Resident Editor: Kendra Moore, MD, MBE

Faculty Editor: Aparajita Singh, MD, MPH

Background

• Constipation is extremely common: prevalence about 16% in adults overall and 33% adults >60
• Cause of 2.5M physician visits and 92,000 hospital visits annually

Diagnostic criteria for functional constipation (Rome IV):

• 2+ of the following for at least 3 months:
  • <3 spontaneous BMs per week
  • straining during >25% of BMs
  • lumpy or hard stools during >25% of BMs
  • sensation of incomplete evacuation during >25% of BMs
  • sensation of anorectal obstruction for >25% of BMs
  • Manuel maneuvers to facilitate >25% of BMs
• Loose stools are rarely present without the use of laxatives
• Insufficient criteria for IBS- consider this particularly if there is recurrent abd pain

DDx:

Types of functional constipation:

• Normal transit (normal frequency but hard stool or straining) 
• Slow transit (due to abnormal innervation or visceral myopathy)
• Disorders of defecation: lack of coordination of recto-anal and pelvic muscles

Secondary causes:

• Drugs:  including anticholinergics (antihistamines, antispasmodics, antidepressants, and antipsychotics), antacids, iron supplements, opiates, calcium channel blockers, calcium, diuretics, and anti-parkinsonian drugs
• Obstruction: Cancer, strictures, adhesions, rectocele, external compression
• Endocrine: hypothyroidism, diabetes, hyperparathyroidism, panhypopituitarism
• Metabolic: hypercalcemia, hypokalemia hypomagnesemia, uremia
• Neurologic: spinal cord injury, parkinsonism, MS, CVA, Hirschprung
• Psychiatric: depression, anorexia nervosa, physical and sexual abuse
• Miscellaneous: amyloid, scleroderma, immobility

Evaluation

• History – Features of IBS (ie associated with abd pain), features of pelvic floor dysfunction (ie excessive straining, digital manipulation, spending long time evacuating)
  • Alarm features (colonoscopy recommended) – GI bleeding, change in stool caliber, weight loss >10 lb, family history of colon cancer, anemia, + FOBT, >50 with acute onset
• Physical – Abdominal palpable mass, rectal exam to r/o mass/impaction, anal sphincter muscle function
• Tests
  • In the absence of alarm signs and symptoms only a CBC is necessary. Unless other clinical features warrant otherwise, Chem Panel, TSH are not recommended just for chronic constipation.
  • A colonoscopy should not be performed routinely in all patients. Only those with alarm features or those who are due for colon cancer screening should undergo colonoscopy.
  • If history is suggestive of pelvic floor dysfunction – refer for ano-rectal manometry (simple test, done without sedation) to confirm the diagnosis.
  • These patients may respond well to fiber/laxative but treatment with biofeedback is quite successful (improvement in 70% patients) with training to relax the pelvic floor and restore recto-anal coordination.
  • Colonic Transit study done with sitz marker (multiple X rays after swallowing radiopaque markers) usually considered if patients fail  medical management and have refractory symptoms

Treatment for primary constipation:

Step 1: lifestyle modifications: increased water and fiber intake, increased exercise. Recommended water intake is 8 cups a day and fiber intake is 25-30g/day. 2/3 of Americans don't get their recommended daily amount of fiber.

In general, the average content of dietary fiber per serving of each of the food groups is:

Fruits and vegetables—1 to 3 grams
Nuts—2 to 3 grams per ounce
Beans, chickpeas, lentils; most berries—4 to 6 grams
White bread, white rice, refined pasta—less than 1 gram

Unrefined grains such as bran, whole wheat bread, brown rice and barley are excellent sources of fiber. Bulgar, barley, quinoa, oatmeal and bran cereals have between 3 and 6 grams per half cup.

Step 2: Add an inexpensive osmotic agent such as polyethylene glycol or milk of magnesia.

Step 3: Add stimulant laxative (eg bisacodyl oral or suppository or glycerine suppositories). Suppositories are preferably administered 30 min before meals to synergize with the gastrocolic response.

Laxative Agents:

When to refer:  Refractory symptoms, red flag symptoms or symptoms suggestive of pelvic floor dysfunction- refer to gastroenterology for colonoscopy, ano-rectal manometry or colonic transit study

References

American Gastroenterological Association Medical Position Statement: Guidelines on constipation. Gastroenterology 2013:144:211-217

Drossman DA, Hasker WL. Rome IV-functional GI disorders: disorders of gut-brain interaction. Gastroenterology 2016; 150:1257–1261.

Jamshed et al. Diagnostic approach to chronic constipation in adults. Am Fam Physician. 2011 Aug 1;84(3):299-306.

Longstreth et al. Functional Bowel Disorders. Gastroenterology. 2006;130 (5):1480

Mounsey et al. Management of constipation in older adults. Am Fam Physician. 2015 Sep 15;92(6):500-504.