Symptoms of internal intussusception overlap with those of rectocele, indeed the 2 conditions can occur together.Patients with solitary rectal ulcer syndrome combined with internal intussusception (as 94% of SRUS patients have) were shown to have altered rectal wall biomechanics compared to patients with internal intussusception alone. The presumed mechanism of the obstructed defecation is by telescoping of the intussusceptum, occluding the rectal lumen during attempted defecation. One study analysed resected rectal wall specimens in patients with obstructed defecation associated with rectal intussusception undergoing stapled trans-anal rectal resection. They reported abnormalities of the enteric nervous system and estrogen receptors. One study concluded that intussusception of the anterior rectal wall shares the same cause as rectocele, namely deficient recto-vaginal ligamentous support. Comorbidities and complications
The following conditions occur more commonly in patients with internal rectal intussusception than in the general population:

Rectocele
Solitary rectal ulcer syndrome. Diagnosis
Unlike external rectal prolapse, internal rectal intussusception is not visible externally, but it may still be diagnosed by digital rectal examination, while the patient strains as if to defecate. Imaging such as a defecating proctogram or dynamic MRI defecography can demonstrate the abnormal folding of the rectal wall. Some have advocated the use of anorectal physiology testing (anorectal manometry). Treatment
Non surgical measures to treat internal intussusception include pelvic floor retraining, a bulking agent (e.g. psyllium), suppositories or enemas to relieve constipation and straining. If there is incontinence (fecal leakage or more severe FI), or paradoxical contraction of the pelvic floor (anismus), then biofeedback retraining is indicated.
Stapled trans-anal rectal resection (STARR)
This operation aims to "remove the anorectal mucosa circumferential and reinforce the anterior anorectal junction wall with the use of a circular stapler". In contrast to other methods, STARR does not correct the descent of the rectum, it removes the redundant tissue. The technique was developed from a similar stapling procedure for prolapsing hemorrhoids. Since, specialized circular staplers have been developed for use in external rectal prolapse and internal rectal intussusception.Complications, sometimes serious, have been reported following STARR,  but the procedure is now considered safe and effective. STARR is  contraindicated in patients with weak sphincters (fecal incontinence and urgency are a possible complication) and with anismus (paradoxical contraction of the pelvic floor during attempted defecation). The operation has been shown to improve rectal sensitivity and decrease rectal volume, the reason thought to create urgency. 90% of patients do not report urgency 12 months after the operation. The anal sphincter may also be stretched during the operation. STARR was compared with biofeedback and found to be more effective at reducing symptoms and improving quality of life. Mucosal prolapse
Rectal mucosal prolapse (mucosal prolapse, anal mucosal prolapse) is a sub-type of rectal prolapse, and refers to abnormal descent of the rectal mucosa through the anus.