Constipation – Causes, Symptoms, Diagnosis, Treatment and Ongoing care
A group of syndromes with similar findings that include unsatisfactory defecation characterized by infrequent stools, difficult stool passage, or both. Characteristics include fewer than 3 bowel movements a week, hard stools, excessive straining, prolonged time spent on the toilet, a sense of incomplete evacuation, and abdominal discomfort/bloating.
- System(s) affected: Gastrointestinal (GI)
- Synonym(s): Obstipation
Increased incidence of colorectal neoplasms with age may be associated with constipation; thus, new onset of constipation after 50 years of age is considered a “red flag.”
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:female ratio. Associated with inherited conditions such as Down syndrome.
- Predominant age: May affect all ages, but more pronounced in children and elderly
- Predominant sex: Female > Male (2:1)
- Non-whites > whites
- 5 million office visits annually
- 100,000 hospitalizations
∼15% of population effected
- Extremes of life (very young and very old)
- Sedentary lifestyle or condition
- Improper diet and inadequate fluid intake
Unknown, but condition may be familial
High-fiber diet, adequate fluids, exercise, and bowel training to “obey the urge” to defecate are useful preventive strategies.
- As food leaves the stomach, the ileocecal valve relaxes (gastroileal reflex) and chyme enters the colon (1–2 L/day). Peristaltic contractions move the chyme through the colon into the rectum. In the colon, sodium is actively absorbed in exchange for potassium and bicarb—water follows because of the generated osmotic gradient. The chyme is converted into feces (200–250 mL).
- Normal transit time for a meal to reach the cecum is 4 hours, and to the pelvic colon 8 hours later. Transit then slows to the anus. Rectal distention initiates the defecation reflex.
- Defecation follows as a reflex that can be inhibited by voluntarily contracting the external sphincter or facilitated by straining to contract the abdominal muscles while voluntarily relaxing the anal sphincter. The urge to defecate occurs as rectal pressures increase. Distention of the stomach by food also initiates rectal contractions and a desire to defecate.
- Primary constipation:
- Slow colonic transit time (13%)
- Pelvic floor/anal sphincter dysfunction (25%)
- Functional—normal transit time and sphincter function, yet problems (bloating, abdominal discomfort, perceived difficulty going, presence of hard stools) (69%)
- Secondary constipation:
- Irritable bowel syndrome (IBS)
- Endocrine dysfunction (diabetes mellitus, hypothyroid)
- Metabolic disorder (increased calcium, decreased potassium)
- Mechanical (obstruction, rectocele)
- Neurologic disorders (Hirschsprung, multiple sclerosis, spinal cord injuries)
- Medication effect:
- Anticholinergic effects (antidepressants, narcotics, antipsychotics)
- Antacids (calcium, aluminum)
- Calcium channel blockers
Commonly Associated Conditions
- Debility, either general as in the aged or that imposed by specific underlying illness
A group of syndromes with similar findings that include unsatisfactory defecation characterized by infrequent stools, difficult stool passage, or both.
- New onset after age of 50
- Unintentional weight loss
- Neurological defects
Ask about the Rome III criteria (1):
- At least 2 of the following, for 12 weeks, in the previous 6 months:
- Fewer than 3 stools/week
- Straining at least 1/4 of the time
- Hard stools at least 1/4 of the time
- Need for manual assist at least 1/4 of the time
- Sense of incomplete evacuation at least 1/4 of the time
- Sense of anorectal blockade at least 1/4 of the time
- Loose stools rarely seen without use of laxatives
- Digital rectal exam (masses, pain, stool, fissures, hemorrhoids, anal tone)
- Abdominal/gynecological exam (masses, pain)
- Neurological exam
Diagnostic Tests & Interpretation
For the most part, this is a clinical diagnosis, as evidence to support the use of routine labs/x-rays/scoping is lacking in the workup of constipation (2).
Initial lab tests
However, the American Gastroenterological Association guidelines suggest complete blood count, BS, TSH, calcium, and creatinine routinely and sigmoid/colonoscopy if red flags are present (3).
If condition is refractory to empiric approach, pursue further testing:
- Barium enema to look for obstruction and/or megarectum, megacolon, or Hirschsprung disease
Follow-Up & Special Considerations
Measure colonic transit time by ingesting radiopaque (Sitz-Mark) markers:
- Plain abdominal film obtained 5 days later (120 hours): Retention >20% markers indicates slow transit
- Markers seen exclusively in distal colon/rectum suggests defecatory disorder.
Consider referral to evaluate defecation:
- Balloon expulsion
- Defecography using a barium paste
- Anorectal manometry with a rectal catheter
- 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
- Hirschsprung disease/syndrome
- Congenital dilation of the colon
- Small left colon syndrome
- Meconium ileus
- Other causes of abdominal pain
Address immediate concerns:
- Bloating/discomfort/straining: Osmotic agents
- Post-op, childbirth, hemorrhoids, fissures: Stool softener to make defecation easier
- Stimulants and suppositories
- Manual disimpaction as needed, then approach the chronic condition
- In patients with no known secondary causes of constipation, conservative nonpharmacologic treatment measures generally are recommended, including:
- Regular exercise
- Increased fluid intake
- Bowel habit training
- Other nonpharmacologic therapies include:
- Biofeedback therapy
- Behavior therapy
- Electric stimulation
Bulking agents (need to be accompanied by adequate amounts of liquid to be useful):
- Hydrophilic colloids (bulk-forming agents):
- Psyllium (Konsyl, Metamucil, Perdiem Fiber): 1 rounded tsp in liquid p.o. daily up to t.i.d.
- Bran methylcellulose (Citrucel): 1 rounded tsp in 8 oz cold water p.o. daily up to t.i.d.
- Polycarbophil (Mitrolan, FiberCon): 1 g p.o. q.i.d.
- Stool softeners:
- Docusate sodium (Colace): 100 mg b.i.d.
- Osmotic laxatives:
- Polyethylene glycol (MiraLax) (0.8 mg/kg/d) 17 g daily (current evidence shows PEG to be superior to lactulose) (4)[A]
- Saccharines Lactulose (Chronulac) 15–60 ml q.h.s. (flatulence, bloating, cramping side effects)
- Sorbitol 15–60 ml q.h.s. (as effective as lactulose)
- Magnesium salts (Milk of Magnesia) avoid in renal insufficiency
Stimulants (irritate bowel causing muscle contraction; usually combined with a softener; work in 8–12 hours)
- Senna/docusate (Senokot-S, ex-lax) 1–2 capsules or 15–30 mL at bedtime
- Bisacodyl/docusate (Dulcolax, Correctol) 2–3 tablets daily
- Casanthranol/docusate (Peri-Colace) lubricants (contain mineral oil, coating the stool)
- Short-term use only. Can bind fat-soluble vitamins with the potential for deficiencies. May similarly decrease absorption of some drugs.
- Avoid in those at risk for aspiration (lipid pneumonia).
- Osmotic: Sodium phosphate
- Lubricant: Glycerin
- Stimulatory: Bisacodyl
- Sodium phosphate (Fleet enema)
- Lubiprostone (Amitiza): A selective chloride channel activator; 24 mcg b.i.d.
- Avoid in pregnancy and breastfeeding
- Prokinetic agents (partial 5-HT4 agonists): Have been withdrawn due to cardiac side effects (tegaserod [Zelnorm], cisapride [Propulsid])
- Other agents not approved by the Food and Drug Administration:
- Misoprostol (Cytotec): A prostaglandin that increases colonic motility (5)
- Colchicine: Neurogenic stimulation to increase colonic motility (6)
- Attempt to eliminate medications that may cause or worsen constipation
- Increase fluid intake
- Increase fiber in diet
- Enemas if other methods fail
Biofeedback with artificial silicon stool
Surgery rarely indicated
Manual disimpaction occasionally required in difficult chronic situations
Encourage exercise and physical activity.
If what seems to be simple, functional constipation persists, further investigate for a possible organic cause.
Increase fiber, but bloating and gas can be problematic:
- Gradually increase intake to 25 grams/day over a 6-week period.
- Insoluble, less fermentable fiber, like wheat bran, tends to be better tolerated.
- Bran (hard outer layer of cereal grains)
- Vegetables and fruits
- Whole grain foods
- Encourage liberal intake of fluids.
- Occasional mild constipation is normal.
- Instruction in consistent bowel training; the best time to move bowels is in the morning, after eating breakfast, when the normal bowel transit and defecation reflexes are typically functioning to move the bowels.
- Constipation that is only occasional, brief, and responsive to simple measures is harmless.
- That which is habitual can be a lifelong nuisance.
- Those with neurologic compromise can suffer from ill effects such as obstipation and impaction to toxic megacolon.
- No evidence for dependence
- No evidence for harm from stimulant use; melanosis coli may develop, but it is a benign condition (7)
- 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
1. Longstreth GF, Thompson WG, Chey WD, et al. Functional bowel disorders. Gastroenterology. 2006;130:1480–91.
2. American College of Gastroenterology Chronic Constipation Task Force. An evidence-based approach to the management of chronic constipation in North America. Am J Gastroenterol. 2005;100 (Suppl 1):S1–4.
3. Locke GR, Pemberton JH, Phillips SF. American Gastroenterological Association Medical Position Statement: guidelines on constipation. Gastroenterology. 2000;119:1761–6.
4. Lee-Robichaud H, Thomas K, Morgan J et al. Lactulose versus Polyethylene Glycol for Chronic Constipation. Cochrane Database Syst Rev. 2010;7:CD007570.
5. Roarty TP, Weber F, Soykan I, et al. Misoprostol in the treatment of chronic refractory constipation: results of a long-term open label trial. Aliment Pharmacol Ther. 1997;11:1059–66.
6. Verne GN, Davis RH, Robinson ME, et al. Treatment of chronic constipation with colchicine: randomized, double-blind, placebo-controlled, crossover trial. Am J Gastroenterol. 2003;98:1112–6.
7. Müller-Lissner SA, Kamm MA, et al. Myths and misconceptions about chronic constipation. Am J Gastroenterol. 2005;100:232–42.
Spinzi G, Amato A, Imperiali G et al. Constipation in the elderly: management strategies. Drugs Aging. 2009;26:469–74.
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.
564.00 Constipation, unspecified
- 14760008 Constipation (disorder)
- 111360009 obstipation (disorder)
- Constipation can be characterized as unsatisfactory defecation, with infrequent stools, difficult stool passage, or both, for 3 months.
- Functional constipation (normal transit time and sphincter function) seen most often
- Workup is necessary in the presence of red flags: Onset >50 yrs, hematochezia/melena, unintentional weight loss, anemia, neurological defects
- Best evidence for effectiveness is for osmotic agents (polyethylene glycol [PEG]).