Evaluation of anal incontinence: minimal approach, maximal effectiveness

Abstract

Anal incontinence is a symptom represented by the impaired ability to control the elimination of gas and stool, with an estimated incidence of 2.2 to 7.1% of the population. These numbers likely under-represent the true prevalence because physicians and patients are reluctant to discuss this problem. Evaluation of the patient with anal incontinence requires a fundamental knowledge of the etiologic factors. Careful history and physical examination is essential in every patient and can identify the cause of most cases of incontinence. Incontinence scoring systems are tools that provide objective data regarding the severity and quality of anal incontinence. Supplemental special tests for evaluating incontinence should be aimed at achieving three goals: (1) provide additional and confirmatory information regarding the diagnosis and cause of incontinence; (2) select appropriate treatment; and (3) predict treatment outcome. Numerous studies to evaluate anal incontinence exist; however, the most useful tests to achieve these goals are anal manometry, pudendal nerve terminal motor latency, and anal endosonography, because these studies can identify physiologic, neurologic, and anatomic abnormalities of the anorectum for which there may be effective treatments.

Keywords: Anal; evaluation; fecal; incontinence.

Figure 1

Pudendal nerve terminal motor latency (PNTML). Tracing (A) shows a normal right and left PNTML with values < 2.0 milliseconds. Tracing (B) shows a delayed PNTML on the left with values of 2.6 and 2.7 milliseconds.

Figure 2

Anal endosonography images showing (A) an intact anal sphincter complex, and (B) an anterior external sphincter defect. ES represents the hyperechoic (white) external anal asphincter. IS represents the hypoechoic (dark) internal anal sphincter. White arrows represent the edges of the anterior external sphincter defect.