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Constipation

- At least two of the following for 12 weeks in the previous 6 months: - <3 stools/week - Straining at least ¼; of the time - Hard stools at least ¼; of time - Need for manual assist at least ¼; of time - Sense of incomplete evacuation at least ¼; of time - Sense of anorectal blockade at least ¼; of time

- Hydrophilic colloids (bulk-forming agents) - Psyllium (Konsyl, Metamucil, Perdiem Fiber): 1 tbsp in 8-oz liquid PO daily up to TID - Methylcellulose (Citrucel): 1 tbsp in 8-oz liquid PO daily up to TID - Polycarbophil (Mitrolan, FiberCon): 2 caplets with 8-oz liquid PO up to QID

- Stimulants (irritate bowel, causing muscle contraction; usually combined with a softener; work in 8 to 12 hours) - Senna/docusate (Senokot-S, Ex-lax, Peri-Colace): 1 to 2 tablets or 15 to 30 mL PO at bedtime - Bisacodyl (Dulcolax, Correctol): 1 to 3 tablets PO daily

- Suppositories - Osmotic: sodium phosphate - Lubricant: glycerin - Stimulatory: Bisacodyl - Enemas: saline (Fleet enema)

para>Colorectal neoplasms may be associated with constipation; new-onset constipation after age 50 years is a "red flag." Use warm water enemas for impaction instead of sodium phosphate enema in geriatric patients. Sodium phosphate enemas have been associated with fatalities and severe electrolyte disturbances (1)[B].

Pediatric Considerations

Consider Hirschsprung disease (absence of colonic ganglion cells): 25% of all newborn intestinal obstructions, milder cases diagnosed in older children with chronic constipation, abdominal distension, decreased growth; 5:1 male-to-female ratio; associated with inherited conditions such as Down syndrome

Pregnancy Considerations

Avoid misoprostol. Other agents consider risks versus benefits.

EPIDEMIOLOGY

  • More pronounced in children and elderly
  • Predominant sex: female > male (2:1)
  • Nonwhites > whites

Incidence

  • 5 million office visits annually
  • 100,000 hospitalizations

Prevalence

~15% of population affected

ETIOLOGY AND PATHOPHYSIOLOGY

  • As food leaves the stomach, the ileocecal valve relaxes (gastroileal reflex) and chyme enters the colon (1 to 2 L/day) from the small intestine. In the colon, sodium is actively absorbed in exchange for potassium and bicarbonate. Water follows the osmotic gradient. Peristaltic contractions move chyme through the colon into the rectum. Chyme is converted into feces (200 to 250 mL).
  • Normal transit time is 4 hours to reach the cecum and 12 hours to reach the distal colon.
  • Defecation reflexively follows once stool reaches the rectal vault. This reflex can be inhibited by voluntarily contracting the external sphincter or facilitated by straining to contract the abdominal muscles while voluntarily relaxing the anal sphincter. Rectal distention initiates the defecation reflex. The urge to defecate occurs as rectal pressures increase. Distention of the stomach by food also initiates rectal contractions and a desire to defecate (gastrocolic reflex).
  • Primary constipationSlow colonic transit time (13%)Pelvic floor/anal sphincter dysfunction (25%)Functional: normal transit time and sphincter function, subjective symptoms (bloating, abdominal discomfort, perceived difficulty defecating, presence of hard stools) (69%)
  • Secondary constipationIrritable bowel syndrome (IBS)Endocrine dysfunction (diabetes mellitus, hypothyroid)Metabolic disorder (increased calcium, decreased potassium)Mechanical (obstruction, rectocele)PregnancyNeurologic disorders (Hirschsprung, multiple sclerosis, spinal cord injuries)
  • Medication effectAnticholinergic effects (antidepressants, narcotics, antipsychotics)Antacids (calcium, aluminum)Nondihydropyridine calcium channel blockers, especially verapamil

Genetics

Unknown but may be familial

RISK FACTORS

  • Extremes of life (very young and very old)
  • Polypharmacy
  • Sedentary lifestyle or condition
  • Improper diet and inadequate fluid intake

GENERAL PREVENTION

High-fiber diet, adequate fluids, exercise, and training to "obey the urge" to defecate

COMMONLY ASSOCIATED CONDITIONS

  • General debilitation (disease or aging)
  • Dehydration
  • Hypothyroidism
  • Hypokalemia
  • Hypercalcemia

DIAGNOSIS

ALERT

Red flags:

HISTORY

Rome III criteria (2)[C]:

  • At least two of the following for 12 weeks in the previous 6 months:<3 stools/weekStraining at least ¼; of the timeHard stools at least ¼; of timeNeed for manual assist at least ¼; of timeSense of incomplete evacuation at least ¼; of timeSense of anorectal blockade at least ¼; of time
  • Loose stools rarely seen without use of laxatives.

PHYSICAL EXAM

  • Vital signs, height, weight
  • Digital rectal exam (masses, pain, stool, fissures, hemorrhoids, anal tone)
  • Abdominal/gynecologic exam (masses, pain)
  • Neurologic exam

DIFFERENTIAL DIAGNOSIS

Congenital

  • Hirschsprung disease/syndrome
  • Hypoganglionosis
  • Congenital dilation of the colon
  • Small left colon syndrome

DIAGNOSTIC TESTS & INTERPRETATION

Primarily a clinical diagnosis

Initial Tests (lab, imaging)

CBC, glucose, TSH, calcium, and creatinine routinely and sigmoid/colonoscopy if red flags are present

Follow-Up Tests & Special Considerations

  • If condition is refractory, pursue further testing:ColonoscopyBarium enema to look for obstruction and/or megarectum, megacolon, or Hirschsprung disease
  • Additional testingMeasure colonic transit time by ingesting radiopaque (Sitz-Mark) markers.Plain abdominal film obtained 5 days later (120 hours): Retention of >20% markers indicates slow transit.Markers seen exclusively in distal colon/rectum suggests defecatory disorder.

Diagnostic Procedures/Other

Consider referral in refractory cases:

  • Balloon expulsion
  • Defecography using a barium paste
  • Anorectal manometry with a rectal catheter

Test Interpretation

  • Most cases are functional.
  • Paucity or absence of intramural enteric ganglia in certain cases of congenital or acquired megacolon
  • Neuromuscular abnormalities in certain cases of pseudo-obstruction

TREATMENT

Address immediate concerns:

  • Bloating/discomfort/straining: osmotic agents
  • Postoperative, after childbirth, hemorrhoids, fissures: stool softener to aid defecation
  • If impacted: manual disimpaction, then treat the chronic underlying condition

GENERAL MEASURES

  • Attempt to eliminate medications that may cause or worsen constipation.
  • Increase fluid intake.
  • Increase fiber in diet.
  • Enemas if other methods fail

MEDICATION

In patients with no known secondary causes of constipation, conservative nonpharmacologic treatment is recommended.

  • Regular exercise
  • Increased fluid intake
  • Bowel habit training

First Line

Bulking agents (must be accompanied by adequate amounts of liquid to be useful):

  • Hydrophilic colloids (bulk-forming agents)Psyllium (Konsyl, Metamucil, Perdiem Fiber): 1 tbsp in 8-oz liquid PO daily up to TIDMethylcellulose (Citrucel): 1 tbsp in 8-oz liquid PO daily up to TIDPolycarbophil (Mitrolan, FiberCon): 2 caplets with 8-oz liquid PO up to QID
  • Stool softenersDocusate sodium (Colace): 100 mg PO TID
  • Osmotic laxativesPolyethylene glycol (PEG) (MiraLax) 17 g/day PO dissolved in 4 to 8 oz of beverage (current evidence shows PEG to be superior to lactulose) (3)[B]Lactulose (Chronulac) 15 to 60 mL PO QHS (flatulence, bloating, cramping)Sorbitol: 15 to 60 mL PO QHS (as effective as lactulose)Magnesium salts (milk of magnesia) 15 to 30 mL PO once daily; avoid in renal insufficiency

Second Line

  • Stimulants (irritate bowel, causing muscle contraction; usually combined with a softener; work in 8 to 12 hours)Senna/docusate (Senokot-S, Ex-lax, Peri-Colace): 1 to 2 tablets or 15 to 30 mL PO at bedtimeBisacodyl (Dulcolax, Correctol): 1 to 3 tablets PO daily
  • Lubricants (soften stool and facilitate passage of the feces by its lubricating oily effects)Mineral oil (15 to 45 mL/day)Short-term use only. Can bind fat-soluble vitamins, with the potential for deficiencies; may similarly decrease absorption of some drugsAvoid in those at risk for aspiration (lipoid pneumonia)
  • SuppositoriesOsmotic: sodium phosphateLubricant: glycerinStimulatory: BisacodylEnemas: saline (Fleet enema)
  • Lubiprostone (Amitiza): a selective chloride channel activator; 24 Ī¼g PO BID
  • Linaclotide (Linzess): guanylate cyclase-C agonist; dose: 145 Ī¼g PO once daily; adult use onlyAvoid in children <6 years.Peripherally acting Ī¼-opioid receptor antagonists, indicated for opioid-induced constipation
  • Methylnaltrexone (Relistor): dose: 38 to <62 kg: 8 mg; 62 to 114 kg: 12 mg SC every other day PRNNaloxegol (Movantik): dose: 12.5 to 25.0 mg PO daily, discontinue other laxatives for 3 days when initiating naloxegol, avoid in patients on strong Cyp3A4 inhibitors due to increased naloxegol levels and risk of opioid withdrawal
  • Prokinetic agents (partial 5-HT4 agonists) have been withdrawn due to cardiac side effects; only available via IND protocols: tegaserod (Zelnorm), cisapride (Propulsid)
  • Other agents not approved by the FDA:Misoprostol (Cytotec): a prostaglandin that increases colonic motilityColchicine: neurogenic stimulation to increase colonic motility

ADDITIONAL THERAPIES

Other nonpharmacologic therapies include the following:

  • Biofeedback therapy
  • Behavior therapy
  • Probiotics
  • Electric stimulation

SURGERY/OTHER PROCEDURES

Surgery rarely indicated

INPATIENT CONSIDERATIONS

Toxic megacolon

Nursing

Manual disimpaction occasionally required in chronic refractory cases

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Encourage exercise and physical activity.

Patient Monitoring

If functional constipation persists, consider organic cause.

DIET

Increase fiber (bloating and gas can be problematic):

  • Gradually increase intake to 25 g/day over a 6-week period.
  • Bran (hard outer layer of cereal grains)
  • Vegetables and fruits
  • Whole grain foods
  • Encourage liberal intake of fluids.

PATIENT EDUCATION

  • Occasional mild constipation is normal.
  • Bowel training: the best time to move bowels is in the morning, after eating breakfast, when the normal bowel transit and defecation reflexes are functioning.

PROGNOSIS

  • Occasional constipation responsive to simple measures is harmless.
  • Habitual constipation can be a lifelong nuisance.
  • Patients with neurologic compromise can suffer from ill effects such as obstipation, impaction, and toxic megacolon.
  • No evidence for laxative dependence
  • No evidence for harm from stimulant use; melanosis coli may develop, but it is a benign condition.

COMPLICATIONS

  • Volvulus
  • Toxic megacolon
  • Acquired megacolon in severe, long-standing cases
  • Fluid and electrolyte depletion: laxative abuse
  • Rectal ulceration (stercoral ulcer) related to recurrent fecal impaction
  • Anal fissures

REFERENCES

11 Ori Y, Rozen-Zvi B, Chagnac A, et al. Fatalities and severe metabolic disorders associated with the use of sodium phosphate enemas: a single center's experience. Arch Intern Med. 2012;172(3):263-265.22 Bharucha AE, Pemberton JH, Locke GRIII. American Gastroenterological Association technical review on constipation. Gastroenterology. 2013;144(1):218-238.33 Lee-Robichaud H, Thomas K, Morgan J, et al. Lactulose versus polyethylene glycol for chronic constipation. Cochrane Database Syst Rev. 2010;(7):CD007570.

ADDITIONAL READING

  • Basilisco G, Coletta M. Chronic constipation: a critical review. Dig Liver Dis. 2013;45(11):886-893.
  • Bove A, Pucciani F, Bellini M, et al. Consensus statement AIGO/SICCR: diagnosis and treatment of chronic constipation and obstructed defecation (part I: diagnosis). World J Gastroenterol. 2012;18(14):1555-1564.
  • Dimidi E, Christodoulides S, Fragkos KC, et al. The effect of probiotics on functional constipation in adults: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2014;100(4):1075-1084.
  • Ford AC, Moayyedi P, Lacy BE, et al. American College of Gastroenterology monograph on the management of irritable bowel syndrome and chronic idiopathic constipation. Am J Gastroenterol. 2014;109(Suppl 1):S2-S26.
  • van Dijk M, Benninga MA, Grootenhuis MA, et al. Chronic childhood constipation: a review of the literature and the introduction of a protocolized behavioral intervention program. Patient Educ Couns. 2007;67(1-2):63-77.

CODES

ICD10

  • K59.00 Constipation, unspecified
  • K59.01 Slow transit constipation
  • K59.09 Other constipation
  • K59.02 Outlet dysfunction constipation

ICD9

  • 564.00 Constipation, unspecified
  • 564.01 Slow transit constipation
  • 564.09 Other constipation
  • 564.02 Outlet dysfunction constipation

SNOMED

  • 14760008 Constipation (disorder)
  • 35298007 Slow transit constipation
  • 111360009 Obstipation (disorder)
  • 85920003 Constipation by outlet obstruction

CLINICAL PEARLS

  • Constipation is unsatisfactory defecation with infrequent stools, difficult stool passage, or both for 3 months.
  • Functional constipation (normal transit time and sphincter function) is most common.
  • Workup red flags: onset >50 years, hematochezia/melena, unintentional weight loss, anemia, neurologic defects
  • Osmotic agents (PEG) have the most evidence supporting clinical effectiveness.