CONSTIPATION


I. Definition

  1. Traditional definition = < 4 bowel movements per week
  2. Patients may define it based on stools that are hard in texture or difficult to pass
  3. "Rome III" diagnostic criteria-2 or more of:
    1. Straining at 25% or more of defecations
    2. Lump or hard stools in 25% or more of defecations
    3. Sensation of incomplete evaucation in 25% or more of defecations
    4. Sensation of anorectal obstruction in 25% or more of defecations
    5. Manual maneuvers to facilitate 25% or more of defecations
    6. < 3 defecations per week

    AND...Loose stools rarely present without use of laxatives

    AND...Doesn't meet criteria for irritable bowel syndrome

  4. Classification
    1. Functional (aka "primary")
      1. Normal transit
        1. Pt has symptoms, but stool movement through colon is normal
        2. Usually responds to fiber supplementation or laxatives
      2. Slow transit
        1. Stool transit time through colon is prolonged (can be confirmed on radiology motility studies)
        2. Symptomatology may include infrequency of urge to defecate; bloating; and abdominal discomfort
        3. Tends not to respond to fiber supplementation or laxatives
        4. May respond to biofeedback
      3. Outlet aka "pelvic floor dysfunction
        1. Lack of coordination of muscles of pelvic floor during attempted defecation, so stool is in rectum but is not expelled
        2. Colonic transit time is usually normal
        3. Symptomatology may include prolonged straining at stool, soft stools that are difficult to pass, and rectal discomfort
        4. Does not usually respond to traditional medical treatment; may respond to biofeedback and relaxation training
    2. Secondary
      1. Medications: aluminum-containing antacids, opiate analgesics, anticholinergives, certain antidepressants, antihistamines, antiparkinsonians, antipsychotics, anticonvulsants,antispasmodics, and diuretics
      2. Depression
      3. Diabetes mellitus
      4. Hypothyroidism
      5. Depression
      6. Anal fissures
      7. Autonomic neuropathy
      8. Colorectal Ca
      9. Hypercalcemia
      10. Hypokalemia
      11. Hypomagnesemia
      12. Multiple sclerosis
      13. Parkinson's
      14. Spinal cord injury

II. Risk factors

  1. Female gender
  2. Older age
  3. Inactivity
  4. Low caloric intake
  5. Low-fiber diet

III. Evaluation of the patient with constipation

  1. History
    1. Frequency of urge to defecate and actual defecation
    2. Stool consistency
    3. Sense of incompelte evacuation?
    4. Straining associated with bowel movements, particularly with soft stools? (suggests pelvic floor dysfunction)
    5. Symptoms accompanying or associated with bowel movements
    6. Other GI symtpoms including abodminal pain and bloating
    7. Complete medicaiton history including laxatives
    8. Nutritional habits
    9. Symptoms of depression?
    10. "Alarm" symptoms:
      1. Unintended weight loss
      2. Hematochezia
      3. Melena
      4. Narrowing of in stool caliber
      5. Acute onset of constipation in an older patient
  2. Physical examination
    1. Vital signs including weight
    2. Signs of anemia
    3. Abdominal exam for masses, hepatomegaly, etc.
    4. Anal/rectal exam including anal wink, hemorrhoids, fissures, rectal prolapse, warts
      1. Ask pt to strain as if having a bowel movement-lok for stool leakage (possible impaction) or rectal prolapse
      2. Check stools for occult blood
    5. "Alarm" signs:
      1. Unexplained weight loss
      2. Lack of anal wink (suggests potential sacral nerve pathology)
      3. Heme-positive stools
      4. Evidence of iron-deficiency anemia
      5. Rectal prolapse
  3. Other diagnostic evaluation
    1. Consider endoscopy if "alarm" symptoms or signs are present
  4. In one cohort study in 88 children (mean age 50mos) with intractible constipation (< 2 bowel movements weekly for > 3mos with no response to laxatives, enemas, or suppositories) and no h/o Hirschsprung disease, all of whom underwent spinal MRI, 9% had spinal cord abnormalities, including 6 with tethered cords.  All of these children had normal neurologic examinations and no neurologic symptoms (J. Peds. 145:409, 2004--JW)

IV. Management approaches for functional constipation

  1. First-line treatments
    1. Increased dietary fiber
    2. Increased water intake
    3. Increased exercise
    4. Biofeedback therapy in pts with pelvic floor dysfunction
  2. Second-line treatments
    1. Osmotic agents
      1. Magnesium hydroxide
      2. Lactulose
    2. Polyethylene glycol (Miralax)
      1. An osmotic laxative
      2. Not absorbed from the intestinal tract
      3. Hydrates stool without causing electrolyte shifts
      4. 68g PO may be the most effective dose
      5. Dose in kids = 0.8g/kg/d
  3. Other treatments
    1. Glycerin or Dulcolax (bisacodyl) suppositories (may cause rectal burning)
    2. Fleet's enema
    3. Enemas of soapsuds or milk/mollases slurry
    4. Mineral oil 15ml PO
    5. Stool softeners: colace (diocytl NaSulfosuccinate), maltsupex (malt soup extract)
    6. Senekot (senna concentrate, a direct bowel stimulant). Dose 1/2tsp BID for 1mo-1yr, 1tsp 1-5y, 2tsp 5-15y
    7. Tegaserod
      1. In a randomized trial in 1,348 adults (90% women) with chronic constipation, tegaserod 2-6mg BID vs. placebo x 12wks was ass'd with sig. higher response rates (43% vs. 25%); no rebound constipation seen during a 4-wk withdrawal period (Clin. Gastroenterol. Hepatol. 2:796, 2004--JW)
    8. Lubiprostone (Amitiza) 24ug BID with food
      1. A GI motility enhancer; activates chloride chanels in GI mucosa, increasing intestinal fluid secretion
  4. In kids 11mo-6yo with constipation, switching from cow's milk to soy milk can be effective (NEHM 339:1100, 1998--JW)

(Sources include AFP 84:299-306, 2011)