constipation%20in%20adults%20-%20chronic%20functional
CONSTIPATION IN ADULTS - CHRONIC FUNCTIONAL
Constipation is an unsatisfactory defecation distinguished by difficult stool passage, infrequent stools or both.
Difficult stool passage may include straining, feeling of difficulty in passing stool, incomplete evacuation, lumpy/hard stools, prolonged time to defecate, need for manual maneuver to pass stool, abdominal discomfort and feeling of anorectal blockade.
Chronic constipation is considered when symptoms of constipation have existed ≥3 months.
Symptoms of chronic constipation may be due to dysfunction of intestinal motility, visceral sensitivity, anorectal musculature or the enteric nervous system.

Constipation%20in%20adults%20-%20chronic%20functional Management

Further Evaluation

  • If patient with chronic constipation does not respond to conventional therapy, he should be evaluated for: 
    • Slow transit constipation
    • Pelvic floor dysfunction
    • Other evacuation disorders or disorders of anorectal musculature  
  • Patient may also be referred for psychological evaluation for possible behavioral, biofeedback, or psychotherapy
    • Biofeedback is a technique wherein patients are taught to relax their pelvic floor muscles while straining; it is the cornerstone for pelvic floor dysfunction management and may be considered in patients with defecatory disorders
  • Chronic constipation is refractory when symptoms persist after a 4-week trial of medical therapy to each drug or a 3-month trial of pelvic floor behavioral therapy

Specialized Physiologic Tests

Anorectal Manometry with Balloon Expulsion Test (BET)

  • Provides measurement of internal and external anal sphincter pressure, relaxation of the internal anal sphincter during rectal distension and straining and rectal sensation to distension in patients with chronic constipation resistant to medical therapy
  • This may be the test of choice for outlet obstruction, pelvic floor dysfunction and for excluding Hirschsprung’s disease and psychogenic megacolon, may even be considered before a trial of laxatives in patients with a strong suspicion of pelvic floor dysfunction  
    • An abnormal test result confirms a defecatory disorder 
  • Recommended for patients unresponsive to a high-fiber diet and/or simple laxatives 
    • Patients with normal findings may be treated with a secretagogue or prokinetic agent

Colon Transit Studies

  • Radiopaque markers are used to measure GI transit
  • Considered when an outlet obstruction is not demonstrated by clinical and proctologic exams  
  • Performed on patients with symptoms unresponsive to laxatives or 1st-line pharmacological treatment or if anorectal test does not demonstrate a defecatory disorder 
    • Prokinetic agents can be used for slow transit constipation 
  • Other approaches include scintigraphy and a wireless pH-pressure capsule which can measure both gastric emptying time and small intestinal transit

Defecography

  • May be done if results with anorectal manometry and rectal balloon expulsion are inconclusive or if patients have persistent symptoms after biofeedback therapy (if not yet performed) 
    • May be performed with anorectal manometry in patients with suggestive obstructed defecation  
  • This test reveals structural abnormalities (eg rectocele and intussusceptions) and evaluates mobility of the pelvic floor and degree of rectal emptying 
    • Pelvic floor dysfunction is diagnosed by the observation of insufficient descent of the perineum and less-than-normal change in the anorectal angle 
  • Echodefecography or magnetic resonance defecography may be preferred over videodefecography in order to avoid ionizing radiation
  • This test is operator dependent and has poor reliability 

Electromyography of Anal Sphincter  

  • Used in diagnosing presence of paradoxical contraction of puborectalis muscle

Hydrogen Breath Test  

  • Evaluates orocecal transit time in patients with colonic inertia
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