Rectocele 

Pelvic organ prolapse (POP) is a common condition that is increasing in incidence. Many cases of prolapse of the posterior vaginal wall occur along with other pelvic support defects. Pelvic surgeons who treat rectocele must have an excellent understanding of the normal anatomy, interactions of the connective tissue and muscular supports of the pelvis, and the relationship between anatomy and function. These pelvic support defects may or may not cause symptoms. Pelvic pressure, the need to splint the perineum to defecate, impaired sexual relations, difficult defecation, and fecal incontinence are some of the symptoms that have been described in patients with rectoceles. Whether prolapse is the cause or result of these symptoms is uncertain.

This article focuses on (1) current knowledge regarding the relationship of rectocele anatomy and function and (2) useful evaluations and treatments for women with rectoceles and defecation disorders.

The surgical treatment of rectocele since the early 19th century has been the posterior colporrhaphy. This procedure was originally designed to repair perineal tears and included plication of the pubococcygeus muscles and the posterior vaginal wall (effectively creating a perineal shelf and partially closing the genital hiatus) with reconstruction of the perineal body.^[1]

Recently, Richardson has advocated the site-specific repair of discrete breaks or tears in the rectovaginal septum.^[2] This approach aims for a more anatomic repair. Other considerations for treatment include the approach (transvaginal vs transanal) and the introduction of different types of grafts or "kits" to attempt improvement of the longevity of the procedure.

Rectocele is defined as herniation or bulging of the posterior vaginal wall, with the anterior wall of the rectum in direct apposition to the vaginal epithelium.

Frequency

POP is very common, and it is the indication for more than 200,000 surgeries in the United States annually.^[3] The number of women seeking care for pelvic organ prolapse is predicted to increase by 45% over the next few years.

Ambulatory women have a reported prevalence rate of pelvic organ prolapse of 30-93%. One of the difficulties in reviewing studies of pelvic organ prolapse is that these studies include all support defects (eg, defects of the vaginal apex, anterior wall, posterior wall), although most women have support defects at multiple locations. It is difficult to determine the prevalence of POP in ambulatory women, since most POP is mild, with prolapse beyond the vaginal introitus occurring in less than 5% of cases.^[4]

Data on symptomatic women with prolapse are somewhat more robust. In a review of 149,544 women, Olsen et al found an 11.1% lifetime risk of surgery for pelvic organ prolapse or urinary incontinence. Approximately 40% of these women had posterior support defects.^[5]

Thus, POP and rectocele are relatively common, although the supporting data are limited. The incidence of POP and rectocele increases with age, parity, and BMI. However, even nulliparous women may present with a clinically significant rectocele, albeit relatively uncommon.

Rectocele and other forms of POP are the result of women attaining an erect bipedal posture. Etiologically, most cases are the result of vaginal childbirth and chronic increases in intra-abdominal pressure. In some patients, rectocele is thought to develop as a result of congenital or inherited weaknesses within the pelvic support system.

A number of iatrogenic factors may contribute to POP, including failure to adequately correct all pelvic support defects during pelvic reconstructive surgery. In some patients, the failure to reattach the endopelvic fascia to the perineal body at the time of vaginal delivery leads to a site-specific defect in the endopelvic fascia. Additionally, procedures that alter the direction of pelvic forces can cause areas to prolapse that previously had been adequately supported. Examples include (1) ventral suspensions of the urethra, uterus, or vagina that increase exposure of the cul-de-sac to increases in intra-abdominal pressure; (2) posterior fixation of the vaginal apex; (3) failure to detect and correct an occult enterocele; and (4) excessive shortening of the vagina.

Rectocele is a defect of the rectovaginal septum, not the rectum. The pelvic surgeon must know the anatomy of the pelvic floor and the other supports of the vagina in order to diagnose and treat this disorder.

The muscular support of the pelvis is from the pelvic diaphragm. The pelvic diaphragm is made up of a group of paired muscles that include the levator ani and coccygeus muscles. The levator ani are composed of the puborectalis, pubococcygeus, and ileococcygeus muscles. These muscles have their origin at the pubic rami on either side of the midline at the level of the arcus tendineus levator ani. The muscle fibers of the levator ani pass lateral to the vagina and rectum, creating a sling surrounding the genital hiatus. They also create the pelvic floor posteriorly and laterally. When a woman contracts the levator ani, the pelvic diaphragm provides a horizontal shelf where the pelvic viscera lie and the genital hiatus closes.

The thin membranous connective tissue in the rectovaginal septum (and surrounding the entire vaginal tube) is called the Denonvilliers aponeurosis (fascia) or endopelvic fascia and is fused to the underside of the posterior vaginal wall. This rectovaginal fascia extends downward from the posterior aspect of the cervix and cardinal-uterosacral ligaments to its attachment on the upper margin of the perineal body; then, it laterally extends to the fascia over the levator ani muscles. The cardinal and uterosacral ligaments pull the vagina horizontally toward the sacrum, suspending it over the muscular levator plate.

The perineal body is located between the vaginal introitus and anus. It is the attachment for the perineal membrane (bulbocavernosus muscles, superficial transverse perineal muscles, and investing fascia), a portion of the levator ani, the external anal sphincter, and the rectovaginal (endopelvic) fascia. Through its attachment to the cardinal and uterosacral ligaments, the rectovaginal septum stabilizes the perineal body, which is essentially suspended from the sacrum. The perineal body is further stabilized through the lateral attachments of the perineal membrane to the ischiopubic rami. Between the lateral and superior support, the downward mobility of the perineal body is limited. However, if this attachment is separated, as can occur during childbirth, the perineal body can become more mobile, leading to rectocele and perineal descent.

Patients with rectocele often present with feelings of pelvic pressure, a sensation of "bearing-down," or a perception that something is "falling out." Symptoms are often accentuated by standing and lifting and relieved by lying down. Symptoms directly related to the prolapse include the sensation of a mass or bulge in the vagina, pelvic pressure and pain, low back pain, and difficulty with intravaginal intercourse. Symptoms directly related to rectocele include defecatory dysfunction, inability to completely evacuate the distal rectum without straining, constipation, and dyspareunia.^[6] However, constipation is considered a colonic motility disorder not treated by posterior surgery.^[7]

The pelvic examination findings should define the degree of prolapse and help determine the integrity of the connective tissue and muscular support of the pelvic organs. The pelvic examination is best performed with the patient in the dorsal lithotomy position, with her head elevated 45° (which allows for maximal Valsalva). Rectocele is suspected when posterior wall bulging is noted.^[6]

The extent of prolapse must be documented. One method is to measure the degree of descent with respect to the hymenal ring. The Pelvic Organ Prolapse Quantitation examination is the most widely accepted at this time and has been adopted by the International Continence Society, the American Urogynecologic Society, and the Society of Gynecologic Surgeons. The 9 measurements made are 6 topographical points on the vaginal walls, 2 topographical points on the perineum, and vaginal length.^[8]

All portions of the vagina should be evaluated. This includes the vaginal apex, the anterior wall, and the posterior wall. The posterior wall is assessed while supporting the vaginal apex and anterior wall with a Sims speculum or with the posterior blade of a Graves speculum. This allows identification of the specific location of the defect in the rectovaginal fascia. The examiner may note that the rugae in the vaginal epithelium are lost overlying the defect in the endopelvic fascia. Generally, a pocket is observed just above the anal sphincter. Anterior displacement of the rectal wall observed upon rectovaginal examination is diagnostic of rectocele.^[9]

A rectovaginal examination provides information regarding the integrity of the rectovaginal fascia, perineal body, and possible identification of an enterocele.

In a healthy woman, the perineum should be located at the level of the ischial tuberosities or within 2 cm of them. Diagnosis of perineal descent is made if the perineum is noted to be below this level either at rest or with straining. In a patient with perineal descent, widening of the genital hiatus and perineal body and flattening of the intergluteal sulcus may be seen. The degree of perineal descent can be objectively measured with a thin ruler placed in the posterior introitus at the level of the ischial tuberosities. Descent is measured as the distance the perineal body moves when the patient strains.

The bimanual examination is used to investigate the location, size, and tenderness of the cervix, uterus, bladder, and adnexa. The pelvic diaphragm should be assessed for integrity, as should the strength, duration, and anterior lift of the contraction. The firm muscular sling of the puborectalis should be palpable posteriorly because it creates a 90° angle between the anal and rectal canals. Voluntary contraction of this muscle pulls the examining finger anteriorly toward the muscle's insertion on the pubic rami.

Generally, treatment is determined by the age of the patient, the desire for future fertility, the desire for coital function, the severity of symptoms, the degree of disability, and the presence of medical complications. Indications for surgery include the desire for definitive surgical correction of the mass or bulge in the vagina, pelvic pressure and pain, low back pain, difficulty with intravaginal intercourse, recurrent vaginal ulcerations due to pessary use, or fecal incontinence that the patient deems unacceptable.

Histologically, the apex of the posterior vaginal wall consists of squamous epithelium, a superficial and deep muscularis layer and an adventitial layer. The fibromuscular layer is commonly called the rectovaginal fascia. Kleeman et al have described the histology of the rectovaginal septum. The apical portion is mostly adipose tissue while the midportion consists of an adventitial layer containing fat, fibrous tissue, blood vessels, nerves, and elastic fibers. The distal portion at the level of the perineal body contains dense connective tissue.^[10]

Anatomically, the pelvic organs are maintained within the bony pelvis by levator ani muscles that are posteriorly fused (pelvic floor). The levator ani muscles are attached to the bony pelvis anteriorly and posteriorly; laterally, they are attached to the arcus tendineus musculi levatoris ani, which overlie the obturator internus muscles of the pelvic sidewalls. The anterior separation between the levator ani is called the levator hiatus. Inferiorly, the urogenital diaphragm covers the levator hiatus. The urethra, vagina, and rectum pass through the levator hiatus and urogenital diaphragm as they exit the pelvis. The posterior joining of the levator ani in the midline by the anococcygeal ligament forms the levator plate. DeLancey has described the 3 levels of pelvic support.^[11]

The perineal body is a central point for the attachment of the perineal musculature. The perineal body lies beneath and supports the pelvic diaphragm. The distal posterior wall of the vagina is fused to the ventral surface of the perineal body. The perineal body is also important to the support of the rectum. The pelvic organs, their interrelationships, and their support systems must be thought of conceptually and functionally in 3 dimensions (see above images).

Although the contents of the abdominal cavity bear down on the pelvic organs, they remain suspended in their relation to each other and to the underlying levator sling and perineal body. Each organ is capable of independent function because it is separated from other organs by connective-tissue spaces within the endopelvic connective-tissue support system. The normal tonic contraction of the levator ani muscles supports the pelvic organs from below and contributes to urinary and fecal continence. Relaxation of the levator ani muscles allows descent of the pelvic organs and aids urination and defecation.

Current anticoagulation and a medical risk profile that exceeds the benefits gained from surgical treatment of rectocele are contraindications for this somewhat elective procedure.