Constipation is difficult or infrequent passage of stool, hardness of stool, or a feeling of incomplete evacuation. (See also Constipation in Children.)
No bodily function is more variable and subject to external influences than defecation. Bowel habits vary considerably from person to person and are affected by age, physiology, diet, and social and cultural influences. Some people have unwarranted preoccupation with bowel habits. In Western society, normal stool frequency ranges from 2 to 3/day to 2 to 3/week.
Many people incorrectly believe that daily defecation is necessary and complain of constipation if stools occur less frequently. Others are concerned with the appearance (size, shape, color) or consistency of stools. Sometimes the major complaint is dissatisfaction with the act of defecation or the sense of incomplete evacuation after defecation. Constipation is blamed for many complaints (abdominal pain, nausea, fatigue, anorexia) that are actually symptoms of an underlying problem (eg, irritable bowel syndrome [IBS], depression). Patients should not expect all symptoms to be relieved by a daily bowel movement, and measures to aid bowel habits should be used judiciously.
Patients who have obsessive-compulsive disorder often feel the need to rid the body daily of “unclean” wastes. Such patients often spend excessive time on the toilet or become chronic users of cathartics.
Etiology of Constipation
Acute constipation suggests an organic cause, whereas chronic constipation may be organic or functional (see table Causes of Constipation).
In many patients, constipation is associated with sluggish movement of stool through the colon. This delay may be due to medications or illicit drugs (eg, opioids), organic conditions, or a disorder of defecatory function (ie, pelvic floor dysfunction), or a disorder that results from diet (see table Foods Often Affecting Gastrointestinal Function). Patients with disordered defecation do not generate adequate rectal propulsive forces, do not relax the puborectalis and the external anal sphincter during defecation, or both. In IBS, patients have symptoms (eg, abdominal discomfort and altered bowel habits) but generally normal colonic transit and anorectal functions. However, IBS-disordered defecation may coexist.
Excessive straining, perhaps secondary to pelvic floor dysfunction, may contribute to anorectal pathology (eg, hemorrhoids, anal fissures, rectal prolapse) and possibly even to syncope.
Fecal impaction, which may cause or develop from constipation, is also common among older adults, particularly with prolonged bed rest or decreased physical activity. It is also common after barium has been given by mouth or enema.
Causes of Constipation
Causes | Examples |
|---|---|
Acute constipation* | |
Bowel obstruction | |
Adynamic ileus | Peritonitis, major acute illness (eg, sepsis), head or spinal trauma, bed rest |
Medications | Anticholinergics (eg, antihistamines, antipsychotics, antiparkinsonian medications, antispasmodics), cations (iron, aluminum, calcium, barium, bismuth), opioids, calcium channel blockers, general anesthetics Constipation shortly after start of therapy with the medication |
Chronic constipation* | |
Colonic tumor | |
Metabolic disorders | Diabetes mellitus, hypothyroidism, hypocalcemia or hypercalcemia, pregnancy, uremia, porphyria |
Central nervous system disorders | Parkinson disease, multiple sclerosis, stroke, spinal cord lesions |
Peripheral nervous system disorders | Hirschsprung disease, neurofibromatosis, autonomic neuropathy |
Systemic disorders | Systemic sclerosis, amyloidosis, inflammatory myopathy, myotonic dystrophy |
Functional disorders | Slow-transit constipation, irritable bowel syndrome, pelvic floor dysfunction (functional defecatory disorders) |
Dietary factors | Low-fiber diet, sugar-restricted diet, chronic laxative abuse |
Dyssynergic defecation | Asynchrony of anorectal muscles leading to difficult evacuation and constipation; typically, sensation of incomplete evacuation plus excessive straining and, particularly, digital disimpaction |
* There is some overlap between acute and chronic causes of constipation. In particular, medications are common causes of chronic constipation. | |
Foods Often Affecting Gastrointestinal Function
Foods likely to cause loose bowel movements and/or excessive gas |
All caffeine-containing beverages especially coffee with chicory |
Peaches, pears, cherries, apples |
Fruit juices: Orange, cranberry, apple |
Asparagus and cruciferous vegetables such as broccoli, cauliflower, cabbage, and Brussels sprouts |
Bran cereal, whole wheat bread, high-fiber foods |
Pastry, candy, chocolate, waffle syrup, doughnuts |
Alcohol |
Milk and milk products (in lactose-sensitive people) |
Foods likely to cause constipation or help control loose bowel movements |
White rice, white bread, potatoes, pasta |
Meat, veal, poultry, fish |
Cooked vegetables |
Bananas |
Evaluation of Constipation
History
History of present illness should ascertain a lifetime history of the patient’s stool frequency, consistency, and need to strain or use perineal maneuvers (eg, pushing on the perineum, gluteal region, or recto-vaginal wall) during defecation. Satisfaction after defecation should be obtained, including frequency and duration of laxative or enema use. The presence, amount, and duration of blood in the stool should also be elicited.
Review of systems should seek symptoms of causative disorders, including a change in caliber of the stool or blood in the stool (possibly due to cancer). Systemic symptoms suggesting chronic diseases (eg, weight loss) should also be sought.
Past medical history should ask about known causes, including previous abdominal surgery and symptoms of metabolic (eg, hypothyroidism, diabetes mellitus) and neurologic (eg, Parkinson disease, multiple sclerosis, spinal cord injury) disorders. Prescription and nonprescription medication use should be carefully assessed, with specific questioning about anticholinergics and opioids.
Physical examination
A general examination is done to look for signs of systemic disease, including fever and cachexia.
Abdominal masses should be sought by palpation.
A rectal examination should be done not only for fissures, strictures, blood, or masses (including fecal impaction) but also to evaluate anal resting tone (the puborectalis “lift” when patients squeeze the anal sphincter), perineal descent during simulated evacuation, and rectal sensation. Patients with defecatory disorders may have increased anal resting tone (or anismus), reduced (ie, < 2 cm) or increased (ie, > 4 cm) perineal descent, and/or paradoxical contraction of the puborectalis during simulated evacuation.
Red flags
Certain findings raise suspicion of a more serious etiology of chronic constipation:
Distended, tympanitic abdomen
Vomiting
Blood in stool
Weight loss
Severe constipation of recent onset/worsening in older adults
Interpretation of findings
Certain symptoms (eg, a sense of anorectal blockage, prolonged or difficult defecation, need for digital disimpaction), particularly when associated with abnormal (ie, increased or reduced) perineal motion during simulated evacuation, suggest a defecatory disorder. A tense, distended, tympanitic abdomen, particularly when there is nausea and vomiting, suggests mechanical obstruction.
Chronic constipation with modest abdominal discomfort in a patient who has used laxatives for a long time suggests slow-transit constipation.
Acute constipation coincident with the start of a constipating medication in patients without red flag findings suggests the medication is the cause.
New-onset constipation that persists for weeks or occurs intermittently with increasing frequency or severity, in the absence of a known cause, suggests colonic tumor or other causes of partial obstruction.
Excessive straining or prolonged or unsatisfactory defecation, with or without anal digitation, suggests a defecatory disorder.
Patients with fecal impaction may have cramps and may pass watery mucus or fecal material around the impacted mass, mimicking diarrhea (overflow diarrhea).
Patients with IBS typically have abdominal pain with disordered bowel habits. Patients with chronic constipation who do not meet the criteria for IBS may have functional constipation (1).
Testing
Testing is guided by clinical presentation and the patient's diet history.
Constipation with a clear etiology (medications, trauma, bed rest) may be treated symptomatically without further study. Patients with symptoms of bowel obstruction require flat and upright abdominal radiographs, possibly a water-soluble contrast enema to evaluate for colonic obstruction, and possibly a CT scan or barium radiograph of the small intestine (see also diagnosis of intestinal obstruction). Most patients without a clear etiology should have colonoscopy and a laboratory evaluation (complete blood count, thyroid-stimulating hormone, fasting glucose, electrolytes, and calcium).
Further tests are usually reserved for patients with abnormal findings on the previously mentioned tests or who do not respond to symptomatic treatment. The current American Gastroenterological Association's 2013 medical position statement on constipation suggests a trial of fiber and/or over-the-counter laxatives. If this trial fails, anorectal manometry with balloon expulsion should be done to identify pelvic floor disorders and dyssynergic defecation (2). If manometry is negative and the primary complaint is infrequent defecation, colonic transit times should be measured with radiopaque markers (Sitz markers), scintigraphy, or a wireless motility capsule. In patients with chronic constipation, it is important to distinguish between slow-transit constipation (abnormal Sitz marker radiopaque study) and pelvic floor muscle dysfunction (markers retained only in distal colon). (See also the American College of Gastroenterology's 2021 clinical guidelines for the management of benign anorectal disorders.)
Evaluation references
1. Lacy BE, Mearin F, Chang L, et al: Bowel disorders. Gastroenterology 150(6):1393–1407, 2016. doi: 10.1053/j.gastro.2016.02.031
2. Rao SCS, Tanisa Patcharatrakul T: Diagnosis and treatment of dyssynergic defecation. J Neurogastroenterol Motil 22(3):423–435, 2016. doi: 10.5056/jnm16060
Treatment of Constipation
Possibly discontinuation of causative medications (some may be necessary)
Increase in dietary fiber
Possibly trial with a brief course of osmotic laxatives
Any identified conditions should be treated.
See table Agents Used to Treat Constipation for a summary. Laxatives should be used judiciously. Some (eg, phosphate, bran, cellulose) bind medications and interfere with their absorption. Rapid fecal transit may rush some medications and nutrients beyond their optimal absorptive locus. Contraindications to laxative and cathartic use include acute abdominal pain of unknown origin, inflammatory bowel disorders, intestinal obstruction, gastrointestinal bleeding, and fecal impaction. Available evidence on efficacy, cost, and potential adverse effects of medications should be considered when treating patients and have been addressed in professional society guidelines (1).
Diet and behavior
The diet should contain enough fiber (typically 15 to 20 g/day) to ensure adequate stool bulk. Vegetable fiber, which is largely indigestible and unabsorbable, increases stool bulk. Certain components of fiber also absorb fluid, making stools softer and facilitating their passage. Fruits and vegetables are recommended sources, as are cereals containing bran. Fiber supplementation is particularly effective in treating normal-transit constipation but is not very effective for slow-transit constipation or defecatory disorders.
Patients with obsessive-compulsive disorder require treatment for that disorder. In addition, physicians must explain that daily bowel movements are not essential, that the bowel must be given a chance to function, and that frequent use of laxatives or enemas (> once every 3 days) denies the bowel that chance.
Agents Used to Treat Constipation
Agent | Some Adverse Effects |
|---|---|
Fiber* | |
Bran | Bloating, flatulence, iron and calcium malabsorption |
Bloating, flatulence | |
Less bloating than with other fiber agents | |
Bloating, flatulence | |
Emollients | |
Ineffective for severe constipation | |
Rectal irritation | |
Lipid pneumonia, malabsorption of fat-soluble vitamins, dehydration, fecal incontinence | |
Osmotic agents | |
Transient abdominal cramps, flatulence | |
Fecal incontinence (related to dosage) | |
Magnesium | Magnesium toxicity, dehydration, abdominal cramps, fecal incontinence, diarrhea |
Sodium phosphate | Rare cases of acute renal failure |
Stimulants | |
Anthraquinones | Abdominal cramps, dehydration, melanosis coli, malabsorption, possible deleterious effects on intramural nerves |
Fecal incontinence, hypokalemia, abdominal cramps, rectal burning with daily use of suppository form | |
Abdominal pain, flatulence Contraindicated in children < 2 years and in patients with known or suspected mechanical gastrointestinal obstruction | |
Nausea, particularly on empty stomach, and headache | |
Dizziness, uncommonly urinary tract infection | |
Headache, abdominal pain, increased risk of depression and suicidal attempts | |
Severe diarrhea, dehydration, abdominal distension, flatulence, and dizziness | |
Enemas | |
Fecal incontinence, mechanical trauma | |
Tap water | Mechanical trauma |
Phosphate | Accumulated damage to rectal mucosa, hyperphosphatemia§, mechanical trauma |
Soapsuds | Accumulated damage to rectal mucosa, mechanical trauma |
Peripherally acting mu-opioid receptor antagonists (PAMORAs) | |
Contraindicated in patients with bowel obstruction Possibility of increased risk of cardiovascular events (eg, myocardial infarction) | |
Weight-based subcutaneous dosing in patients with advanced illness If no improvement after 3 days, reinitiate prior laxative therapy Contraindicated in known or suspected bowel obstruction | |
Contraindicated in known or suspected bowel obstruction | |
Contraindicated in known or suspected bowel obstruction | |
* The dose of fiber supplements should be gradually increased over several weeks to the recommended dose. Fiber supplements are given orally. | |
† This agent is available by prescription only. | |
§ Because of the risk of hyperphosphatemia, phosphate should not be used in patients with kidney disease. | |
Adapted from Romero Y, Evans JM, Fleming KC, Phillips SF: Constipation and fecal incontinence in the elderly population. Mayo Clin Proc 71(1):81–92, 1996. doi: 10.4065/71.1.81; by permission. | |
Types of laxatives
Bulking agents
Osmotic agents
In general, osmotic agents are reasonably safe even when used regularly. However, sodium phosphate should not be used for bowel cleansing because it may rarely cause acute renal failure even after a single use for bowel preparation. These events occurred primarily in older adults, those with preexisting renal disease, and those who were taking medications that affect renal perfusion or function (eg, diuretics, angiotensin-converting enzyme inhibitors, angiotensin II
Secretory or stimulant cathartics
Adverse effects include allergic reactions, electrolyte depletion, melanosis coli, and cathartic colon. Melanosis coli is a brownish black colorectal pigmentation of unknown composition. Cathartic colon refers to alterations in colonic anatomy observed on barium enema in patients with chronic stimulant laxative use. Cathartic colon can cause constipation that leads to more laxative use and thus more constipation, creating a vicious circle. It is unclear whether cathartic colon, which has been attributed to destruction of myenteric plexus neurons by anthraquinones, is caused by currently available agents or other neurotoxic agents (eg, podophyllin), which are no longer available. There does not seem to be an increased risk of colon cancer with long-term anthraquinone use.
Enemas can be used, including tap water and commercially prepared hypertonic solutions.
Emollient agentsDocusate is a surfactant, which allows water to enter the fecal mass to soften and increase its bulk.
Peripherally acting mu-opioid receptor antagonists
Fecal impaction
Fecal impaction is treated initially with enemas of tap water followed by small enemas (100 mL) of commercially prepared hypertonic solutions.
Treatment reference
1. Chang L, Chey WD, Imdad A, et al. American Gastroenterological Association-American College of Gastroenterology Clinical Practice Guideline: Pharmacological Management of Chronic Idiopathic Constipation. Gastroenterology. 2023;164(7):1086-1106. doi:10.1053/j.gastro.2023.03.214
Geriatrics Essentials: Constipation
Constipation is common among older adults because of low-fiber diets, lack of exercise, coexisting medical conditions, and use of constipating medications. Many older adults have misconceptions about normal bowel habits and use laxatives regularly.
Other changes that predispose older adults to constipation include increased rectal compliance and impaired rectal sensation (such that larger rectal volumes are needed to elicit the desire to defecate).
Key Points
Medication causes are common (eg, use of anticholinergics or opioids).
Be wary of bowel obstruction when constipation is acute and severe.
If a trial of fiber and/or laxatives fails, anorectal manometry with balloon expulsion should be done to exclude pelvic floor dysfunction.
More Information
The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
American Gastroenterological Association: Medical position statement on constipation (2013)
American College of Gastroenterology: Clinical guidelines for the management of benign anorectal disorders (2021)
American Gastroenterological Association-American College of Gastroenterology: Clinical Practice Guideline: Pharmacological Management of Chronic Idiopathic Constipation (2023)
Dyschezia
Dyschezia (which also may be referred to as dyssynergia, disordered evacuation, dysfunction of pelvic floor or anal sphincters, or functional defecatory disorders) is difficulty defecating. Patients sense the presence of stool and the need to defecate but are unable. It results from a lack of coordination of pelvic floor muscles and anal sphincters. Diagnosis requires anorectal testing. Treatment is difficult, but biofeedback may be of benefit.
Etiology of Dyschezia
Normally, when a person tries to defecate, rectal pressure rises in coordination with relaxation of the external anal sphincter. This process may be affected by 1 or more dysfunctions (eg, impaired rectal contraction, excessive contraction of the abdominal wall, paradoxic anal contraction, failure of anal relaxation) of unclear etiology. Functional defecatory disorders may manifest at any age. In contrast, Hirschsprung disease, which is due to an absent recto-anal inhibitory reflex, is almost always diagnosed in infancy or childhood. People with irritable bowel syndrome (IBS) may have IBS-disordered defecation, causing dyschezia.
Symptoms and Signs of Dyschezia
The patient may or may not sense that stool is present in the rectum. Despite prolonged straining, evacuation is tedious or impossible, frequently even for soft stool or enemas.
Patients may complain of anal blockage and may digitally remove stool from their rectum or manually support their perineum or splint the vagina to evacuate.
Actual stool frequency may or may not be decreased.
Diagnosis of Dyschezia
Anorectal manometry and rectal balloon expulsion
Rectal and pelvic examinations may reveal hypertonia of the pelvic floor muscles and anal sphincters. With bearing down, patients may not demonstrate the expected anal relaxation and perineal descent. With excessive straining, the anterior rectal wall prolapses into the vagina in patients with impaired anal relaxation; thus rectoceles are usually a secondary rather than a primary disturbance. Long-standing dyschezia with chronic straining may cause a solitary rectal ulcer or varying degrees of rectal prolapse or excessive perineal descent or an enterocoele.
Anorectal manometry and rectal balloon expulsion, occasionally supplemented by defecatory or magnetic resonance proctography, are necessary to diagnose the condition. (See also the American College of Gastroenterology's 2021 clinical guidelines for the management of benign anorectal disorders.)
Treatment of Dyschezia
Biofeedback
Because treatment with laxatives is unsatisfactory, it is important to assess anorectal functions in patients with refractory constipation.
Biofeedback therapy can improve coordination between abdominal contraction and pelvic floor relaxation during defecation, thereby alleviating symptoms. However, pelvic floor retraining for defecatory disorders is highly specialized and available at select centers only. A collaborative approach (physiotherapists, dietitians, behavior therapists, gastroenterologists) is necessary.
More Information
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
American College of Gastroenterology: Clinical guidelines for the management of benign anorectal disorders (2021)
