Flatus incontinence

Specialty: Gastrointestinal.

• Inability to retain intestinal gases
• minor anal incontinence
• involuntary gas escape

Why it occurs

• Isolated dysfunction of the internal anal sphincter (smooth muscle with continuous involuntary basal tone) secondary to obstetric trauma, surgery for anal fistulas or hemorrhoids
• Diabetic or demyelinating pudendal neuropathy with progressive denervation of the sphincter
• Physiological aging with senile atrophy of anal smooth muscle fibers
• Irritable bowel syndrome of diarrheal type with severe meteorism that exceeds the closing pressure of the anal canal
• Post-radiation rectitis with loss of compliance and rectal capacitance (rigid rectum that cannot act as a gas reservoir).

Initial workup

Dectal examination with measurement of anal tone at rest (mainly evaluates the internal anal sphincter) and voluntary contraction tone (evaluates the external anal sphincter and the puborectalis muscle) | High-resolution anorectal manometry (key study to quantify resting pressures, maximum contraction and rectal sensitivity threshold) | 360-degree endoanal ultrasound (to document structural integrity or scar disruption of the internal and external sphincters) | Dynamic pelvic MRI (to evaluate the descent of the perineum and the anatomy of the levator ani muscles).

Standard management

• Soluble fiber supplements — psyllium or methylcellulose 5-10 g per day to increase the consistency of stools; Well-formed stools stimulate a better anal closure reflex and reduce gas leakage
• Loperamide — 1-2 mg per day at low doses if associated with soft stools to increase the resting tone of the internal anal sphincter
• Amitriptyline or tricyclic antidepressants at low doses — 10 mg at night, useful to modulate rectal hypersensitivity and reduce defecation frequency
• Biofeedback training (rectal biofeedback to strengthen the external anal sphincter muscles and improve the perception of gas filling).