Ambulatory Urology and Urogynaecology. Группа авторов

to apply pressure to the perineum to evacuate faeces

Figure 2.4 The endopelvic fascia in a post‐hysterectomy patient divided into DeLancey's biomechanical levels: level I, proximal suspension; level II, lateral attachment; level III, distal fusion.

      Level I Support

      The cervix and upper vagina are suspended by the endopelvic fascia (parametria) and condensations of the connective tissue, the uterosacral and cardinal ligaments. The uterosacral ligaments pass from the posterior aspect of the cervix and upper vagina, form the lateral boundaries of the pouch of Douglas, and attach to the anterior surface of the sacrum at the level of the sacrococcygeal joint up to the level of S3. The uterosacral ligaments are each 12–14 cm long and subdivided into distal (2–3 cm), intermediate (5 cm), and proximal (5–6 cm). The distal portion is commonly used to anchor the vaginal apex in McCall's culdoplasty. The proximal portion is diffuse in attachment and generally thinner. The intermediate portion is thick, well defined, and at least 2.5 cm away from the ureter and hence suitable for suspension procedures. The cardinal ligaments (transverse cervical) attach to the posterolateral pelvic walls from the cervix and lateral vaginal fornix. These attachments are referred to as the level I or suspensory support. Together, they support the lower uterus, cervix, and upper vagina. They also maintain vaginal length and a nearly horizontal vaginal axis supported by the levator plate. Failure of the level I support leads to uterine or vaginal vault prolapse (apical prolapse).

      Level II Support

The fascial attachment in the mid‐vagina extends from the lateral vaginal walls to the ATFP anteriorly and arcus tendineus rectovaginalis posteriorly. It maintains the midline position of the vagina directly over the rectum and prevents the descent of the anterior and posterior vaginal walls with increased intra‐abdominal pressure. The ATFP shares the same origin as ATLA at the ischial spine. However, it traverses infero‐medially to the ATLA before it inserts on the inferior aspect of the superior pubic rami over the origin of the puborectalis muscle. This explains the normal axis of the upper vagina, as the axis of both ATLA and ATFP are nearly horizontal in a standing woman (Figure 2.5). The endopelvic fascia blends with the vaginal muscularis anteriorly, the rectal muscularis posteriorly, and the perineal body inferiorly. The arcus tendineus rectovaginalis is approximately 4 cm in length and changes the axis of the distal vagina towards the vertical.

      The endopelvic connective tissue also extends as pubourethral ligaments, from the urethra to the posterior surface of the pubic bone, providing urethral support and maintenance of bladder neck closure during Valsalva manoeuvres. The bladder neck through its relation to the anterior vaginal wall is also indirectly supported by its attachment axis. Hence, failure of level II support leads not only to anterior and posterior vaginal wall prolapse but may also lead to SUI.

The differentiation between a ‘central cystocele’ and a ‘paravaginal defect’ in anterior compartment prolapse is based on the type of endopelvic fascia deficiency. In central cystocele (distension cystocele), there is weakening of the connective tissue in the midline, resulting in the loss of midline rugosity of the vaginal wall. A lateral cystocele or paravaginal defect results from lateral detachment of the fascia from the ATFP, and the central rugosity is preserved in these. Prior to surgical intervention, it is important to identify the type of anterior wall prolapse as either a lateral detachment or central defect in order to plan the optimal surgical technique.

Figure 2.5 The lateral attachments of the pubocervical fascia (PCF) and the rectovaginal fascia (RVF) to the pelvic sidewall. Also shown are the arcus tendineus fascia pelvis (ATFP), arcus tendineus fascia rectovaginalis (ATFRV) and ischial spine (IS).

      Level III Support

      The lower one‐third of the vagina is fused with the surrounding structures through the endopelvic fascia anteriorly to the distal urethra, posteriorly to the perineal body, and laterally to the pubovaginalis muscle and perineal membrane. Together they support and maintain the normal position of the distal one‐third of the vagina and introitus. The perineal body is critical for support of the lower part of the vagina and proper function of the anal canal.

Perineal descent can occur due to separation of the anchored perineal membrane from the perineal body and can contribute to defecatory dysfunction. Therefore, level III disruption anteriorly can result in SUI from urethral hypermobility, and posterior disruption can result in distal rectocele or perineal descent.

      The endopelvic fascia becomes the primary mechanism of support in circumstances when neuropathic injury or mechanical damage leads to pelvic floor muscle weakness. This may lead to loss of normal anatomic position if the ongoing stress overcomes the strength of the endopelvic fascial attachments. The resultant altered vector forces may lead to POP and/or visceral dysfunction. The goal of reconstructive pelvic surgery should be to recreate these supportive connections and restore the anatomical position of the pelvic organs while maintaining adequate vaginal length to maintain the vaginal apex in a natural position.

Conclusion

      A thorough understanding of pelvic anatomy is necessary prior to planning any urogynaecological procedure. The types of pelvic floor disorders and being aware of the risk factors help the surgeon in planning the appropriate surgery.

Further Reading

      1 Abrams, P., Cardozo, L., Fall, M. et al. (2002). The standardisation of terminology of lower urinary tract function: report from the Standardisation Subcommittee of the International Continence Society. Neurourol and Urodyn. 21 (2): 167–178.

      2 DeLancey, J.O. (1994 Aug). The anatomy of the pelvic floor. Current Opinion in Obstetrics & Gynecology 6 (4): 313–316.

      3 DeLancey, J.O.L. (2003). Functional anatomy of the pelvic floor. In: Imaging Pelvic Floor Disorders (eds. C.I. Bartram and J.O.L. DeLancey), 27–38. Berlin, Heidelberg: Springer.

      4 Iglesia, C.B. and Smithling, K.R. (2017). Pelvic organ prolapse. Am. Fam. Physician 96 (3): 179–185.

      5 MichiganUo (2018). Urinary Incontinence: an inevitable part of aging? National Poll on Health Aging. http://www.healthyagingpoll.org/sites/default/files/2018‐11/NPHA_Incontinence‐Report_

      6 Whitcomb, E.L., Rortveit, G., Brown, J.S. et al. (2009). Racial differences in pelvic organ prolapse. Obstet. Gynecol. 114 (6): 1271–1277.