Anal incontinence is a symptom represented by the impaired ability to control the elimination of gas and stool, with an estimated incidence of 2. 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.
Maintenance of the basal tone in the internal anal sphincter IAS is critical for rectoanal continence. Systematic studies examining the nature of the INT in different species have identified nitric oxide NO as the major inhibitory neurotransmitter. However, other mediators such as vasoactive intestinal polypeptide VIP , ATP, and carbon monoxide CO may also play species-specific role under certain experimental conditions. Measurements of the intraluminal pressures in the IAS along with the force of the isolated IAS tissues are the mainstay in the basic studies for the molecular mechanisms underlying the basal tone and in the nature of the INT. The identification of NO as the inhibitory neurotransmitter has led to major advances in the diagnosis and treatment of a number of rectoanal motility disorders associated with the IAS dysfunction.
The internal anal sphincter , IAS , or sphincter ani internus is a ring of smooth muscle that surrounds about 2. Its action is entirely involuntary , and it is in a state of continuous maximal contraction. It helps the Sphincter ani externus to occlude the anal aperture and aids in the expulsion of the feces. Sympathetic fibers from the superior rectal and hypogastric plexuses stimulate and maintain internal anal sphincter contraction.
Fecal incontinence is the inability to control your bowels. When you feel the urge to have a bowel movement, you may not be able to hold it until you can get to a toilet. Or stool may leak from the rectum unexpectedly.