Definition
A rectal stricture, or stenosis, is a pathologic narrowing or constriction involving the lumen of the rectum. This narrowing can be the result of an intrinsic process that is occurring within the lumen or wall of the rectum, or it can be secondary to an extrinsic process compressing the rectum. A “clinically relevant” rectal stricture is one that is symptomatic and not easily defined by measurement of the diameter. However, the condition frequently has been illustrated in terms of the inability to traverse the affected cross-section of rectum with either a rigid proctoscope (12 mm diameter) or a rigid sigmoidoscope (19 mm diameter).
Presentation and Diagnosis
Symptomatic rectal strictures cause obstructive symptoms such as a gradual change in stool caliber or consistency, anorectal bleeding, tenesmus, or abdominal distention and discomfort that is often exacerbated by eating. Some symptomatic rectal strictures that are not treated will eventually cause a complete large bowel obstruction, especially those associated with inflammatory bowel disease (IBD), malignancy, and radiation-induced proctitis.
The diagnosis of a rectal stricture is based on history, physical examination, and, occasionally, imaging findings. The degree of a stenosis is best imaged with a water-soluble contrast enema. Computed tomography and magnetic resonance imaging, with or without rectal contrast enhancement, can be helpful in assessing other segments of the alimentary tract or the peritoneal cavity for conditions such as IBD and cancer.
Etiology
Strictures of the rectum may develop as a result of multiple causes that can be broadly categorized as benign and malignant. These causes are listed in Table 20-1 . Management depends on the cause of the stricture, its distance from the anal verge, and the degree of stenosis.
| Benign | Malignant |
|---|---|
| Anastomotic stricture | Primary rectal cancer |
| Inflammatory bowel disease (e.g., Crohn disease/ulcerative colitis) | Recurrent rectal cancer |
| Radiation | Ovarian cancer |
| Ischemia | Prostate cancer |
| Penetrating injury/foreign body trauma | Lymphoma |
| Caustic injury | Sarcoma |
| Endometriosis | |
| Pelvic abscess | |
| Sexually transmitted infections (e.g., lymphogranuloma venereum) | |
| Tuberculosis |
Benign Rectal Strictures
Although a variety of benign diseases can produce a rectal stricture, most benign strictures are due to an ischemic colorectal anastomosis or IBD. Benign rectal strictures do not need to be treated unless they are symptomatic, at which point several options are available, depending on the nature and severity of the stricture ( Fig. 20-1 ). Patients may be referred to a colorectal surgeon because an unexpected stricture is discovered during a colonoscopy. It is vital that the surgeon understand the difference between a stricture that requires treatment and a stricture that has been found incidentally. All strictures require assessment before it is safe to recommend observation. The first step in the assessment is to exclude malignancy. Multiple biopsies, as well as imaging with endorectal ultrasound, computed tomography, and magnetic resonance imaging, are usually required to exclude cancer. All strictures should be described in terms of their diameter, their distance from the anal verge, and their length, because shorter strictures are more amenable to endoscopic dilatation than are longer benign strictures, which are more likely to require either diversion or resection.
