Uterine anomalies. How common are they, and what is their distribution among subtypes?

To establish the prevalence and distribution of uterine anomalies in the general population and to enumerate them among septate, bicornuate, didelphic, unicornuate, hypoplastic/aplastic and solid forms.

A Medline search and standard reference tracing were employed to locate 47 studies from 14 countries regarding the prevalence and distribution of uterine anomalies. Twenty-two studies involving 573,138 women undergoing universal screening for uterine malformations were analyzed to establish the prevalence of uterine anomalies among fertile women. A separate analysis of uterine anomalies among 6,512 infertile women was also performed. Nineteen studies incorporating 1,092 fertile and 456 infertile women with unselected uterine anomalies were reviewed to establish the distribution of müllerian malformations among major subtypes. Seventeen studies incorporating 161 women with unicornuate uteri were analyzed to establish the distribution of unicornuate müllerian defects among various subtypes, including those with and without cavitary contralateral uterine horns.

Uterine anomalies were identified in 1 in 594 fertile women (0.17%) and in 1 in 29 infertile women (3.5%). This difference was statistically significant (chi 2 = 3,424, df = 1, P < .00001). The prevalence of uterine anomalies in the general population was 1 in 201 women (0.50%). Their distribution was: 7% arcuate, 34% septate, 39% bicornuate, 11% didelphic, 5% unicornuate, and 4% hypoplastic/aplastic/solid and other forms.

Congenital uterine malformations are more common than generally recognized. Knowledge concerning their prevalence and varieties is important in recognizing and managing the obstetric and gynecologic complications that may result.