Anal sphincter defect

What is an anal sphincter defect?

An anal sphincter defect is damage or insufficiency of the internal and/or external anal sphincter muscle that interferes with the normal closing function of the anal canal (Figure 1). It may be structural (tear, scar tissue) or functional (innervation disorders) and most often occurs as a result of birth trauma, surgical procedures or injuries.

What are the symptoms of an anal sphincter defect?

Symptom severity depends on the extent of the damage; however, in most cases at least one of the following is characteristic:

• fecal incontinence (partial or complete);
• flatus incontinence;
• urgent need to defecate and inability to hold bowel movements;
• a feeling of uncleanliness or soiling after defecation;
• discomfort in the anal area or skin irritation.

What contributes to the development of a structural anal sphincter defect?

Main risk factors:

• birth trauma (especially grade III–IV perineal tears);
• instrumental deliveries (vacuum, forceps);
• anorectal operations (for example, fistula treatment);
• injuries in the pelvic or perineal region.

How is an anal sphincter defect diagnosed?

Diagnosis is based on clinical assessment (symptom assessment, physical examination) and specific investigations – transrectal ultrasonography (to assess structural defects) and sphincter manometry (to assess sphincter function) are performed.

What complications can an anal sphincter defect cause?

An untreated defect may cause:

• progressive fecal incontinence;
• social isolation and impairment of quality of life;
• dermatitis and skin damage in the anal area;
• psychological problems (anxiety, depression);
• progressive pelvic floor dysfunction.

What is the treatment of an anal sphincter defect?

Treatment is individual and depends on the severity of the damage, but it mainly includes three principal approaches:

• conservative therapy – dietary correction, medications, pelvic floor physiotherapy;
• minimally invasive methods – sphincter stimulation, injections (fillers);
• surgical treatment – sphincteroplasty (reconstruction of the damaged muscle), creation of a stoma (in severe and irreversible cases).

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