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Constipation           See also constipation_rx.pdf    

* Passage of material from the cecum through the colon to the rectum ordinarily takes about 24 hours.
   Defecation involves peristaltic waves, relaxation of the pelvic floor muscles & the external anal sphincter.

Possible mechanisms of constipation include excessive absorption of fluids, impaired evacuation, & slow colonic transit (colonic inertia).  

Possible Causes of chronic constipation:

Diagnostic Approach:

  1. History & physical examination
  2. Lab. tests: CBC, TSH, lytes, calcium, glucose, creatinine, fecal occult blood, barium enema x-ray, sigmoidoscopy or colonoscopy.
  3. Colonic transit test with high-fiber diet & ingestion of markers, then x-ray for several days; anorectal manometry; air or water-filled balloon expulsion test; defecography with artificial stool in the rectum.
    * Colonic Transit Test is studied by giving patients radiopaque markers orally & performing radiographic studies daiy or 5-7 days later.  A total transit time of up to about 70 hours is condidered normal.  

Treatment Options:

Empirical Rx Steps:

  1. Adequate hydration & dietary fiber intake (25-35 g/d), exercise, dedicated time for bowel movements
  2. Processed or synthetic fiber as  Metamucil powder (psyllium), methylcellulose
    Stool softeners as Docusate-Na  (Colace)100-200 mg 1-2x/d, docusate-Ca (Surfak) 240 mg 1-2x/d, mineral oil 15-45 mL/d.  
  3. Osmotic laxatives:
    Mg-sulfate 15-45 mL/d, Mg-citrate 200 mL/d, Fleet Phospha-soda 20-45 mL prn, Lactulose 5-60 mL 1-2/d, Sorbitol 70% 15-60 mL 1-2x/d, Poly-ethylene glycol PEG solution (GoLytely or Colyte) 300-1,000 mL up to 2 L/d or
    MiraLax powder
    is a new dry powder form of PEG without electrolytes approved for use by adults for occasional constipation.  It is soluble in water & forms a tasteless solution.
  4. Stimulant laxatives:
    Senna (Senokot) 8.6-17 mg 1-2x/d,  Disacodyl (Dulcolax, Correctol ) 5 mg tab 2 tab/d or 10 mg supp/day, or phenolphthalein  (Alophen pill) or anthraquinone compounds, to promote colonic secretion & motility

RX of Fecal Impaction:

Cleveland Clinic Journal of Med 1/1999;66:41 - Edy Soffer
Mayo Clin Proc 9/1998;73:881 - Charlene Prather

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The Tome II  Diagnostic Criteria for Constipation:
At least 12 weeks, which need not be consecutive, in the preceding 12 months of two or more of the following:

  1. Straining in more than 1 of 4 defecations.
  2. Lumpy or hard stools in more than 1 of 4 defecations
  3. Sensation of incomplete evacuation in more than 1 or 4 defecations
  4. Sensation of anorectal obstruction/blockade in more than 1 of 4 defecations
  5. Manual maneuvers to facilitate more than 1 in 4 defecations (e.g. digital evacuation, support of the pelvic floor) and/or
  6. Less than 3 defecations/week
    * Loose stools are not present, and there are insufficient criteria for irritable bowel syndrome.

The Rome II Criteria for Irritable Bowel Syndrome:
At least 12 weeks, which need not be consecutive, in the preceding 12 months of abdominal discomfort or pain that has 2 of 3 features:

  1. Relieved with defecation; and/or
  2. Onset associated with a change in frequency of stools; and/or
  3. Onset associated with a change in form (appearance) of stool.

The following symptoms cumulately support the diagnosis of irritable bowel syndrome: