KEY FACTS
Terminology
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Müllerian duct anomalies (MDA): Series of uterine malformations resulting from abnormal development, fusion, or resorption of müllerian ducts
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MDA types
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Müllerian agenesis or hypoplasia
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Unicornuate uterus
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Uterus didelphys
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Bicornuate uterus
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Septate uterus
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Arcuate uterus
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Ovaries are not involved
Imaging
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Abnormal configuration of endometrial cavity ± abnormal external contour of uterus
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3D ultrasound is vital for correct diagnosis, as it enables evaluation of fundus in true coronal plane
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Arcuate uterus
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Most common MDA
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Normal external uterine contour
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Septate uterus
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2nd most common MDA
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2 endometrial cavities, fibrous or muscular septum of variable length and thickness
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Convex outer uterine contour or cleft < 1 cm
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Intercornual angle < 75° suggests septate uterus
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Bicornuate uterus
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3rd most common MDA
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2 symmetric uterine horns, fused inferiorly; deep fundal cleft > 1 cm
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Intercornual distance > 4 cm favors bicornuate uterus
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Intercornual angle > 105° suggests bicornuate uterus
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Unicornuate uterus
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Curved and elongated, banana-shaped single uterine horn and endometrium
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Uterus didelphys
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2 separate noncommunicating, divergent uterine horns with 2 cervices; deep fundal cleft
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Vaginal septum in 75%
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Müllerian agenesis or hypoplasia
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Absent or small rudimentary uterus
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± hematometros
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DES uterus (T-shaped)
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MR to clarify anatomy, relationship of pelvic organs
Top Differential Diagnoses
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Imperforate hymen
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Cervical stenosis
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Pyometra
Pathology
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MDAs occur during 1 of 3 phases of development
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Organogenesis phase: Uterine agenesis, hypoplasia, unicornuate
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Fusion phase: Didelphys, bicornuate
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Septal resorption phase: Septate, arcuate
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Clinical Issues
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1-5% prevalence in general population
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Symptoms depend on variant; many asymptomatic
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May present with primary amenorrhea or dysmenorrhea at menarche, cyclical pelvic pain and pressure or with obstetric-/fertility-related complications
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Endometriosis if obstruction present
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Renal anomalies in 30-50%: renal agenesis (most common)
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Ectopic kidney, horseshoe kidney, duplicated collecting system, renal dysplasia
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Scanning Tips
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Image outer uterine contour
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Essential for differentiation of septate vs. bicornuate uterus
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Image renal fossae to assess for renal agenesis
. The cavity is divided with myometrium in the superior aspect of the septum, although normal zonal anatomy is not present in this portion 
.
separated by myometrial tissue 
. An early gestational sac 
is present on the left side. Evaluation of the external uterine contour was necessary to confirm this as a septate uterus.
indenting the fundal endometrium. The coronal reconstruction readily depicts the normal convex outer uterine contour 
of this septate uterus.
extending into the fundal endometrium with a normal convex outer uterine contour 
, consistent with septate uterus.
