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Last updated on November 21st, 2021

Description of Medical Condition

A combination of changes in the frequency, size, consistency, and ease of stool passage, which leads to an overall decrease in volume of bowel movements. Very subjective, each individual has their own threshold level.

System(s) affected: Gastrointestinal

Genetics: Unknown (the condition may be familial)

Incidence/Prevalence in USA:

Higher at extremes of life, i.e., among infants/children and the elderly

Common; affects a majority of persons during their lifetimes

Predominant age: All ages can be affected; more frequent at the extremes of life (infancy and old age)

Predominant sex: Female > Male

Medical Symptoms and Signs of Disease

  • Less frequency of stooling than the patient perceives as ‘normal” (normal is 3-5 times/week)
  • Harder stool than “normal”
  • Smaller stools than normal (average < 35 grams/day is abnormal)
  • Impaction of stool secondary to hardness
  • Inspissated stool
  • Lack of consistent urgency to stool
  • Difficulty expelling feces from the rectum
  • Painful evacuation of feces
  • Lingering sense of incomplete emptying of the bowel
  • Abdominal fullness or a feeling of malaise secondary to inadequate bowel evacuation
  • Tenesmus


What Causes Disease?

1. Electrolyte abnormalities

  • Hypercalcemia
  • Hypokalemia

2. Hormonal abnormalities

  • Hypothyroidism
  • Diabetes

3. Congenital impediments, e.g., aganglionic megacolon (Hirschsprung disease) or excessively elongate, redundant, capacious bowel (dolichocolon)

4. Congenital or acquired neuromuscular bowel impairment (“pseudo-obstruction“)

5. Concomitant illness, injury, or debility

6. Mechanical bowel impediment (obstruction or ileus, due to any cause)

7. Inadequate fluid intake

Side-effect of drugs (e.g., anticholinergic agents, opiates)

  • Chronic abuse of laxatives or cathartics
  • Psychiatric, cultural, emotional, environmental factors
  • Painful fecal evacuation from anal disease (e.g., fissures)

Risk Factors

  • Extremes of life (very young and very old)
  • Neurosis
  • Polypharmacy
  • Sedentary life style or condition
  • Diet and fluid intake

Diagnosis of Disease

Differential Diagnosis

  • Congenital

– Hirschsprung

– Hypoganglionosis

– Congenital dilation of the colon

– Small left colon syndrome

  • Meconium ileus
  • “Normal” stooling with anxious patient or parent
  • Illnesses predisposing to constipation

– Dehydration

– Hypothyroidism

– Hypokalemia

– Hypercalcemia

  • Other causes of abdominal pain


Only necessary when other disorders are being considered

– CBC to detect anemia that may indicate colorectal neoplasm

– Thyroid functions

– Electrolytes, glucose, calcium

Drugs that may alter lab results: N/A

Disorders that may alter lab results: N/A

Pathological Findings

None in common, “functional” constipation

Paucity or absence of intramural enteric ganglia in certain cases of congenital or acquired megacolon

Neuromuscular abnormalities in certain cases of “pseudo-obstruction”

Special Tests

  • Endoscopic evaluation

– Flexible sigmoidoscopy

– Colonoscopy

  • In selected cases of long-standing constipation, timed measure of passage of ingested stool markers may help discern differing impediments
  • Anorectal motility in patients with suspected Hirschsprung or anorectal motility disorders


  • Plain (KUB) film of the abdomen may help to discern the extent and nature of the problem
  • Barium enema or barium swallow with small bowel follow through looking for anatomical defects (mass lesions, ileus)
  • Cineradiography of passage of barium, instilled in, then expelled from the rectosigmoid segment (“defecography”), may help define evacuation disorders in selected cases

Diagnostic Procedures

Digital rectal exam to rule out a rectal mass, check for blood in the stool, and define stool consistency

Sigmoidoscopy or colonoscopy is seldom required, unless needed to define an abnormality discovered by barium enema or when there is evidence of iron deficiency anemia or blood in the stool

Treatment (Medical Therapy)

Appropriate Health Care

Outpatient usually, except when investigation discloses an underlying lesion or obstruction that requires hospitalization

General Measures

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


Encourage exercise


If no anatomic abnormalities, increase fiber to approximately 15 gm/day (bran, fruit, green vegetables, and whole grain cereals and breads)

Encourage liberal intake of fluids

Patient Education

Define constipation and normal variations

Occasional mild constipation is normal

Instruction in consistent “bowel training” i.e., allowing adequate time for bowel evacuation in a quiet, unhurried environment; instruction in facilitating posture on commode, e.g., thighs flexed toward abdomen

Parents sometimes need more treatment/advice than the constipated child

Medications (Drugs, Medicines)

Drug(s) of Choice

  • Hydrophilic colloids (bulk-forming agents; not really drugs)

– Psyllium (Konsyl, Metamucil, Perdiem)

– Methylcellulose (Citrucel)

– Polycarbophil (Mitrolan, FiberCon)

  • Osmotic laxatives — appropriate for short-term use. The usual dose is 15 mL to 30 mL once or twice a day.

– Milk of magnesia 15-30 mL bid

– Magnesium citrate 15-30 mL bid

– Phosphate of soda 15-30 mL bid

– Lactulose (Chronulac) 15-30 mL bid O

– Sorbitoh 5-30 mL bid

– Alumina-magnesium (Maalox, Mylanta)

– Polyethylene glycol (MiraLax) 17 g in 8 oz of water q day

  • Stool softeners

– Docusate sodium (Colace) 100 mg bid


Any impediment to bowel transit, such as an obstructing lesion or ileus. Osmotic laxatives may result in overdistension or bowel perforation

Any acute intra-abdominal inflammatory condition

Renal and heart failure are relative contraindications


Advise patient against chronic use of irritant and osmotic laxatives

Significant possible interactions:

Magnesium containing laxatives

– Bind tetracyclines preventing their absorption

– Reduce the effectiveness of digitalis and phenothiazines

– Sodium polystyrene sulfonate (Kayexalate) bind and prevent neutralization of bicarbonate, leading to systemic alkalosis, which may be severe

Alternative Drugs

  • Lubricants (e.g., mineral oil) are unpalatable to many patients, subject to leakage, and impose the risk of aspiration
  • Emollient suppositories are useful, if at all, in allaying anorectal soreness
  • Irritant cathartics (stimulants)

– Ricinoleic acid or castor oil (Neoloid); 30-60 mL/day

– Phenolphthalein (Ex-Lax, Modane)

– Bisacodyl (Dulcolax); 2-3 tabs swallowed whole or 1 suppository bid

  • Motor and secretory properties

– Anthraquinones: senna (Senokot); 1 -2 cap or 15-30 mL qhs

  • Enemas (avoid soap suds — may lead to colitis)

– Sodium phosphate (Fleet enema)

  • Suppositories

– Osmotic: sodium phosphate

– Lubricant: glycerin

– Stimulatory: bisacodyl

  • Prokinetic agents

Patient Monitoring

What seems to be simple, “functional” constipation, if it persists, should be further investigated for a possible “organic” cause

Prevention / Avoidance

Because for some patients a tendency to constipation is habitual, instruction in proper diet, bowel training, and use of bulk-forming supplements must be reinforced

Possible Complications

  • Volvulus
  • Cancer risk
  • Acquired megacolon: in severe, long-standing cases
  • Cathartic colon: repeated laxative abuse
  • Fluid and electrolyte depletion: laxative abuse
  • Rectal ulceration (“stercoral ulcer”) related to recurrent fecal impaction
  • Anal fissures

Expected Course / Prognosis

Constipation that is only occasional, brief, and responsive to simple measures is harmless. That which is habitual can be a lifelong nuisance.


Associated Conditions

Debility either general, as in the aged, or that imposed by specific, underlying illness

Age-Related Factors


Consider Hirschsprung disease


Elderly persons, who have enjoyed regular bowel action throughout their lives, seldom suffer constipation due to age alone

Persons with a lifelong tendency to constipation often encounter increasing difficulty with advancing age

There is an increased incidence of colorectal neoplasms with age that may be associated with constipation.


Women with a tendency to constipation may find the condition more troublesome in the third trimester and require dietary adjustment and supplements


Costive bowel

Locked bowels

International Classification of Diseases

564.00 Constipation, unspecified

564.7 Megacolon, other than Hirschsprung

564.89 Other functional disorders of intestine

751.3 Hirschsprung disease and other congenital functional disorders of colon

See Also

Congenital megacolon Encopresis

Other Notes

– Obstipation refers to intractable constipation

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