Comparative histological analysis of anterior vaginal wall in women with pelvic organ prolapse or control subjects. A pilot study

The purpose of this study was to compare smooth muscle content of anterior vaginal wall in women with pelvic organ prolapse (POP) and control subjects. Specimens were taken in the midline from the apex of anterior vaginal cuff from eleven women with POP and eight control subjects operated for hysterectomy without prolapse. Masson's trichrome stain was used to determine the distribution of collagen in the extracellular matrix of the vaginal muscularis and to quantify the collagen in area of interest. Slides of alpha smooth muscle actin were detected using antibodies. Morphometric analysis was used to compare and to quantify the smooth muscle content of the vaginal muscularis. Fractional area of nonvascular vaginal smooth muscle of women with POP was significantly decreased in comparison to control subjects (41.9 vs 61.9%, p = 0.005). Fractional area of connective tissue was significantly increased (56.8 vs 35%, p = 0.004). Fractional area of blood vessels was similar (2.2 vs 3.4%, p = 0.20).