Essentially, rectal prolapses may be:
full thickness (complete), where all the layers of the rectal wall prolapse, or involve the mucosal layer only (partial)
external  if they protrude from the anus and are visible externally, or internal if they do not
circumferential, where the whole circumference of the rectal wall prolapse, or segmental if only parts of the circumference of the rectal wall prolapse
present at rest, or occurring during straining.External (complete) rectal prolapse (rectal procidentia, full thickness rectal prolapse, external rectal prolapse) is
a full thickness, circumferential, true intussusception of the rectal wall which protrudes from the anus and is visible externally.Internal rectal intussusception (occult rectal prolapse, internal procidentia) can be defined as a funnel shaped infolding of the upper rectal (or lower sigmoid) wall that can occur during defecation. This infolding is perhaps best visualised as folding a sock inside out, creating "a tube within a tube". Another definition is "where the rectum collapses but does not exit the anus". Many sources differentiate between internal rectal intussusception and mucosal prolapse, implying that the former is a full thickness prolapse of rectal wall. However, a publication by the American Society of Colon and Rectal Surgeons stated that internal rectal intussusception involved the mucosal and submucosal layers separating from the underlying muscularis mucosa layer attachments, resulting in the separated portion of rectal lining "sliding" down. This may signify that authors use the terms internal rectal prolapse and internal mucosal prolapse to describe the same phenomena.
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. Treatment
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.