chronically prolapsed rectal tissue may undergo pathological changes such as thickening, ulceration and bleeding. if the prolapse becomes trapped externally outside the anal sphincters, it may become strangulated and there is a risk of perforation. this may require an urgent surgical operation if the prolapse cannot be manually reduced. applying granulated sugar on the exposed rectal tissue can reduce the edema (swelling) and facilitate this. cause micrograph showing a rectal wall with changes seen in rectal prolapse. there is a marked increase of fibrous tissue in the submucosa and fibrous tissue +/- smooth muscle hyperplasia in the lamina propria. h&e stain the precise cause is unknown, and has been much debated. in 1912 moschcowitz proposed that rectal prolapse was a sliding hernia through a pelvic fascial defect. this theory was based on the observation that rectal prolapse patients have a mobile and unsupported pelvic floor, and a hernia sac of peritoneum from the pouch of douglas and rectal wall can be seen. other adjacent structures can sometimes be seen in addition to the rectal prolapse. although a pouch of douglas hernia, originating in the cul de sac of douglas, may protrude from the anus (via the anterior rectal wall), this is a different situation from rectal prolapse. shortly after the invention of defecography, in 1968 broden and snellman used cinedefecography to show that rectal prolapse begins as a circumferential intussusception of the rectum, which slowly increases over time. the leading edge of the intussusceptum may be located at 6–8 cm or at 15–18 cm from the anal verge. this proved an older theory from the 18th century by john hunter and albrecht von haller that this condition is essentially a full-thickness rectal intussusception, beginning about 3 inches above the dentate line and protruding externally. since most patients with rectal prolapse have a long history of constipation, it is thought that prolonged, excessive and repetitive straining during defecation may predispose to rectal prolapse. since rectal prolapse itself causes functional obstruction, more straining may result from a small prolapse, with increasing damage to the anatomy. this excessive straining may be due to predisposing pelvic floor dysfunction (e.g. obstructed defecation) and anatomical factors: abnormally low descent of the peritoneum covering the anterior rectal wall poor posterior rectal fixation, resulting in loss of posterior fixation of the rectum to the sacral curve loss of the normal horizontal position of the rectum with lengthening (redundant rectosigmoid) and downward displacement of the sigmoid and rectum long rectal mesentery a deep cul-de-sac levator diastasis a patulous, weak anal sphincter some authors question whether these abnormalities are the cause, or secondary to the prolapse. other predisposing factors/associated conditions include: pregnancy (although 35% of women who develop rectal prolapse are nulliparous) (have never given birth) previous surgery (30-50% of females with the condition underwent previous gynecological surgery) pelvic neuropathies and neurological disease high gastrointestinal helminth loads (e.g. whipworm) copd cystic fibrosis the association with uterine prolapse (10-25%) and cystocele (35%) may suggest that there is some underlying abnormality of the pelvic floor that affects multiple pelvic organs. proximal bilateral pudendal neuropathy has been demonstrated in patients with rectal prolapse who have fecal incontinence. this finding was shown to be absent in healthy subjects, and may be the cause of denervation-related atrophy of the external anal sphincter. some authors suggest that pudendal nerve damage is the cause for pelvic floor and anal sphincter weakening, and may be the underlying cause of a spectrum of pelvic floor disorders. sphincter function in rectal prolapse is almost always reduced. this may be the result of direct sphincter injury by chronic stretching of the prolapsing rectum. alternatively, the intussuscepting rectum may lead to chronic stimulation of the rectoanal inhibitory reflex (rair - contraction of the external anal sphincter in response to stool in the rectum). the rair was shown to be absent or blunted. squeeze (maximum voluntary contraction) pressures may be affected as well as the resting tone. this is most likely a denervation injury to the external anal sphincter. the assumed mechanism of fecal incontinence in rectal prolapse is by the chronic stretch and trauma to the anal sphincters and the presence of a direct conduit (the intussusceptum) connecting rectum to the external environment which is not guarded by the sphincters. the assumed mechanism of obstructed defecation is by disruption to the rectum and anal canal's ability to contract and fully evacuate rectal contents. the intussusceptum itself may mechanically obstruct the rectoanal lumen, creating a blockage that straining, anismus and colonic dysmotility exacerbate. some believe that internal rectal intussusception represents the initial form of a progressive spectrum of disorders the extreme of which is external rectal prolapse. the intermediary stages would be gradually increasing sizes of intussusception. however, internal intussusception rarely progresses to external rectal prolapse. the factors that result in a patient progressing from internal intussusception to a full thickness rectal prolapse remain unknown. defecography studies demonstrated that degrees of internal intussusception are present in 40% of asymptomatic subjects, raising the possibility that it represents a normal variant in some, and may predispose patients to develop symptoms, or exacerbate other problems. conservative surgery is thought to be the only option to potentially cure a complete rectal prolapse. for people with medical problems that make them unfit for surgery, and those who have minimal symptoms, conservative measures may be beneficial. dietary adjustments, including increasing dietary fiber may be beneficial to reduce constipation, and thereby reduce straining. a bulk forming agent (e.g. psyllium) or stool softener can also reduce constipation. surgical surgery is often required to prevent further damage to the anal sphincters. the goals of surgery are to restore the normal anatomy and to minimize symptoms. there is no globally agreed consensus as to which procedures are more effective, and there have been over 50 different operations described. surgical approaches in rectal prolapse can be either perineal or abdominal. a perineal approach (or trans-perineal) refers to surgical access to the rectum and sigmoid colon via an incision around the anus and perineum (the area between the genitals and the anus). abdominal approach (trans-abdominal approach) involves the surgeon cutting into the abdomen and gaining surgical access to the pelvic cavity. procedures for rectal prolapse may involve fixation of the bowel (rectopexy), or resection (a portion removed), or both. trans-anal (endo-anal) procedures are also described where access to the internal rectum is gained through the anus itself. abdominal procedures are associated with lower risk of postoperative recurrence of the prolapse, compared with perineal procedures (6.1% vs 16.3% in patients who are younger than 65 years of age at the time of surgery). abdominal procedures the abdominal approach carries a small risk of impotence in males (e.g. 1-2% in abdominal rectopexy). abdominal operations may be open or laparoscopic (keyhole surgery). laparoscopic procedures recovery time following laparoscopic surgery is shorter and less painful than following traditional abdominal surgery. instead of opening the pelvic cavity with a wide incision (laparotomy), a laparoscope (a thin, lighted tube) and surgical instruments are inserted into the pelvic cavity via small incisions. rectopexy and anterior resection have been performed laparoscopically with good results. perineal procedures the perineal approach generally results in less post-operative pain and complications, and a reduced length of hospital stay. these procedures generally carry a higher recurrence rate and poorer functional outcome. the perineal procedures include perineal rectosigmoidectomy and delorme repair. elderly, or other medically high-risk patients are usually treated by perineal procedures, as they can be performed under a regional anesthetic, or even local anesthetic with intravenous sedation, thus avoid the risks of a general anesthetic. alternatively, perineal procedures may be selected to reduce risk of nerve damage, for example in young male patients for whom sexual dysfunction may be a major concern. perineal rectosigmoidectomy the goal of perineal rectosigmoidectomy is to resect or remove the redundant bowel. this is done through the perineum. the lower rectum is anchored to the sacrum through fibrosis in order to prevent future prolapse. the full thickness of the rectal wall is incised at a level just above the dentate line. redundant rectal and sigmoid wall is removed and the new edge of colon is reconnected (anastomosed) with the anal canal with stitches or staples. this procedure may be combined with levatorplasty, to tighten the pelvic muscles. a combined a perineal proctosigmoidectomy with anterior levatorplasty is also called an altemeier procedure. levatorplasty is performed to correct levator diastasis which is commonly associated with rectal prolapse. perineal rectosigmoidectomy was first introduced by mikulicz in 1899, and it remained the preferred treatment in europe for many years. it was popularized by altemeier. the procedure is simple, safe and effective. continence levatorplasty may enhance restoration of continence (2/3 of patients). complications occur in less than 10% of cases, and include pelvic bleeding, pelvic abscess and anastomotic dehiscence (splitting apart of the stitches inside), bleeding or leak at a dehiscence mortality is low. recurrence rates are higher than for abdominal repair, 16-30%, but more recent studies give lower recurrence rates. additional levatorplasty can reduce recurrence rates to 7%. delorme procedure this is a modification of the perineal rectosigmoidectomy, differing in that only the mucosa and submucosa are excised from the prolapsed segment, rather than full thickness resection. the prolapse is exposed if it is not already present, and the mucosal and submucosal layers are stripped from the redundant length of bowel. the muscle layer that is left is plicated (folded) and placed as a buttress above the pelvic floor. the edges of the mucosal are then stitched back together. "mucosal proctectomy" was first discussed by delorme in 1900, now it is becoming more popular again as it has low morbidity and avoids an abdominal incision, while effectively repairing the prolapse. the procedure is ideally suited to those patients with full-thickness prolapse limited to partial circumference (e.g., anterior wall) or less-extensive prolapse (perineal rectosigmoidectomy may be difficult in this situation). fecal incontinence is improved following surgery (40%–75% of patients). post operatively, both mean resting and squeeze pressures were increased. constipation is improved in 50% of cases, but often urgency and tenesmus are created. complications, including infection, urinary retention, bleeding, anastomotic dehiscence (opening of the stitched edges inside), stricture (narrowing of the gut lumen), diarrhea, and fecal impaction occur in 6-32% of cases. mortality occurs in 0–2.5% cases. there is a higher recurrence rate than abdominal approaches (7-26% cases). anal encirclement (thirsch procedure) this procedure can be carried out under local anaesthetic. after reduction of the prolapse, a subcutaneous suture (a stich under the skin) or other material is placed encircling the anus, which is then made taut to prevent further prolapse. placing silver wire around the anus first described by thiersch in 1891. materials used include nylon, silk, silastic rods, silicone, marlex mesh, mersilene mesh, fascia, tendon, and dacron. this operation does not correct the prolapse itself, it merely supplements the anal sphincter, narrowing the anal canal with the aim of preventing the prolapse from becoming external, meaning it remains in the rectum. this goal is achieved in 54-100% cases. complications include breakage of the encirclement material, fecal impaction, sepsis, and erosion into the skin or anal canal. recurrence rates are higher than the other perineal procedures. this procedure is most often used for people who have a severe condition or who have a high risk of adverse effects from general anesthetic, and who may not tolerate other perineal procedures. internal rectal intussusception internal rectal intussusception (rectal intussusception, internal intussusception, internal rectal prolapse, occult rectal prolapse, internal rectal procidentia and rectal invagination) is a medical condition defined as a funnel shaped infolding of the rectal wall that can occur during defecation. this phenomenon was first described in the late 1960s when defecography was first developed and became widespread. degrees of internal intussusception have been demonstrated in 40% of asymptomatic subjects, raising the possibility that it represents a normal variant in some, and may predispose patients to develop symptoms, or exacerbate other problems. symptoms internal intussusception may be asymptomatic, but common symptoms include: fecal leakage sensation of obstructed defecation (tenesmus). pelvic pain. rectal bleeding. recto-rectal intussusceptions may be asymptomatic, apart from mild obstructed defecation. "interrupted defaecation" in the morning is thought by some to be characteristic. recto-anal intussusceptions commonly give more severe symptoms of straining, incomplete evacuation, need for digital evacuation of stool, need for support