Characterizing the phenotype of advanced pelvic organ prolapse.

OBJECTIVE: Genetic studies require a clearly defined phenotype to reach valid conclusions. Our aim was to characterize the phenotype of advanced prolapse by comparing women with stage III to IV prolapse with controls without prolapse.

METHODS: Based on the pelvic organ prolapse quantification examination, women with stage 0 to stage I prolapse (controls) and those with stage III to stage IV prolapse (cases) were prospectively recruited as part of a genetic epidemiologic study. Data regarding sociodemographics; medical, obstetric, and surgical history; family history; and body mass index were obtained by a questionnaire administered by a trained coordinator and abstracted from electronic medical records.

RESULTS: There were 275 case patients with advanced prolapse and 206 controls with stage 0 to stage I prolapse. Based on our recruitment strategy, the women were younger than the controls (64.7 ± 10.1 vs 68.6 ± 10.4 years; P<0.001); cases were also more likely to have had one or more vaginal deliveries (96.0% vs 82.0%; P<0.001). There were no differences in race, body mass index, and constipation. Regarding family history, cases were more likely to report that either their mother and/or sister(s) had prolapse (44.8% vs 16.9%, P<0.001). In a logistic regression model, vaginal parity (odds ratio, 4.05; 95% confidence interval, 1.67-9.85) and family history of prolapse (odds ratio, 3.74; 95% confidence interval, 2.16-6.46) remained significantly associated with advanced prolapse.

CONCLUSIONS: Vaginal parity and a family history of prolapse are more common in women with advanced prolapse compared to those without prolapse. These characteristics are important in phenotyping advanced prolapse, suggesting that these data should be collected in future genetic epidemiologic studies.