A rectocele is a form of pelvic organ prolapse that occurs when the tissues and muscles that hold the end of the large intestine (rectum) in place are stretched or weakened. A rectocele occurs when part of the rectum sags into the vagina. Rectoceles occur because weakness in the normal support system between the vagina and the rectum allow the rectum to bulge outward. The skin of the vagina can stretch very much, which is why these bulges can sometimes be seen or felt well beyond the opening of the vagina. 

The common Causes of Rectocele include:
--Vaginal (normal) childbirth.
--Chronic constipation.
--Advancing age, as older women are more prone to rectocele.
--Pelvic surgery.
--Straining to pass bowel motions.
--Tearing during childbirth, particularly if the tear extended from the vagina to the anus.
--Hysterectomy