An arcuate uterus is a mildly variant shape of the uterus. It is technically one of the Müllerian duct anomalies, but is often classified as a normal variant. It is the uterine anomaly that is least commonly associated with reproductive failure. Arcuate uterus can be characterized with ultrasound or MRI.
An arcuate uterus is characterized by a mild indentation of the endometrium at the uterine fundus. It occurs due to a failure of complete resorption of the uterovaginal septum, and is the most common Mullerian duct anomaly, affecting 3.9% of the general population .
General features include:
- normal fundal contour
- no division of uterine horns
- smooth indentation of fundal endometrial canal: the depth of indentation is usually considered to be <1 cm
- increased transverse diameter of uterine cavity
On hysterosalpingograms there is opacification of the endometrial cavity demonstrates a single uterine canal with a broad saddle-shaped indentation of the uterine fundus.
A normal external uterine contour is noted, with a broad smooth indentation on the fundal segment of the endometrium. There should not be division of the uterine horns.
A normal external uterine contour is maintained. The myometrial fundal indentation is smooth and broad, and the signal intensity of this region is isointense to normal myometrium.
- septate uterus
- arcuate uterus and septate uterus exist on a spectrum from most to least resorption of the uterovaginal septum, respectively
- bicornuate uterus
- arcuate uterus can be distinguished from a bicornuate uterus on the basis of its complete fundal unification (i.e. an arcuate uterus has a normal or slightly indented external fundal contour, whereas a bicornuate uterus has a more marked fundal indentation, ≤5 mm above the level of the uterine horns)