Genital Hiatus Size and the Development of Prolapse Among Parous Women

Abstract

Objective: In cross-sectional studies, pelvic organ prolapse is strongly associated with genital hiatus (GH) size. The objective of this study was to estimate prolapse incidence by the size of the GH among parous women followed prospectively.

Methods: Data were derived from a longitudinal study of pelvic floor disorders. Participants were followed annually for 2-9 years. Genital hiatus size and prolapse beyond the hymen were assessed with annual pelvic organ prolapse quantification examinations. Kaplan-Meier methods described prolapse-free survival as a function of GH size. Accounting for changes over time in GH size, lognormal models were used to estimate prolapse-free survival by GH size. This analysis was repeated separately for women who gave birth exclusively by cesarean versus those with at least one vaginal birth.

Results: Among 1,492 participants, median age at enrollment was 38 years; 153 (10.3%) developed prolapse over 2-9 years. The cumulative probability of prolapse increased substantially as the size of the GH increased. Lognormal models predicted that the estimated median time to develop prolapse would be 33.4 years for women with a persistent GH of 3 cm; in contrast, the estimated median time to develop prolapse would be 5.8 years for a GH of 4.5 cm or greater. Considering separately women who gave birth by cesarean versus those with at least 1 vaginal birth, GH size drastically modified prolapse risk in both birth groups.

Conclusions: Prolapse incidence is strongly associated with GH size, regardless of delivery mode. These findings suggest that a wider GH is an important predictor of future prolapse risk.

Figure 1:

Kaplan-Meier survival estimates for prolapse-free survival, as a function of GH category. Corresponding lognormal models (described in the Supplemental Table) are overlaid, estimating prolapse-free survival as a function of GH category. P-value for the null hypothesis of no difference between the five GH categories was <0.001.

Figure 2:

Lognormal models (fully described in the Supplemental Table), estimating prolapse-free survival as a function of GH category up to 45 years after first delivery. Survival estimates of those persisting in a given GH category over time are represented by dashed lines. Survival estimates for three hypothetical women transitioning between GH categories are represented by solid lines (a, b, and c). Transitions between GH categories are indicated by changes in color of the solid line.

Figure 3:

Kaplan-Meier survival estimates for prolapse-free survival, as a function of GH category, stratified by birth type. Corresponding lognormal models (fully described in the Supplemental Table) are overlaid, estimating prolapse-free survival as a function of GH category. P-values for the null hypothesis of no differences between the GH categories were <0.001 and <0.001 for cesarean only and vaginal delivery groups, respectively.