Objective: To investigate the histological characteristics in uterine ligaments of stress urinary incontinence (SUI) and pelvic organ prolapse (POP); to detect the alteration of collagen ultrastructure in uterine ligaments that contribute to SUI and POP; to study the relationship between collagen alteration and SUI and POP.
Methods: The cardinal ligament (Car lig.) and uterosacral ligaments (U-S lig.) samples were obtained from 73 subjects suffering from SUI, or normal controls who underwent hysterectomy. Collagen ultrastructure was examined with transmission electron microscopy (TEM).
Results: 1) The smooth muscle fascicles in the patients with SUI and POP were thinner. Arrangement of smooth muscle fascicles was in disorder. 2) The collagen constituting the ligaments was active in metabolism. The mean collagen fibril diameters in the SUI and POP groups were about 25% larger than that in the control groups (p < or = 0.01). 3) Histological characteristics of the Car lig. and the U-S lig. were similar.
Conclusions: 1) The Car lig. and U-S lig. are homologous. Abnormalities in arrangement of smooth muscles and the collagen ultrastructure were obviously seen in SUI and POP 2) The collagen fibril diameter in the SUI and POP subgroups was significantly larger than that in the control groups. Those ligaments are probably less elastic and more likely to break. Predominance of collagen degradation during tissue repair may contribute to POP and SUI.