Uterine Anomaly Classification (ASRM 2021)

Step-by-step decision

Choose step by step as prompted; reaching an endpoint gives the management recommendation. You can go back a step or restart anytime.

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Full pathway

1. [Decision] External fundal contour + indentation depth
   External fundal contour + indentation depth (septate vs bicornuate)? (ASRM MAC2021 has nine classes. The key is the external fundal contour: MRI is best (multiplanar + zonal anatomy + external contour), 3D transvaginal ultrasound is the primary choice (coronal plane); HSG cannot assess the external contour. Always check the kidneys (often associated renal anomaly/OHVIRA obstructed hemivagina).)
   • Normal external contour/external indentation <1 cm + internal septum >1 cm, angle <90 degrees → Septate uterus · hysteroscopic resection
   • External fundal indentation >1 cm + separated horns (intercornual distance often >4 cm) → Bicornuate uterus · usually no surgery
   • Internal indentation <1 cm, normal external contour (arcuate/normal) → Arcuate/normal variant
   • Other (unicornuate/didelphys/hypoplasia/vaginal septum, etc.) → Other anomalies · always check the urinary tract
2. [End] Septate uterus · hysteroscopic resection
   Septate uterus (normal external contour + internal septum >1 cm, angle <90 degrees): hysteroscopic septum resection can improve fertility outcomes; the septum is T2-low (fibrous)/intermediate (muscular); may extend to the cervix (complete septum)/vagina.
3. [End] Bicornuate uterus · usually no surgery
   Bicornuate uterus (external fundal indentation >1 cm, separated horns): fusion anomaly; usually no surgery (laparoscopic metroplasty only for recurrent loss); management differs greatly from septate, so external contour interpretation is critical.
4. [End] Arcuate/normal variant
   Arcuate/normal (internal indentation <1 cm, normal external contour): MAC2021 classes it as a normal variant, little clinical significance, no intervention needed.
5. [End] Other anomalies · always check the urinary tract
   Other anomalies (unicornuate, didelphys, hypoplasia/MRKH, longitudinal/transverse vaginal septum, etc.): descriptive classification by MAC2021; always check the urinary tract (renal agenesis/OHVIRA obstructed hemivagina); manage by type and fertility/obstruction status.

Source guidelines & references

• ASRM Mullerian anomaly classification 2021 (Fertil Steril 2021) · source ↗
• Mullerian anomaly imaging and classification (Insights Imaging 2025)

This pathway is our own synthesis of the decision logic in the guidelines above (not the guideline verbatim); thresholds and workflows change as guidelines update — in practice follow the latest guideline, your institution's protocol and the individual patient.

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