Pelvic Prolapse: Diagnosing and Treating Cystoceles, Rectoceles, and Enteroceles

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Medscape General Medicine. 1998;1(3) 

In This Article

Pelvic Prolapse: Anatomy and Pathophysiology

All pelvic prolapse conditions and urethral hypermobility result from a phenomenon called pelvic-floor relaxation. The pathophysiology of this relaxation can often be linked to multiparity, muscle weakness associated with advanced age, hormonal insufficiency, obesity, neurogenic weakness of the pelvic-floor musculature, connective-tissue disorders, or prolonged physical activity. However, pelvic relaxation can also occur in young, inactive patients who have never had children. One single etiology is rarely applicable.[1,2] Although inherent tissue weakness and childbearing are among the most common causes of vaginal prolapse conditions, an additional cause is a prior hysterectomy. If the vaginal vault is not sufficiently resuspended and the cul-de-sac is obliterated, vault prolapse and/or enterocele are common sequelae.

The main support for the pelvic viscera is provided by a group of muscles known collectively as the levator ani. In the normal individual, the levator ani muscles keep the pelvic floor closed, allowing the pelvic and abdominal viscera to rest on the levator ani, significantly reducing tension on the supporting fascia and ligaments. The opening in the levator ani muscle group, through which the vagina and urethra pass, is called the urogenital hiatus. The rectum passes through the rectal hiatus.

In the normal individual, the pelvic-floor musculature supports most of the weight of the pelvic viscera, whereas the pelvic ligaments stabilize these structures in position, much like a ship's weight is supported by the water and the moorings simply keep the ship from straying away from the dock.[3,4] When the levator ani is damaged and unable to adequately support the weight of the pelvic organs, a disproportionate amount of force is placed on the inherently weak ligaments. These structures, which are not true ligaments, are not designed to carry the increased load and may fail over the course of time, allowing the bladder, rectum, small bowel, or uterus to prolapse through the vagina. The resulting prolapse condition, however, depends upon which structural units fail.

The vagina can be divided into 3 major sections: upper, middle, and lower. The upper portion, the vaginal vault or apex, is stabilized by the lower paracolpium, which contains the cardinal and uterosacral ligaments. These same ligaments are also the supportive structures for the cervix and lower uterus. Uterine prolapse is associated with damage to these supportive structures, as is vault prolapse, which typically occurs after these ligaments are divided during hysterectomy. An enterocele, which is a true vaginal hernia with small bowel trapped within a peritoneal sac, can also occur at the vaginal apex.

The middle portion of the vagina is attached laterally to the pelvic sidewalls via the lower portion of the paracolpium to the arcus tendineus, which creates the typical superior lateral vaginal sulcus seen on physical exam. Pubocervical fascia stretch between these lateral attachments to support the anterior vaginal wall and underlying bladder. A cystocele occurs when damage to the pubocervical fascia in the central or lateral areas (or both) allows the bladder to protrude into the vagina. In similar fashion, the posterior vaginal wall in the mid-vagina is supported centrally and laterally by rectovaginal fascia, which are attached to the fascia of the levator ani musculature. These attachments prevent the rectum from protruding into the vagina and causing a rectocele.

The distal vagina is firmly attached to surrounding structures such as the urethra and symphysis pubis anteriorly, the levator ani laterally, and the perineal musculature posteriorly. The fascia is much thicker and well developed under the urethra and bladder neck, allowing increased support for the bladder neck. Defects in vaginal support can occur singly or in combination in various degrees, leading to complex pelvic prolapse conditions. This is why a clear understanding of the anatomy, a thorough physical exam, and knowledge of the available procedures are all important.