Constipation 

Constipation is the most common digestive complaint in the United States. It is a symptom rather than a disease and, despite its frequency, often remains unrecognized until the patient develops sequelae, such as anorectal disorders or diverticular disease.

No widely accepted clinically useful definition of constipation exists. Health care providers usually use the frequency of bowel movements (ie, less than 3 bowel movements per week) to define constipation. However, the Rome criteria, initially introduced in 1988 and subsequently modified twice to yield the Rome III criteria, have become the research-standard definition of constipation.^[1]

According to the Rome III criteria for constipation, a patient must have experienced at least 2 of the following symptoms over the preceding 3 months:

• Fewer than 3 bowel movements per week
• Straining
• Lumpy or hard stools
• Sensation of anorectal obstruction
• Sensation of incomplete defecation
• Manual maneuvering required to defecate

The Rome III criteria also stipulate that a patient should not meet the suggested criteria for irritable bowel syndrome (IBS) and that loose stools are rarely present without the use of laxatives.

For surgical purposes, the most useful definition of constipation is simply a change in bowel habits or defecatory behavior that results in acute or chronic symptoms or diseases that would be resolved with relief of the constipation.

Acute or subacute constipation in middle-aged or elderly patients should prompt a search for an obstructing colonic lesion. Acute constipation must be carefully distinguished from ileus secondary to intra-abdominal emergencies, including infections.

Constipation is frequently chronic, can significantly affect an individual’s quality of life, and may be associated with significant health care costs. It is considered chronic if it occurred for at least 12 weeks (in total, not necessarily consecutively) during the previous year. Chronic constipation may be associated with psychological disturbances, and the reverse is true as well. However, these issues are beyond the scope of this article.

Laboratory evaluation does not play a large role in the initial assessment of the patient. Imaging studies are used to rule out acute processes that may be causing colonic ileus, to evaluate causes of chronic constipation, or to rule out sources of sepsis or intra-abdominal problems. Lower gastrointestinal (GI) endoscopy, anorectal manometry, electromyography (EMG), and balloon expulsion may be used in the evaluation of constipation.

Medical care should focus on dietary change and exercise rather than laxatives, enemas, and suppositories, none of which really addresses the underlying problem. Surgical care is generally restricted to the evaluation of underlying causes; it may also be indicated for the management of acute complications of constipation. Once acute constipation has resolved and the associated medical or surgical conditions have been ruled out, additional inpatient care is rarely indicated.

Constipation is divided, with considerable overlap, into issues of stool consistency (hard, painful stools) and issues of defecatory behavior (infrequency, difficulty in evacuation, straining during defecation). Although hard stools frequently result in defecatory difficulties, soft bulky stools may also be associated with constipation, particularly in elderly patients with anatomic abnormalities and in patients with impaired colorectal motility.

Constipation may originate primarily from within the colon and rectum or may originate externally. Processes involved in constipation originating from the colon or rectum include the following:

• Colon obstruction (neoplasm, volvulus, stricture)
• Slow colonic motility, particularly in patients with a history of chronic laxative abuse
• Outlet obstruction (anatomic or functional) - Anatomic outlet obstruction may derive from intussusception of the anterior wall of the rectum on straining, rectal prolapse, and rectocele; functional outlet obstruction may derive from puborectalis or external sphincter spasm when bearing down, short-segment Hirschsprung disease, and damage to the pudendal nerve, typically related to chronic straining or vaginal delivery
• Hirschsprung disease in children
• Chagas disease

Factors involved in constipation originating outside the colon include poor dietary habits (the most common factor, generally involving inadequate fiber or fluid intake and/or overuse of caffeine or alcohol), medications, systemic endocrine or neurologic diseases, and psychological issues.

Constipation results in various degrees of subjective symptoms and is associated with abnormalities (eg, colonic diverticular disease, hemorrhoidal disease, anal fissures) that occur secondary to an increase in colonic luminal pressure and intravascular pressure in the hemorrhoida l venous cushions.

Nearly 50% of patients with diverticular or anorectal disease, when asked, deny experiencing constipation. On careful questioning, however, nearly all of these patients report having symptoms suggestive of defecatory straining or infrequency, mostly constipation related, although occasionally diarrhea related in patients with irritable bowel or other chronic diarrheal disorders.

The etiology of constipation is usually multifactorial, but it can be broadly divided into 2 main groups: primary constipation and secondary constipation.

Primary constipation

Primary (idiopathic, functional) constipation can generally be subdivided into the following 3 types:

• Normal-transit constipation (NTC)
• Slow-transit constipation (STC)
• Pelvic floor dysfunction (ie, pelvic floor dyssynergia)

NTC is the most common subtype of primary constipation. Although the stool is passing through the colon at a normal rate, patients find it difficult to evacuate their bowels. Patients in this category sometimes meet the criteria for IBS with constipation (IBS-C). The primary difference between chronic constipation and IBS-C is the prominence of abdominal pain or discomfort in IBS. Patients with NTC usually have a normal physical examination.

STC is characterized by infrequent bowel movements, decreased urgency, or straining to defecate. It occurs more commonly in female patients. Patients with STC have impaired phasic colonic motor activity. They may demonstrate mild abdominal distention or palpable stool in the sigmoid colon.

Pelvic floor dysfunction is characterized by dysfunction of the pelvic floor or anal sphincter. Patients often report prolonged or excessive straining, a feeling of incomplete evacuation, or the use of perineal or vaginal pressure during defecation to allow the passage of stool, or they may report digital evacuation of stool.

Secondary constipation

Dietary issues that may cause constipation include inadequate water intake; inadequate fiber intake; overuse of coffee, tea, or alcohol; a recent change in bowel habit paralleled by changes in the diet; and ignoring the urge to defecate. Reduced levels of exercise may play a role as well.

Structural causes of secondary constipation include anal fissures, thrombosed hemorrhoids, colonic strictures, obstructing tumors, volvulus, and idiopathic megarectum.

Systemic diseases that may cause constipation include the following:

• Endocrinologic and metabolic disorders -Hypercalcemia, hyperparathyroidism, hypokalemia, hypothyroidism, pregnancy, and diabetes mellitus (constipation is the most common gastrointestinal problem affecting the diabetic population)
• Neurologic disorders - Stroke, Hirschsprung disease, Parkinson disease, multiple sclerosis, diabetic autonomic neuropathy, spinal cord lesion, head injury, cerebrovascular accident, Chagas disease, and familial dysautonomia
• Connective-tissue disorders -Scleroderma, amyloidosis, and mixed connective-tissue disease

Often, what appears to be acute or subacute constipation may represent a colonic or small bowel ileus from systemic or intra-abdominal infection or other intra-abdominal emergencies. In appropriate settings, this should be addressed and not missed, lest the patient’s condition deteriorate acutely.

Medications that may contribute to constipation include the following:

• Antidepressants (eg, cyclic antidepressants and monoamine oxidase inhibitors [MAOIs])
• Metals (eg, iron and bismuth)
• Anticholinergics (eg, benztropine and trihexyphenidyl)
• Opioids (eg, codeine and morphine)
• Antacids eg, (aluminum and calcium compounds)
• Calcium channel blockers (eg, verapamil)
• Nonsteroidal anti-inflammatory drugs (NSAIDs; eg, ibuprofen and diclofenac)
• Sympathomimetics (eg, pseudoephedrine)
• Many psychotropic drugs^[2]
• Cholestyramine and stimulant laxatives (long-term use) - Although laxatives are frequently used to treat constipation, chronic laxative use becomes habituating and may lead to the development of a dilated atonic laxative colon, which necessitates increasing laxative use with decreasing efficacy
• Inadequate thyroid hormone supplementation

Constipation may be of toxicologic origin, as with lead poisoning.

Psychological issues (eg, depression, anxiety, somatization, and eating disorders) may also contribute to the development of constipation.

United States statistics

Chronic constipation is highly prevalent and affects approximately 15% of persons in the United States.^[3] In 2006, the number of constipation-related physician visits reached 5.7 million, and of these, 2.7 million visits had constipation as the primary diagnosis.^[4] About 2% of the population describes constant or frequent intermittent episodes of constipation.

International statistics

Prevalence of self-reported constipation substantially varies because of differences among ethnic groups in how constipation is perceived. In North America alone, chronic constipation affects approximately 63 million people. Worldwide, approximately 12% of people suffer from self-defined constipation; people in the Americas and the Asian Pacific suffer twice as much as their European counterparts.

A meta-analysis of patients in Europe and Oceania cited prevalence rates as high as 81%, with a general incidence of approximately 17%. Female sex, age, and educational class were strongly associated with prevalence of constipation.^[5]

Age-related demographics

Constipation can occur in all ages, from newborns to elderly persons. An age-related increase in the incidence of constipation has been observed, with 30-40% of adults older than 65 years citing constipation as a problem.^[6] The increased frequency of constipation in adults older than 65 years may reflect a combination of dietary alterations, decreases in muscle tone and exercise, and the use of medications that may result in relative dehydration or colonic dysmotility.^[7] Some researchers suggest that cumulative exposure to environmental neurotoxins may play a role.

In some patients, chronic or repeated pelvic injury (eg, from pregnancies) or the development of anatomic abnormalities (eg, rectal prolapse or rectocele [weakness in the posterior vaginal wall that allows the rectum to prolapse into the vagina upon straining]) may lead to functional outlet obstruction.

Sex-related demographics

In the United States, self-reported constipation and admissions to hospital for constipation are more common in women than in men. The overall female-to-male ratio is approximately 3:1. Women are also more likely to receive care for constipation. The condition is seen fairly frequently during pregnancy and is a common problem after childbirth. Surveys of apparently healthy young men and women demonstrate a slightly higher stool frequency among women.

Race-related demographics

In the United States, the prevalence of constipation is 30% higher among nonwhite populations than among white populations.^[3] Both self-reported constipation and constipation requiring admission to a hospital are more frequent in black people than in white people.

Whereas constipation is less common in Asians, it is more frequent in those who adopt a Western diet.

In contrast, constipation is less frequent among black Africans than white Africans, further suggesting that diet and other environmental factors play an important role.

Most active patients do well with medical management and appropriate dietary management. Recurrence depends on the patient’s long-term compliance to therapy. A small percentage of patients are quite debilitated as a result of constipation. Some patients with functional (primary or idiopathic) constipation (ie, colonic inertia) require total abdominal colectomy with ileorectal anastomosis.

After a careful preoperative workup that includes physical and psychological assessment, patients with outlet obstruction generally respond well to surgical correction and have a good prognosis.

Dyskinesias of the pelvic floor musculature and of the sphincter mechanism may be managed via biofeedback therapy, but the results are mixed.

Patients who are chronically dependent on increasing doses of self-prescribed laxatives are perhaps the most difficult patients to treat. Most such patients can be treated with a combination of fiber, water, and osmotic agents (eg, polyethylene glycol ,sorbitol). However, the need for increasing doses of laxatives and the intermittent use of other agents becomes problematic.

In rare situations in which patients are virtually refractory to laxatives, total abdominal colectomy may be performed after careful workup. Postoperatively, these patients often experience a greatly improved quality of life. A careful preoperative evaluation and a detailed informed consent discussion are required.

Patient education typically involves instructions for improving dietary management. Dietary deficiency requires increased fluid and fiber supplementation for life. For patients who implement recommended dietary changes, the prognosis is excellent.

For patient education resources, see the Esophagus, Stomach, and Intestine Center, as well as Constipation in Adults and Constipation in Children.