These site-specific defects can be transverse or longitudinal through the inferior, middle, or superior regions of the rectovaginal septum (36). Enterocele is a herniation of a peritoneal sac and bowel through the pelvic ﬂoor, typically between the uterus or vaginal cuff and rectum. It is more common following hysterectomy and retropubic urethropexy. There are two theories surrounding the formation of an enterocele. The first theory implicates a defect in the fibromuscular endopelvic fascia of the vagina, allowing peritoneum and bowel to herniate. The second theory attributes its formation to a support defect with full thickness protrusion, including endopelvic fascia (37). Ultimately, the mechanism might be attributed to a combination of the two theories because some support defects are secondary to superior breaks in the rectovaginal and pubocervical fascia. Patients with rectocele and enterocele may have similar symptoms, including pelvic pressure, vaginal protrusion, obstipation, fecal incontinence, and sexual dysfunction. Although associations have been made between defecatory dysfunction and advanced stages of pelvic organ prolapse, a causal relationship remains to be established. Controversy remains as to whether anatomic herniation is the cause of these symptoms or the effect of underlying colonic dysfunction, chronic constipation, and straining.
Descending perineum syndrome is defined as descent of the perineum (at the level of the anal verge) beyond the ischial tuberosities during Valsalva. Excessive perineal descent was first described in the colorectal literature by Parks et al. in 1966 (38,39). It occurs as a result of inferior detachment of the rectovaginal septum from the perineal body. As the condition progresses, the patient can develop pudendal neuropathy from stretch injury. Perineal descent has been associated with a variety of defecatory disorders, including constipation, fecal incontinence, rectal pain, solitary rectal ulcer syndrome, rectocele, and enterocele (40).
Rectal Intussusception Rectal intussusception or intrarectal prolapse is the circumferential prolapse of the upper rectal wall into the rectal ampulla but not through the anal verge.
It occurs most often in women in their fourth and fifth decades. The most common symptoms are obstructive, including incomplete emptying, manual disimpaction, splinting, pain with defecation, and bleeding. Other symptoms include fecal incontinence, decreased urge to defecate, inability to distinguish between gas and feces, and mucus discharge with pruritus ani. Bleeding often originates from a solitary rectal ulcer or localized proctitis of the involved bowel segment (41). Intussusception is seen in as many as one-third of women with defecatory dysfunction and other symptoms, such as constipation, rectal pain, and fecal incontinence (42). It has also been seen in 29% of asymptomatic patients (43). The intussusception rarely develops into total rectal prolapse (44).
Functional Bowel Disorders Functional bowel disorders, as defined by the Rome III criteria, consist of irritable bowel syndrome, functional bloating, functional constipation, functional diarrhea, and unspecified functional bowel disorders. In this section we will focus primarily on irritable bowel syndrome (45).