A rectal stricture (rectal stenosis) 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 (12 mm diameter) or a rigid sigmoidoscope (19 mm diameter) 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 (at the level of the external anal sphincter and the puborectalis muscle). 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 (pectinate 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 (anal stenosis) 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 (clinically silent stricture), 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 (chronic difficulty during defecation) which may sometimes turn into obstipation (severe constipation with inability to pass stool or gas), or acute bowel obstruction. Incomplete evacuation of stool. Increased frequency of bowel movements. Defecation urgency. Reduction in caliber (diameter) of stool ("pencil-thin stools"). Change in stool consistency. Anorectal bleeding. Tenesmus. Abdominal distention and abdominal discomfort (left lower quadrant) that is usually worse after eating. Anal pain. Hematochezia. Fecal incontinence (due to overflow diarrhea). Tenesmus. Fecal impaction.
Diagnosis The first step is exclusion of malignant causes. This may involve tissue biopsy, endorectal ultrasound, computed tomography, and magnetic resonance imaging. The next step is assessment of the stricture. The distance from the anal verge, the diameter of the narrowest point of the stricture, and the longitudinal length are ascertained. The degree of narrowing can be assessed with a water-soluble contrast enema.
Classification Rectal strictures are usually classified as benign or malignant (associated with cancer).
Benign Benign rectal strictures can be further subcategorized as primary (caused by diseases) and secondary (caused by complication of surgery). 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 (The most common type of benign rectal stricture.) Inflammatory bowel disease (e.g., Crohn's disease or ulcerative colitis). 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 (e.g., lymphogranuloma venereum). Tuberculosis. Actinomycosis. Solitary rectal ulcer syndrome.
Malignant Acute bowel obstruction is a common presenting manifestation of colorectal cancer which is locally advanced. Malignant strictures may also develop in the context of inflammatory bowel disease. Treatment for malignant strictures is ideally resection (surgical removal) with or without radiotherapy. If resection is not possible or not sensible, symptoms of the stricture may be palliated with radiotherapy, stents, or debulking. Possible malignant processes which may cause rectal stricture include:
Primary rectal cancer. Recurrent rectal cancer. Ovarian cancer. Prostate cancer. Lymphoma. Sarcoma.
Causes The narrowing may be because of an intrinsic process occurring within the lumen of the rectum (luminal), within the wall of the rectum (mural), or it can be due to an extrinsic process that is compressing the rectum from the outside (extramural). In the case of external compression of the bowel, the term pseudostricture may be used. 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 (usually performed after right‐sided colon cancer and Crohn's disease).
… excerpt ends here. Continue reading the full article.
