complex Anomalies
For anomalies that do not fit neatly into a single category or involve combined elements:
Subcategories:
- 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 Differences from AFS 1988 Classification
| Feature | AFS 1988 | MAC2021 |
|---|
| Categories | Numbered I-VII | Descriptive names (9 categories) |
| Cervical anomalies | Not included | Included |
| Vaginal anomalies | Not included | Included (2 dedicated categories) |
| Arcuate uterus | Separate category | Combined with normal |
| Diagnostic criteria | Vague | Standardized (e.g., septum >1 cm, angle <90°) |
| Format | Printable table | Interactive digital tool + printable |
| Complex anomalies | Not addressed | Dedicated category |
Educational Elements per Category (MAC2021 Interactive Tool)
Each category includes 5 elements:
- Presentation - symptoms, exam findings, differential diagnosis
- Imaging - MRI, ultrasound, HSG findings
- Associated anomalies - renal, skeletal, etc.
- Treatment - surgical and medical options
- Reproductive outcomes - fertility and pregnancy data
Reference: Pfeifer S et al. ASRM Mullerian Anomalies Classification 2021. Fertil Steril. 2021;116(5):1238-52. PMID: 34756294. An erratum was published in 2023 (Fertil Steril. 2023;119(6):1088).