Rectal Prolapse/Solitary Rectal
Abnormal puborectalis muscle contraction and rectal wall prolapse or intussusception are often implicated in the pathogenesis of solitary rectal ulcer syndrome, a benign condition found mostly in adults. Prolapse ranges from internal to external; the term intussusception is appropriate if it is circumferential. Complete rectal prolapse is a clinical diagnosis and generally needs surgical correction. Whether this condition is one syndrome or encompasses a number of disorders is conjecture. Diffuse pelvic floor weakness involving genitourinary structures is found in some women. Chronic constipation, evacuation abnormalities, and rectal prolapse are typical presentations. Confusing the issue, some authors find rectal bleeding to be common, but others believe it is an uncommon finding.
Pressure necrosis and mucosal injury during rectal prolapse and intermittent intussusception appear to play a role, although the pathophysiology is probably multifactorial. Typical histopathologic findings consist of focal mucosal distortion, muscularis mucosa proliferation, and obliteration of lamina propria. An ulcer, accompanied by granulation tissue, is usually located anterior in the rectum but at times extends circumferentially. Sigmoidoscopy is generally noncontributory in these patients, aside from providing a biopsy and excluding other abnormalities. In some patients manometry reveals decreased external sphincter tone during straining, a nonspecific finding.
Biopsy in patients believed to suffer from solitary rectal ulcer syndrome revealed a solitary ulcer in 78%,multiple ulcers in 11%, granular proctitis in 7%, and rectal inflammation in 4%; although voiding proctography missed some ulcers, it identified rectal intussusception in 41%, rectoanal intussusception in 26%, external rectal prolapse in 22%, and mucosal prolapse in 30%. Only one patient had a rectocele. In a majority of patients videoproctography showed that the ulcer wall was first to invaginate.
Solitary rectal ulcer syndrome and an inflammatory cloacogenic polyp have similar histopathologic findings; both are located anterior in the rectum and both tend to be associated with rectal prolapse. Previous therapy for intractable symptoms included rectocolic resection, a procedure rarely performed today.After elastic binding for rectal mucosal prolapse, follow-up voiding proctography revealed prolapse remission in most patients.
A double-contrast barium enema, with emphasis on the anterior rectal wall, is useful to detectan ulcer and the sequelae of inflammation, but an evacuation study is necessary to evaluate functional abnormalities. Imaging is also often requested prior to surgical repair to evaluate the rest of the large bowel. In spite of its name, solitary rectal ulcer syndrome does not always present with an ulcer, nor is it always solitary. A common imaging appearance is that of nodularity or an anterior rectal wall irregular polyp. Similar findings are seen with an inflammatory cloacogenic polyp; some mimic a rectal adenocarcinoma. Voiding videoproctography is the imaging modality of choice for suspected rectal prolapse. Prolapse originates in the midrectum as an intussusception varying in length. Proctography reveals rectal mucosal prolapse as a soft tissue bulge into the rectal lumen, more evident during straining and evacuation than during rest. Mucosal prolapse is morecommon than intussusception (204).Associated other abnormalities are common and include rectocele, perineal descent syndrome, puborectalis muscle syndrome, and levator ani diastasis, the latter identified with dynamic CT.
At times endorectal US is helpful. Ultrasonography reveals an inhomogeneous and thickened submucosa in the internal and external sphincter regions; the ratio of external to internal anal sphincter thickness is reduced in these patients and muscle hypertrophy identified by US appears useful in some in suggestingthe diagnosis.
This is radiology images of Rectal prolapse. A: Initial lateral view is unremarkable. B: Prolapse becomes evident with early straining. Further straining reveals marked prolapse (C, cursor), also identified on a frontal view (D).