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A unicornuate uterus is a rare Müllerian duct anomaly that arises from incomplete or failed development of one of the paired Müllerian ducts, resulting in a single, banana-shaped uterus.

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It accounts for approximately 5% of Müllerian anomalies and is often associated with a rudimentary horn, which may or may not communicate with the main uterine cavity.

Embryology

• During normal development, both Müllerian ducts form and fuse to create the uterus.
• In a unicornuate uterus, one duct fails to develop (or is hypoplastic), leading to:
  • A single-sided uterus
  • Often a contralateral rudimentary horn, which may:
    • Communicate with the main horn
    • Be non-communicating
    • Contain functional endometrium or be fibrous

Classification

AFS/ASRM Classification

![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 Features

• Asymptomatic in some cases
• May present with:
  • Recurrent miscarriage
  • Infertility
  • Premature delivery or fetal malpresentation
  • Cyclic pelvic pain (if non-communicating functional horn)
  • Dysmenorrhea
• Often diagnosed during evaluation for reproductive failure

Associated Anomalies

• Renal anomalies in up to 40%
  • Most commonly: ipsilateral renal agenesis
  • Also: ectopic kidney, horseshoe kidney

Radiology