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Müllerian anomalies (also known as Müllerian duct anomalies or MDAs) are congenital malformations of the female reproductive tract resulting from abnormal development, fusion, or resorption of the paired Müllerian (paramesonephric) ducts during embryogenesis. They affect the uterus, fallopian tubes, cervix, and upper vagina.

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https://www.youtube.com/watch?v=attcQgvt5Iw

https://www.youtube.com/watch?v=pZLxjIY9u9g

Embryology

Three critical stages:

Stage Description Failure Leads to
1. Formation Development of Müllerian ducts (6th week) Aplasia or hypoplasia (e.g., MRKH syndrome)
2. Fusion Union of paired ducts (10–13 weeks) Didelphys or bicornuate uterus
3. Septal resorption Absorption of central septum (13–17 weeks) Septate uterus

![Three stages of Müllerian Duct (MD) development.

A. During the first stage, MDs form, elongate, and canalize. B. MDs fuse together in midline as well as to the sinovaginal bulb portion of the genitourinary sinus (SVB) in fusion stage. The Wolffian ducts regress (WD). C. Finally, during the resorption phase, the septum between MDs resorbs, creating patent uterine cavity (UT), cervix, and upper vagina. The vaginal plate canalizes to form lower vagina (V).

Vertical Septum (VS); Fallopian Tube (FT); Transverse Septum (TS)

Pitot, M.A., Bookwalter, C.A. & Dudiak, K.M. Müllerian duct anomalies coincident with endometriosis: a review. Abdom Radiol 45, 1723–1740 (2020). https://doi.org/10.1007/s00261-020-02465-y](attachment:4a34a457-1e7c-4e01-9da9-27f5010c177a:261_2020_2465_Fig1_HTML.webp)

Three stages of Müllerian Duct (MD) development.

A. During the first stage, MDs form, elongate, and canalize. B. MDs fuse together in midline as well as to the sinovaginal bulb portion of the genitourinary sinus (SVB) in fusion stage. The Wolffian ducts regress (WD). C. Finally, during the resorption phase, the septum between MDs resorbs, creating patent uterine cavity (UT), cervix, and upper vagina. The vaginal plate canalizes to form lower vagina (V).

Vertical Septum (VS); Fallopian Tube (FT); Transverse Septum (TS)

Pitot, M.A., Bookwalter, C.A. & Dudiak, K.M. Müllerian duct anomalies coincident with endometriosis: a review. Abdom Radiol 45, 1723–1740 (2020). https://doi.org/10.1007/s00261-020-02465-y

Classification

American Society for Reproductive Medicine (ASRM) 2021 Classification:

Class Anomaly Description
I Hypoplasia/Aplasia Absent uterus/vagina (e.g., ‣ )
II ‣ Incomplete formation of one Müllerian duct; may have rudimentary horn
III ‣ Complete failure of fusion → 2 uteri, 2 cervices ± vaginal septum
• Variant: ‣
IV ‣ Partial fusion defect → 1 cervix, 2 uterine horns
V ‣ Failure of septal resorption → fibrous or muscular septum
VI ‣ Mild indentation of the fundus (<10 mm depth); variant of normal
VII DES-related anomaly ‣ ; due to in utero diethylstilbestrol exposure

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![Classification of MDAs on the basis of the American Society for Reproductive Medicine system.

Image courtesy of Joanna Culley, BA Behr SC, Courtier JL, Qayyum A. Imaging of Müllerian Duct Anomalies. RadioGraphics. 2012;32(6):E233-E250. doi:https://doi.org/10.1148/rg.326125515](https://s3-us-west-2.amazonaws.com/secure.notion-static.com/52442e06-da2c-4a76-a12a-1613cb93ba39/Untitled.png)

Classification of MDAs on the basis of the American Society for Reproductive Medicine system.

Image courtesy of Joanna Culley, BA Behr SC, Courtier JL, Qayyum A. Imaging of Müllerian Duct Anomalies. RadioGraphics. 2012;32(6):E233-E250. doi:https://doi.org/10.1148/rg.326125515

Clinical Implications

Reproductive complications: