MRI-Based Structural Failure Comparison between Chinese and American White Women With Prolapse: A Case-Control Study.

Introduction and hypothesis: Although some evidence suggests that Chinese and white women might have different pelvic floor anatomy such as levator complex and connective tissue support for pelvic organs, it is unknown if these differences affect the mechanisms of pelvic organ prolapse. We sought to determine whether differences exist in MRI-based structural failure patterns between Chinese and American white women with prolapse.

Methods: This is a case-control study in different racial cohorts recruited in China and the USA. The Chinese cohort included 19 women with anterior-predominant prolapse and 24 controls with normal pelvic support. The American white cohort included 30 women with anterior-predominant prolapse and 30 controls. Both cohorts underwent the same clinical evaluation and MRI protocol. Three structural support systems were quantified on stress 3D MRI at maximal Valsalva: vaginal factors (length, width); connective tissue attachment (cervix, lateral paravaginal height); and hiatus factors (urogenital hiatus size, major levator ani injury). Abnormal structural support was defined as any measurement outside the normal range defined as the 5th to 95th percentile in controls from the respective cohort. The percentages of the women with abnormal support in the two cohorts were compared.

Results: Among those with prolapse, Chinese women were more likely than white women to have abnormally long vaginal length and width (90% vs 40%, p < 0.001; 53% vs 23%, p = 0.031 respectively). The occurrence of abnormal apical location, paravaginal location, and genital hiatus size ranged from 89 to 100% in Chinese women and from 63 to 80% in white women.

Conclusions: Prolapse in American white women most commonly involves structural failure of connective tissue attachments and hiatus factors and less frequently involves vaginal wall factors, whereas prolapse in Chinese women frequently involves all support structures.