Rectal stricture
A rectal stricture is a chronic and abnormal narrowing or constriction of the lumen of the rectum which presents a partial or complete obstruction to the movement of bowel contents. A rectal stricture is located deeper inside the body compared to an anal stricture. Sometimes other terms with wider meaning are used, such as anorectal stricture, colorectal stricture or rectosigmoid stricture.
Definition
Rectal stricture has been defined as the inability to pass a rigid proctoscope or a rigid sigmoidoscope through the affected cross-section of rectum. If the rectal stricture is accessible during digital rectal examination, a rectal stricture may be defined as narrowing to less than one-finger breadth.Anal stricture versus rectal stricture
Anal strictures are usually located at the anal verge in a narrow band, but sometimes they involve the entire length of the anal canal. Surgeons and anatomists have different definitions of the anal canal. Surgically and clinically, the anal canal is usually defined as the zone from the anal verge to the anorectal ring. The anorectal ring is easy to identify when patients are asked to squeeze during digital rectal examination. Anatomically, the anal canal is defined as the zone from the anal verge to the dentate line. This is a line formed by the lower ends of the anal columns and represents the embryological junction between the hindgut and the proctodeum.Both rectal stricture and anal stricture are types of colonic stricture. They both can also be more widely categorized as gastrointestinal strictures. However, rectal strictures behave differently to colonic strictures because of the proximity of the rectum to the anal canal and pelvic organs, and because of different blood supply.
Signs and symptoms
There may be no symptoms, or only minor symptoms, but may get worse over time. On the other hand, acute bowel obstruction may develop as the first major sign of a stricture. This may be the case with malignant strictures, and the condition may be a medical emergency which requires urgent treatment in order to avoid serious complications such as bowel perforation. When symptoms are caused, the term "clinically relevant rectal stricture" is used. Possible symptoms include:- Obstructed defecation which may sometimes turn into obstipation, or acute bowel obstruction.
- Incomplete evacuation of stool.
- Increased frequency of bowel movements.
- Defecation urgency.
- Reduction in caliber of stool.
- Change in stool consistency.
- Anorectal bleeding.
- Tenesmus.
- Abdominal distention and abdominal discomfort that is usually worse after eating.
- Anal pain.
- Hematochezia.
- Fecal incontinence.
- Tenesmus.
- Fecal impaction.
Diagnosis
Classification
Rectal strictures are usually classified as benign or malignant.Benign
Benign rectal strictures can be further subcategorized as primary and secondary. Secondary strictures very often occur at the site of a previous surgical anastomosis. Primary strictures have various causes, including different inflammatory disease processes. Causes of benign strictures include:- Stricture at the site of surgical anastomosis
- Inflammatory bowel disease.
- After submucosal endoscopic dissection.
- Radiotherapy.
- Ischemia.
- Penetrating injury.
- Foreign body trauma, e.g. chronic use of suppositories.
- Caustic injury.
- Endometriosis.
- Pelvic abscess.
- perianal fistula.
- Sexually transmitted infections.
- Tuberculosis.
- Actinomycosis.
- Solitary rectal ulcer syndrome.
Malignant
- Primary rectal cancer.
- Recurrent rectal cancer.
- Ovarian cancer.
- Prostate cancer.
- Lymphoma.
- Sarcoma.
Causes
According to one review of a total of 730 cases, those which formed after anastomosis represented 74% of all reported benign rectal strictures. The next most common cause of benign rectal stricture was inflammatory bowel disease, accounting for 20% of all cases. This means all other causes of rectal stricture are, by comparison, rare.
Anastomosis
Rectal stricture is reported to develop after colorectal resection at a rate of 3-30%. Such strictures mostly form after resection due to rectal cancer with colorectal or coloanal anastomosis. Stricture is also possible as a complication following resection because of diverticular disease. According to some reports, rectal strictures are more likely following stapled anastomosis compared to hand sutured anastomosis. However, a Cochrane review found no significant difference in the rate of rectal stricture between hand sewn and stapled ileocolic anastomosis.Inflammatory bowel disease
Inflammatory bowel diseases include ulcerative colitis, which affects only the colon, and Crohn's disease, which may affect any section of the gastrointestinal tract. The relapsing-remitting, chronic inflammation in the bowel wall can lead to the development of colonic strictures, including rectal strictures. Rectal strictures are more common in Crohn's disease than in ulcerative colitis. There is a risk of malignancy developing at the site of stricture; therefore, tissue biopsy of strictures is carried out in order to check for dysplasia or malignancy.Trauma
Stricture may occur following trauma such as caustic burns caused by chemical agents. If they cause inflammation, chronic use of suppositories may cause rectal stricture, but overall this is a safe method of drug delivery.Thermal burns are possible if hot water enemas are attempted by patients or practitioners of alternative medicine in the belief that they will provide a stronger stimulus for evacuation of stool. The rectal mucosa is vulnerable to thermal burns in such cases because it is sensitive only to distension and not to thermal stimuli. Usually a burn of the rectal wall heals after 2–3 weeks without permanent stricture. Such burns may be treated with bowel resting, antibiotics, stool softeners, liquid diet and steroid suppository to reduce inflammation. Sometimes thermal burns progress to chronic stricture.
Radiation
The rectum is very close to the prostate in males and the uterus and cervix in females, and therefore it frequently receives radiation during radiotherapy for cancers in the pelvic region. Radiation proctitis usually appears after several months of treatment, and is characterized by rectal bleeding or obstructed defecation secondary to the formation of strictures. Such rectal strictures are usually located in the proximal rectum, and are one of the most common features of late radiation damage. The mechanism of stricture formation is obliterative endarteritis, lymphatic dilation, and tissue ischemia and necrosis. Then there is collagen deposition and fibrosis in the submucosal layer. They are often associated with a fistula. Post-irradiation strictures may cause symptoms such as diarrhea, tenesmus, narrow feces, abdominal pain, and vomiting. The risk of intestinal obstruction due to strictures in patients receiving radiotherapy in the pelvis is reported as 1–15%.Infection
s may sometimes cause rectal strictures in persons who engage in anoreceptive sex. Lymphogranuloma venereum usually affects the genital mucosa. However, it may rarely present as the anorectal variant, termed "lymphogranuloma venereum proctitis". Lymph nodes are enlarged and suppurative. The condition is similar to Crohn's disease with rectal stricture formation, bowel perforation and fistulae. In one report, herpes simplex virus 2 was implicated as the cause of a rectal stricture. Rarely, rectal stricture may develop in actinomycosis infection.Other
If a foreign body becomes stuck there is reactive inflammation and fibrosis, which eventually may lead to the formation of a stricture. In endometriosis, if ectopic endometrial tissue is present in the rectal wall it may cause rectal stricture. Solitary rectal ulcer syndrome may also sometimes be associated with rectal stricture.Rectal stricture may sometimes be a complication of surgical procedures other than anastomosis. For example, endoscopic submucosal dissection, which is a minimally invasive treatment for colorectal cancer, may rarely cause development of a rectal stricture. Other surgical procedures which may cause the development of a stricture include ventral rectopexy, Delorme's procedure, and hemorrhoidectomy.