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

• Treatment failure of constipation is suspected if any 1 of the following are present during the last 1-2 weeks:
  • No improvement in stool consistency on current treatment
  • Insufficient improvement of other signs and symptoms of chronic constipation on current treatment
  • Need to strain on most occasions or straining is getting worse
  • Inadequate bowel movements most of the time as reported by patient and <3 days/week complete bowel movements
  • Poor tolerance to current therapy making the relief provided unacceptable 
• 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 biofeedback therapy
  • 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 functional defecatory disorders
  • Behavioral treatments including psychotherapy may improve patient’s quality of life and coping in functional constipation but further studies are needed to determine its specific effect on constipation
• 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       
  • May be performed with anorectal manometry in patients with suggestive obstructed defecation  
• This test reveals structural posterior compartment 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 
• Barium defecography is considered in assessing structural rectal abnormalities and posterior compartment disorders 
• Magnetic resonance (MR) defecography can evaluate all pelvic compartments in patients in whom multicompartmental structural defects are suspected 
• Echodefecography or MR 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