Comparative histological study of levels 1-3 supportive tissues using pelvic floor semiserial sections from elderly nulliparous and multiparous women

Aim: The connective tissue located between the uterine cervix and sacrospinous ligament (the uterospinous connective tissue; USCT) has recently been noted as the level 1 supportive tissue instead of the classical uterosacral ligament. We examined whether or not the USCT changes its histological architecture by vaginal delivery in correlation with the levels 2 and 3 supportive tissues. Methods: In the pelvic floors of 17 female cadavers (9 nuliparous and 8 multiparous), we compared histological architectures among the USCT, arcus tendineus fasciae pelvis (ATFP) and perineal membrane (PM). Results: The USCT was evident as a string-like tissue structure in multiparous women or a thick mesh in nuliparous women. It consistently contained fewer elastic and smooth muscle fibers than other levels. In contrast, the ATFP usually contained abundant elastic fibers and smooth muscle. Likewise, the PM also displayed a constant morphology. Conclusion: Although all three sites were likely to be injured by delivery, the USCT seemed to be more severely damaged and/or more difficult to be recovered than the ATFP and PM.