A rectocele results from a tear in the rectovaginal septum (which is normally a tough fibrous sheet like divider between the rectum and vagina). Rectal tissue bulges trough this tear, into the vagina, as a hernia. There are two main causes of this tear: childbirth and hysterectomy.
Mild cases may simply produce a sense of pressure or protrusion within the vagina, and the occasional feeling that the rectum has not been completely emptied after a bowel movement. Moderate cases may involve difficulty passing stool (because the attempt to evacuate pushes the stool into the rectocele instead of out through the anus), discomfort or pain during evacuation or intercourse, constipation, and a general sensation that something is "falling down" or "falling out" within the pelvis. Severe cases may cause vaginal bleeding, intermittent fecal incontinence, or even the prolapse of the bulge through the mouth of the vagina, or rectal prolapse through the anus.
It can be caused by many factors, but the most common is childbirth, especially with babies over nine pounds in weight, or rapid births. The use of forceps is more likely a marker for the vaginal injury, than a direct cause of the tear. Episiotomy or lower vaginal tears play little role in the formation of a cystocele. The risk increases with the number of vaginal births, although it can also happen in women who have never borne a child.
A hysterectomy or other pelvic surgery can be a cause, as can chronic constipation and straining to pass bowel movements. It is more common in older women than in younger ones; estrogen which helps to keep the pelvic tissues elastic decreases after menopause. Another cause which is sometimes overlooked in younger women is sexual abuse during childhood.
Treatment depends on the severity of the problem, and may include changes in diet (increase in fiber and water intake), pelvic floor exercises such as Kegel exercises, use of stool softeners, hormone replacement therapy for post-menopausal women, insertion of a pessary into the vagina, and various forms of surgery (usually posterior colporrhaphy - the suturing of vaginal tissue). More recent developments in surgery are directed at repairs to the rectovaginal septum, than simple excision or plication of vaginal skin, which provides no support. Both gynecologists and colorectal surgeons can address this problem.