OC16.08: Characteristics of a large cohort of 303 women with unicornuate uterus: subtypes and coexisting gynecological abnormalities

To characterise sub-types of unicornuate uterus and prevalence of benign comorbidities in a large cohort of women with unicornuate uterus. A retrospective case-control study carried out in a tertiary hospital between Jan 2008 and Sept 2020, including all women diagnosed with a unicornuate uterus on transvaginal or rectal ultrasound. A control group of women with normally formed uteri were matched for age, body mass index and ethnicity. The primary objective was to describe the frequency of sub-types of unicornuate uterus and coexisting urogenital anomalies and benign gynecological conditions. 303 unicornuate case were compared to 303 matched controls. 206/303 (68%) of women in the study group had a rudimentary horn, of which 5/206 (3%) were communicating and functional, 85/206 (41%) non-communicating and functional, and 116/206 (56%) non-functional non-communicating. 55% of women with a functional horn had it excised, the majority (78%) before the first pregnancy. Only 2% of non-functional horns were excised. Women with a functional horn were less likely to experience infertility than those with a non-functional horn (8% vs 17%, p = 0.03), but more likely to have endometriosis (24% vs 13%, p = 0.023), while a similar rate of adenomyosis occurred in both groups (25% vs 26%). Compared with controls, women with unicornuate uteri were more likely to be diagnosed with genitourinary anomalies (17% vs 0.3%, p=0.0001). Endometriosis (17% vs 7%, p = 0.01) and adenomyosis (26% vs 19%, p = 0.032) were more frequent in the unicornuate group, while fibroids were not (16% vs 15%, p = 0.9). 15% in the study group had an ectopic pregnancy (7 in the functional non-communicating horn), versus 8% in the control group (p=0.001). 30% of women with a unicornuate uterus have a functional horn which is associated with a higher risk of endometriosis and rudimental horn ectopic pregnancy. Women with a unicornuate uterus are more likely to have urogenital tract anomalies, endometriosis and adenomyosis, but not fibroids.