Introduction
Background
Constipation is a common symptom, but it often remains unrecognized until the patient develops sequelae, such as anorectal disorders or diverticular disease. Several definitions of constipation have been proposed based on stool frequency in different populations. However, for surgical purposes, the most useful definition of constipation is a change in the bowel habit 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.
Although chronic constipation may be associated with psychological disturbances, the reverse is true as well. However, these issues are beyond the scope of this article.
The definition of constipation includes the following: infrequent bowel movements (typically <3 times per wk), difficulty during defecation (straining during more than 25% of bowel movements or a subjective sensation of hard stools), or the sensation of incomplete bowel evacuation.
Pathophysiology
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 is the end effect of several factors: poor diet, lack of exercise, motility abnormalities, and anatomic defects, along with the patient's expectations and psychological factors.
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. However, nearly all of these patients have symptoms suggestive of defecatory straining or infrequency upon careful questioning.
Frequency
United States
Self-reported constipation is one of the most common GI disorders in the United States. About 2% of the population describe constant or frequent intermittent episodes of constipation.
International
Prevalence of self-reported constipation substantially varies because of differences among ethnic groups in how constipation is perceived.
One meta-analysis depicted prevalence rates as high as 81%, with a general incidence of approximately 17%. Female gender, age, and educational class were strongly associated with prevalence of constipation.1
Mortality/Morbidity
Difficulty in defecation may cause substantial discomfort, abdominal cramping, and a general feeling of malaise.
* Actual or perceived constipation typically results in self-medicating with various laxatives. Although laxatives may correct the acute problem, the chronic use of them leads to habituation, requiring ever-increasing doses that result in drug dependency and, ultimately, a hypotonic laxative colon.
* Acute or chronic episodes of straining may cause acute or chronic hemorrhoidal disease (characterized by pain, itching, or bleeding) or acute hemorrhoidal thrombosis (characterized by intense pain and acute engorgement of 1 or more of the hemorrhoidal columns). Whether constipation actually causes hemorrhoidal disease is controversial. Upon careful questioning, these patients frequently provide a history of recent defecatory difficulties (with the exception of patients in the early postpartum period). Furthermore, conservative management of hemorrhoidal disease is more likely successful when future straining is prevented.
* The passage of hard stools may result in an acute anal fissure, which is a painful tear in the anoderm that may bleed. The regular passage of hard stools and the painful anal spasms during defecation that impinge the hard stools against the fresh wound prevent the anal fissure from healing. In addition to local wound care and analgesia, softening of stools is essential for successful management of an anal fissure.
* Constipation may be one cause of pelvic floor damage in women.2 Using structured questionnaires, Amselem et al determined that 61 out of 596 women (10%) attending a gynecologic clinic had pelvic floor damage. Constipation was present in 19 of the 61 women (31%), rivaling the frequency of obstetric trauma (also 19 women) among these patients. The authors also determined that in the 535 women without pelvic floor damage, 86 of them (16%) had constipation, and 83 of them (15.5%) had obstetric trauma. Employing univariate analysis, Amselem and colleagues reported odds ratios of 2.36 and 2.46 for, respectively, constipation and obstetric trauma associated with pelvic floor damage. Based on their data, the authors suggested that constipation and obstetric trauma are equally important in the development of pelvic floor damage.
Race
* In the United States, both self-reported constipation and constipation requiring admission to a hospital are more frequent in black people than in white people.
* While 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.
Sex
In the United States, self-reported constipation and admissions to hospital for constipation are more common in women than in men. Surveys of apparently healthy young men and women demonstrate a slightly higher stool frequency among women.
Age
* The prevalence of constipation increases exponentially in adults older than 65 years. This may reflect a combination of dietary alterations, decreases in muscle tone and exercise, and the use of medications, which may result in relative dehydration or colonic dysmotility.3
* Some researchers have suggested that cumulative exposure to environmental neurotoxins may play a role in the age-related increase in the prevalence of constipation.
* In some patients, chronic or repeated pelvic injury (eg, from pregnancies) or the development of anatomic abnormalities (eg, rectal prolapse, rectocele [weakness in the posterior vaginal wall allowing the rectum to prolapse into the vagina upon straining]) may lead to functional outlet obstruction.
Clinical
History
Basing the diagnosis of constipation on simply asking the patients whether they are constipated is associated with the marked underreporting of the problem in patients who have physical evidence of constipation, such as the presence of hemorrhoidal disease.4
* History should begin with a detailed inquiry into the patient's normal pattern of defecation, the frequency with which the current problem differs from the normal pattern (eg, "missing a day"), the perceived hardness of the stools, whether the patient strains in order to defecate, and any other symptoms the patient may be experiencing.
o An inquiry concerning the amount of time spent on the toilet while waiting to defecate may also be illuminating. Patients should be asked to describe in detail what happens when they try to defecate and what maneuvers (pharmacological or physical) they have used to facilitate this process. These questions may suggest chronic laxative abuse or less common causes, such as colonic outlet obstruction.
o The duration of the problem is important. In adolescents or young adults, the duration of the problem may differentiate congenital defects from acquired causes. Neoplastic obstruction is less likely in patients older than 50 years who have had symptoms for at least 2 years.
o Questions regarding the onset of constipation may provide useful etiological information, either in terms of changes in diet, new medications, or associated psychosocial difficulties at that time.
* In addition to defining the nature of the patient's bowel habit, the factors that are likely to be responsible for the abnormal bowel habit should be delineated. Most patients who are constipated consume either too little fiber or too little water; therefore, assessing the patient's diet is useful. For acute changes in the bowel habit, a parallel dietary change should be ascertained. Learning how much fluid and what types of fluids the patient drinks on an average day is important.
o Epidemiological studies have clearly established a link between coffee consumption and worsening constipation.
o The diuretic effects of coffee, tea, and alcohol are likely counterproductive.
o Milk products may cause constipation in some individuals.
* The state of patients' bowel motility represents a balance between factors that promote motility and those that inhibit it.
o The most important influencing factor is exercise, which stimulates bowel motility. Conversely, the use of narcotics, antipsychotic agents, and other constipating medications reduce motility.
o Diuretics or substantial amounts of coffee, tea, or alcohol decrease available water to the colon.
o Chronic laxative abuse also causes refractory constipation.
* If the patient shows evidence of diseases or symptoms associated with constipation, such as diverticular disease, hemorrhoids, anal fissures, or fistula-in-ano, delineating these conditions historically and determining the nature of any previous treatment for these conditions is appropriate. For instance, patients with hemorrhoids may neglect to mention that they were previously treated for this problem or that they have been receiving medications for constipation for several years.
* Rectal bleeding should be taken seriously and evaluated carefully, particularly in patients older than 50 years or with a family history of colorectal disease.
o Patients with hemorrhoids may also have rectosigmoid cancer. Both cancer and hemorrhoids can produce bright red blood from the rectum.
o Most patients older than 50 years or with a family history of colorectal disease should be screened for colorectal cancer with at least a sigmoidoscopic examination.
* Finally, the evaluation should include the patient's description of the act of defecation.
o Pain during defecation might suggest a fissure or tenesmus from a rectal tumor.
o Painless inability to pass an otherwise soft stool suggests a rectal outlet obstruction.
* Neurological or endocrine disorders also can cause constipation.
o Most notably, diabetes may be associated with chronic dysmotility.
o Patients with hypothyroidism may exhibit decreased motility and slow transit times.5
o Patients with panhypopituitarism, pheochromocytoma, or multiple endocrine neoplasia 2B are also at risk of developing constipation.
o When no other cause can be determined, a careful endocrine review is particularly important for patients with a recent onset of constipation and for patients who are refractory to conservative treatment.
o Similarly, central nervous system diseases, such as Parkinson disease, multiple sclerosis, stroke, CNS syphilis, and spinal injury or tumors, may cause constipation and should be considered in the patient's history and evaluation.
* Some cases of constipation may have a psychogenic component because constipation is a frequent somatic expression of psychological distress. Alternately, constipation may result in psychological disturbances.
o A history of sexual abuse is observed with unusual frequency in patients who are chronically constipated, particularly those with anismus.
o A history of other psychological abnormalities is often found, particularly among patients who are refractory to medical treatment and have normal bowel transit times and normal results from anorectal studies. Such factors should be gently explored in patients in whom the first-line conservative treatment has failed.
o Psychiatric referral may be appropriate in such patients after medical evaluation and therapy has been exhausted or if gentle questioning reveals some unexpected information.
Physical
In addition to the general evaluation, the abdomen, pelvis, and rectum, specifically, should be physically examined. Both the cause of constipation and its effects should be sought.4
* Abdominal examination
o Abdominal distention or masses may indicate the presence of colonic stools or tumors.
o Large abdominal wall hernias, especially ventral hernias, may interfere with the generation of adequate intra-abdominal pressure that is required for the initiation of defecation.
o Rarely, a left-sided sliding inguinal hernia with an incarcerated sigmoid colon may cause difficulties in bowel movements.
o Conversely, the once-held belief was that elderly patients with new inguinal hernias should be assumed to have occult constipation due to partially obstructing colonic neoplasms and that those patients required colorectal cancer screening. The requirement for colorectal cancer screening in such patients remains controversial, and the pathophysiology underlying a link between colonic neoplasms and hernias is unknown because the lesions detected on screening are early lesions and are unlikely to have caused constipation.
* Pelvic examinations in women should specifically address the posterior vaginal wall, with attention to any evidence of internal prolapse or rectocele.
o This region should be palpated while the patient is at rest and then while she is straining to defecate.
o Many women with rectocele do not experience constipation. Good surgical results are not guaranteed, and a thorough preoperative workup to rule out other potential causes of constipation should always be performed.
* Perform a complete anorectal examination to determine the cause of constipation and to assess its effects.
* Causes of constipation that may be defined on rectal examination include the following:
o Anal fissure, particularly in children who retain their feces in order to avoid painful defecation
o Anal stenosis
o Partially obstructing rectal masses
o Rectal prolapse: The rectal prolapse may be either external or internal. The anus should be carefully examined for prolapse at rest and during a Valsalva maneuver. Care should be taken to distinguish a true full-thickness rectal prolapse from a mucosal prolapse, which is unlikely to cause constipation. Asking the patient to perform a Valsalva with the examining finger in the rectum in order to seek evidence of an internal prolapse may be worthwhile, although this is a relatively insensitive way to diagnose a prolapse. In contrast to inguinal hernias, rectal prolapses are typically related to constipation. At least 1 retrospective study has demonstrated a strong association between rectal prolapse and rectosigmoid neoplasms in patients older than 50 years. Sigmoidoscopy is probably indicated for these patients.
* In addition to delineating the cause of constipation, an anorectal examination should be used to determine the effects of the constipation.
o The presence of fissures or fistulae, evidence of scars from previous perirectal abscess drainages or other surgeries, and the nature of the patient's hemorrhoidal columns should be characterized.
o Enlarged hemorrhoids do not require treatment unless they cause symptoms.
* Although the effectiveness of fecal occult blood testing has been hotly debated, performing such a test following a rectal examination in patients older than 50 years is probably worthwhile.
o The presence of blood in the stool requires further evaluation.
o Never assume that the patient is bleeding from hemorrhoids or fissures until other sources of bleeding have been ruled out.
* A component of a complete physical evaluation of the patient should be to look for evidence of systemic diseases contributing to constipation. Such systemic diseases include the following:
o Endocrine dysfunctions, such as hypothyroidism, hypopituitarism, or diabetes mellitus
o Neurologic abnormalities, such as brain or spinal cord injury, peripheral neuropathy, multiple sclerosis, or Parkinson disease
Causes
Constipation may originate primarily from within the colon and rectum or may originate externally.
* Causes of constipation directly attributable to the colon or rectum
o Left colon obstruction (neoplasm, volvulus, stricture)
o Slow colonic motility, particularly in patients with a history of chronic laxative abuse
o Hirschsprung disease
o Chagas disease
o Outlet obstruction
* Outlet obstruction may be anatomical or functional. Characteristics of outlet obstruction include the following:
o Patients have difficulty evacuating bowels despite straining, often even with soft stools.
o Anatomic outlet obstruction may be due to intussusception of the anterior wall of the rectum on straining, rectal prolapse, and rectocele.
o Functional causes of outlet obstruction include puborectalis and/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.
* Causes of constipation outside the colon
o Poor dietary habit (most common)
o Medications
o Systemic endocrine or neurologic diseases
o Psychological factors
* Dietary issues
o Inadequate water intake
o Inadequate fiber intake
o Overuse of coffee, tea, or alcohol
o Recent change in bowel habit paralleled with changes in the diet
* Medications that may contribute to constipation include the following:
o Narcotics
o Iron supplements
o Nonmagnesium antacids
o Calcium-channel blockers
o Inadequate thyroid hormone supplementation
o Many psychotropic drugs6
o Anticholinergic agents
o 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 requires increasing laxative use with decreasing efficacy.
* Systemic diseases
o Endocrine dysfunctions, most commonly hypothyroidism
o Neurologic dysfunction, including diabetic autonomic neuropathy, spinal cord injury, head injury, cerebrovascular accident, multiple sclerosis, and Parkinson disease
o Often, what appears to be acute or subacute constipation may represent a colonic ileus from systemic or intra-abdominal infection or other intra-abdominal emergencies.Differential Diagnoses
Abdominal Hernias
Ileus
Anxiety Disorders
Intestinal Motility Disorders
Appendicitis
Intestinal Pseudo-obstruction: Surgical Perspective
Chagas Disease (American Trypanosomiasis)
Intra-abdominal Sepsis
Colon Cancer, Adenocarcinoma
Irritable Bowel Syndrome
Colonic Obstruction
Megacolon, Toxic
Crohn Disease
Multiple Endocrine Neoplasia, Type 2
Depression
Ogilvie Syndrome
Diverticulitis
Hypopituitarism (Panhypopituitarism)
Hypothyroidism
Other Problems to Be Considered
Psychological causes
Workup
Laboratory Studies
* Laboratory evaluation does not play a large role in the initial assessment of the patient.
* Check thyroid-stimulating hormone levels to rule out hypothyroidism in patients refractory to dietary management.
* Determine serum electrolyte profile, including potassium, calcium, glucose, and creatinine, in patients with recent-onset constipation to assess an acute electrolyte imbalance and in chronically constipated patients for whom initial medical treatment has failed.
* Fecal occult blood should be tested in chronically constipated middle-aged or elderly adults to assess an obstructing neoplasm of the colon.
* Leukocyte count is useful for patients presenting with abdominal pain or fever or providing any indication that the constipation is secondary to an ileus. This may lead to further, more aggressive evaluation.
Imaging Studies
* Imaging studies are used to rule out acute processes that may be causing colonic ileus or to evaluate causes of chronic constipation.
* In patients with acute abdominal pain, fever, leukocytosis, or other symptoms suggesting possible systemic or intra-abdominal processes, imaging studies are used to rule out sources of sepsis or intra-abdominal problems.
o Order an upright chest roentgenogram and a flat and upright abdominal film. The abdominal film may reveal a colon full of stools, confirming the diagnosis of obstipation.
o Abdominal CT scan may be indicated to further evaluate the possibility of an intra-abdominal abscess.
o Acute constipation in the setting of an empty rectal vault and a proximal colon that is dilated with air or stool suggests large bowel obstruction, which should be further evaluated via Gastrografin enema or lower GI endoscopy.
o Gastrografin enema has the advantage of acting as an osmotic laxative, which may aid in the evacuation of the colonic contents.
* Air contrast barium enema is useful to assess the possibility of an obstructing colon cancer, intermittent volvulus, or colonic stricture in the setting of chronic constipation.
o A barium study is preferable to Gastrografin for patients who do not present with an acute process. On the other hand, Gastrografin is preferable for patients with an acute abdomen because this prevents the risk of extravasation of barium into the peritoneal cavity through a perforated diverticulum or colon cancer.
o In patients with suspected colonic obstruction, the author prefers to use colonoscopy instead of barium enema, but either may suffice.
* Defecography should be performed if an obstruction is suspected at the level of the anal canal.
o Fill the rectosigmoid with barium paste and fluoroscopically observe the act of defecation.
o This test may demonstrate alterations in the anorectal angle during defecation, presence of pelvic floor weakness,2 or transient rectal prolapse or intussusception.
* Controlled pressure-based rectal distension with fluoroscopic rectal imaging to measure the rectal diameter at the minimal distension pressure may be useful in identifying idiopathic megabowel in the absence of an organic cause of other problems.7
* Conversely, colonic transit time should be determined in patients suspected to have colonic motility disorder.
o Accomplish this by observing the passage of orally administered radiopaque markers via daily abdominal roentgenograms.
o Record the time taken for the passage of the markers and the site where they appear to be retained.
o A patient with outlet obstruction tends to retain the markers in the left colon and sigmoid, while a patient with colonic dysmotility may retain the markers throughout the colon.
Procedures
* Lower GI endoscopy, anorectal manometry, electromyography, and balloon expulsion may be used in the evaluation of constipation.
* Lower GI endoscopy is useful in patients who are acutely constipated if large bowel obstruction is suspected based on an empty rectal vault and a distended proximal colon.
o Colonoscopy should not be performed if perforation or acute diverticulitis or other infectious processes are suspected because of the risk of worsening intra-abdominal contamination caused by colonic distension during the procedure.
o In the acute setting, bowel preparation is either not used or, at the most, 1-2 gentle enemas are used.
o Rigid endoscopy may be used in an urgent situation when flexible endoscopy is not available.
o Flexible endoscopy is generally preferred over rigid endoscopy because the former is more comfortable for the patient, provides a better view for the endoscopist, and permits access to more of the colon.
o Advance the flexible endoscope into the rectosigmoid until the site of the obstruction is reached or until the splenic flexure is identified, which suggests the absence of a rectosigmoid obstruction.
o If the initial sigmoidoscopy reveals no abnormal findings or if the constipation is more chronic, the patient should subsequently undergo a standard oral bowel preparation and either colonoscopy (the author's preference) or air contrast barium enema to more fully evaluate the remainder of the colon.
o Deep rectal biopsy, sometimes with double or triple bite techniques, may be used to diagnose Hirschsprung disease.
* Anorectal manometry documents several parameters. Interpreting the results of this test is complex and varies with the center performing the test. Consult a specialist familiar with the local testing facilities. These parameters include the following:
o External anal sphincter and puborectalis muscle function
o Reflex relaxation of the internal sphincter when the rectum is distended
o Coordination of these muscles during the bear-down phase of defecation
o Anorectal pressures during these events
o The threshold at which rectal distension is perceived
* Electromyography
o This study documents paradoxical external sphincter or puborectalis spasm during defecation, consistent with the diagnosis of anismus.
o It is useful during subsequent biofeedback training because the patient is taught to relax these muscles.
* Balloon expulsion
o A balloon filled with varying amounts of water is rectally inserted. The patient is asked to expel the balloon.
o Decreased ability to expel a balloon filled with 150 mL of water suggests decreased defecatory ability.
* Manual disimpaction and transrectal enemas may be used after any critical illness associated with constipation has been ruled out.
Histologic Findings
Findings include the histology of any obstructing colonic lesion (eg, neoplasms, strictures from Crohn disease, diverticulitis, ischemia) and the agangliosis of Hirschsprung disease.Treatment
Medical Care
* After serious illnesses have been ruled out, the medical care of the acutely constipated patient involves a combination of enemas and laxatives, preceded by manual disimpaction of stools if necessary. This is then followed by elective evaluation of the causes of the constipation.
o In the acute situation with a patient at low risk who usually is not constipated, no further evaluation is necessary.
o Consider sigmoidoscopy, colonoscopy, or barium enema for colorectal cancer screening in patients older than 50 years.
o Counsel the patient regarding the appropriate dietary prophylaxis with follow-up visits on an outpatient basis. If the patient experiences further episodes of constipation, a more detailed evaluation may then become appropriate (see Workup).
* Medical care should focus on dietary change and exercise rather than laxatives, enemas, and suppositories, none of which really addresses the underlying problem.
o The patient is at a high risk to become dependent on laxatives and develop a laxative colon.
o If conservative measures fail and the patient is clearly compliant with the advice, a more detailed evaluation should be performed (see Workup).
Surgical Care
* Surgical care is generally restricted to the evaluation of underlying causes, such as large bowel obstruction, volvulus, or intra-abdominal infection or ischemia.
* Surgical care may also be indicated for the management of acute complications of constipation, such as hemorrhoidal thrombosis.
* Surgery may occasionally play a role in the management of rectal outlet obstruction (eg, rectocele, rectal prolapse, internal rectal intussusception) or in patients with a hypomotile (laxative) colon who are refractory to medical treatment. In the former case, treatment is directed at the cause of the outlet obstruction. In the latter case, total abdominal colectomy may be indicated. This may be less morbid if performed laparoscopically.8,9 In both cases, thorough preoperative evaluation is essential to rule out other medically treatable causes or potentiating factors. These patients may also have an underlying psychological cause for their ailment, and addressing this is important before irreversible surgical interventions are contemplated.
* Benign outlet obstruction due to prolapse may be managed by stapled transanal rectal resection or anopexy.10,11 Laparoscopic ventral rectopexy has also been advocated for this problem, although this may be more invasive.12
* There is increasing interest in the use of sacral nerve stimulation in carefully selected patients with severe refractory constipation. In such patients, temporary percutaneous stimulation is typically used for 2-3 weeks to seek benefit, but such trials may not always predict success with permanently implanted nerve stimulators.13,14 This technology seems promising but awaits further experience to delineate its indications, risks, and benefits.
Consultations
* Surgical consultation is indicated when a suspicion exists of large bowel obstruction or colonic ileus secondary to an acute intra-abdominal process.
* Surgical consultation also is indicated for anorectal complications of constipation or for surgical correction of the underlying cause.
o Symptomatic hemorrhoids and anal fissures represent complications of constipation until proven otherwise.
o Acute hemorrhoidal thrombosis requires urgent surgical consultation for evacuation of the clot and relief of pain.
o For prolonged chronic hemorrhoids, a trial of aggressive medical treatment should be given prior to surgical consultation (fiber supplementation, increased water intake, exercise, decreased coffee and alcohol intake, sitz baths, local symptomatic treatment).
o Similarly, acute anal fissures should be managed conservatively because most respond well to aggressive programs of sitz baths, stool softeners, and local anesthetic ointment.
o Chronic nonhealing fissures may be managed with topical nitroglycerin or botulinum toxin injections with reasonable success. However, the long-term recurrence rate after such therapy has yet to be established.
o Many of these patients may require surgical sphincterotomy or anal dilation.
o A colorectal surgeon should be consulted for patients with chronic fissures to evaluate the need for surgical intervention and to consider biopsy of the fissure to rule out malignancy.
o Perirectal abscess and fistula-in-ano may be related to chronic constipation. These complications do not respond to medical management and require surgical referral.
* A consultation with a gastroenterologist is necessary to rule out other colonic processes and to assist with the long-term program of stool softener and laxative use in patients who do not respond to simple measures.
* Either a gastroenterologist or a surgeon may be consulted for lower GI endoscopy, depending on local referral patterns and the availability of expertise.
* Psychological or psychiatric consultation may be appropriate prior to surgical intervention to treat patients with potential or identified psychological issues.
* In adults, surgical or gastroenterologic consultation may be required to differentiate benign solitary rectal ulcers from rectal malignancy.
Diet
The key to treating most patients with constipation is correction of dietary deficiencies. These generally involve increasing fiber and fluid intake and decreasing the use of constipating agents, such as milk products, coffee, tea, and alcohol.
* Dietary fiber
o Dietary fiber is available in diverse natural sources, such as fruits, vegetables, and cereals. It is nutritionally superior to supplementation with purified fiber. However, advising patients to eat more fruits and vegetables is frequently unsuccessful, at least in American patients. Conversely, American patients respond reasonably well to prescriptions and often seek them. Prescribing a fiber supplement, such as wheat, psyllium, or methylcellulose, is often useful.
o Many of the available products vary substantially in their potency. For instance, sugar-free Metamucil has twice the potency of standard Metamucil on a volume basis because the latter is half sugar. Pharmaceutical companies may argue that one type of fiber is better tolerated or more effective than another. This may not make much difference in treatment or in fiber tolerance in most patients as long as the fiber supplementation doses start low and are slowly titrated upward. Theoretical considerations suggest that the use of a fermentable fiber, which increases short chain fatty acid concentrations in the colonic lumen, may have other health benefits (as opposed to methylcellulose). However, this remains controversial and awaits further exploration.
o Because no convincing reason exists to pick one product over another, a single brand of choice should be prescribed until the patient's constipation resolves. The patient may then switch to generic or other brands with appropriate dose adjustments. The author's experience has been that some patients have preferences based on the taste of the product or other subjective reasons. In particular, rare patients who cannot tolerate fermentable fiber supplementation because of resulting gas or bloating may do better with methylcellulose, while others find the quality of the stool, taste preferences, or both favoring psyllium supplementation.
o To avoid patient noncompliance due to the development of cramping and bloating that accompany changes in dietary fiber, fiber supplementation should be started at a low subtherapeutic dose and titrated upwards on a weekly basis until the desired effect is achieved. Patients should continue to increase the dose on a weekly basis until they experience daily bowel movements with no straining or until they achieve the maximum dose.
o Patients should be cautioned that these products are not laxatives, will not induce a bowel movement, and must be taken daily regardless of their perceived need.
o Patients may increase or decrease their dose on a week-to-week basis. In particular, the author advises patients who have arrived at what they believe to be an appropriate and successful dose to increase the dose one additional step for at least a week and then back down if they wish. Some patients actually prefer the higher dose. To ensure long-term compliance, the author believes that patients should titrate the doses in case of changes in potency between fiber supplement brands or changes in diet, fluid intake, or exercise.
o Patients should be cautioned that, although various stool softeners, such as docusate sodium, appear much more palatable than fiber, they are not suitable for long-term use. Tachyphylaxis to stool softeners develops over time.
* Fluid intake
o Fluid intake is the key to treatment. Patients should be advised to drink at least 8 glasses of water daily. Counseling may be required to achieve this goal.
o Milk and milk products should be minimized if these prove constipating.
o In some patient populations, most consumed fluids consist of coffee, tea, and alcohol. Patients should understand that this practice is counterproductive because of the diuretic effects of these products. The author usually recommends that patients decrease consumption of coffee, tea, and alcohol as much as possible, and they should consume an extra glass of water for every drink of coffee, tea, or alcohol.
* Failure to control constipation on a regimen of fiber supplementation and water should prompt the analysis of patient compliance and the search for other physical causes, such as altered colonic transit time, outlet obstruction, and psychological causes. The author's experience is that early failures usually reflect inadequate water intake, while recidivism months to years later usually corresponds to a patient having decided that the fiber supplementation is no longer necessary. Counsel patients in advance to avoid these inappropriate decisions.
* In selected patients who comply with but do not successfully treat their constipation with a trial of a high fiber, high water diet, a trial of a very low residue or even a liquid diet may be appropriate.
o Such a regimen is most successful in patients with outlet obstruction who are not candidates for surgical correction and in patients whose presentation is more characteristic of irritable bowel syndrome with a chief complaint of abdominal pain.
o A low residue diet may be effective in the latter group of patients if thorough mechanical cleansing of the bowel, such as is done for diagnostic endoscopy or barium enema, temporarily relieves their symptoms.
Activity
Although some controversy exists about the effectiveness of exercise in constipation treatment, encouraging as much aerobic exercise as possible seems reasonable. Even brisk walking may help stimulate bowel motility and, certainly, is unlikely to hurt most patients.
Medication
Medications to treat constipation include bulk-forming agents (fibers), emollient stool softeners, and rapidly acting lubricants and laxatives. Fiber is the best medication for long-term treatment.
Emollient stool softeners are easier to use, but they lose their effectiveness with chronic administration. These drugs are best used for prophylaxis in a short-term setting, such as in patients receiving a postoperative narcotic prescription.
Rapidly acting lubricants and laxatives, including over-the-counter products, are often used to treat acute and chronic constipation. However, their use should be limited for acute episodes because of the long-term risk of habituation, toxicity, or both.
Conversely, patients must understand that bulk-forming agents do not generally work rapidly and have to be used on a long-term basis.
See related CME at Methylnaltrexone Appears Effective for Severely Ill Patients With Opioid-Induced Constipation.
Bulk agents
Chronic prophylaxis, treatment of constipation, or both in patients without anatomic outlet obstruction.
Psyllium (Metamucil, Fiberall)
Dosages vary depending on whether the preparations contain sugar or are sugar-free (the former are 50% sugar). They must be taken with water or they may cause obstruction.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
15-60 g/d PO with at least 8 glasses of water
Pediatric
7.5-15 g/d PO with at least 4 glasses water
* Dosing
* Interactions
* Contraindications
* Precautions
May reduce bioavailability of medications if taken within 30-60 min of fiber supplements because of adsorption to fiber; may decrease absorption of salicylates, nitrofurantoin, tetracyclines, and diuretics
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; fecal impaction, intestinal obstruction, or undiagnosed abdominal pain
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Use caution in patients with intestinal adhesions, ulcers, or bowel stenosis
Methylcellulose (Citrucel)
Theoretically, nonfermentable, less–gas-producing products are better tolerated than psyllium. Occasionally, patients who cannot tolerate one preparation may do well with another product.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
15-60 g/d fiber PO with at least 8 glasses of water
Pediatric
7.5-15 g/d PO with at least 4 glasses of water
* Dosing
* Interactions
* Contraindications
* Precautions
May reduce bioavailability of medications if taken within 30-60 min of fiber supplements because of adsorption to fiber; may decrease absorption and effects of salicylates, nitrofurantoin, tetracyclines, and diuretics
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; fecal impaction, intestinal obstruction, or undiagnosed abdominal pain
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
A - Fetal risk not revealed in controlled studies in humans
Precautions
Use caution in patients with intestinal adhesions, ulcers, or stenosis
Emollient stool softeners
Prophylaxis against constipation in acute and subacute settings.
Docusate sodium (Colace)/Docusate calcium (Surfak)
Indicated for patients who should avoid straining during defecation. Allows incorporation of water and fat into stools, causing stools to soften. Tachyphylaxis with long-term use. Effective acutely. Does not induce defecation.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
50-360 mg/d PO
Pediatric
25-180 mg/d PO
* Dosing
* Interactions
* Contraindications
* Precautions
Decreases the effect of warfarin and increases the effect of phenolphthalein
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; nausea, vomiting, or acute abdominal pain
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studies in humans; may use if benefits outweigh risk to fetus
Precautions
Prolonged use of medication may result in electrolyte imbalance
Emollient stool softeners in combination with stimulants
Emollient stool softeners cause stool to soften. Stimulants increase peristaltic activity in the GI.
Docusate sodium and casanthranol combination (Peri-Colace, Diocto-C, Silace C)
Docusate sodium allows incorporation of water and fat into stool causing stool to soften.
Casanthranol is an anthraquinone stimulant hydrolyzed by colonic bacteria into active compound. Usually produce action 8-12 h after administration.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
1-4 cap/d or tab/d PO
Alternatively, 5-60 mL/d PO if syrup or emulsion given
Pediatric
<6 years: Not recommended
>6 years: Administer as in adults
* Dosing
* Interactions
* Contraindications
* Precautions
Decreases effects of warfarin and increases effects of phenolphthalein
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; nausea, vomiting, GI bleeding, appendicitis, congestive heart failure, fecal impaction, appendicitis, nausea, vomiting, or acute abdominal pain
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studies in humans; may use if benefits outweigh risk to fetus
Precautions
Excessive use may lead to electrolyte imbalance, osteomalacia, steatorrhea, cathartic colon
Saline laxatives
Acute treatment of constipation in absence of bowel obstruction.
Magnesium hydroxide (Phillips Milk of Magnesia)
Causes osmotic retention of fluid, which distends colon and increases peristaltic activity; promotes emptying of bowel.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
2.4-4.8 g/day PO qd or in divided doses
Pediatric
1.2-2.4 g/day PO qd or in divided doses
* Dosing
* Interactions
* Contraindications
* Precautions
Decreases effects of tetracyclines, digoxin, indomethacin, and iron salts
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; colostomy, ileostomy, renal failure, fecal impaction, and appendicitis
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Caution in severe renal impairment
Magnesium citrate (Evac-Q-Mag)
Causes osmotic retention of fluid, distending the colon and increasing peristaltic activity; promotes emptying of bowel. Works within 3 h PO or 15 min PR. May cause electrolyte imbalance, especially in young children or patients with renal insufficiency.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
11-18 g/day PO qd or in divided doses
Pediatric
5.5-9 g/day PO qd or in divided doses
* Dosing
* Interactions
* Contraindications
* Precautions
Decreases effects of tetracyclines, digoxin, indomethacin, and iron salts
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; colostomy, ileostomy, renal failure, fecal impaction, and appendicitis
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Caution in severe renal impairment
Magnesium sulfate
Causes osmotic retention of fluid, which distends the colon and increases peristaltic activity; promotes emptying of bowel.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
10-30 g/day PO qd or in divided doses
Pediatric
5-15 g/day PO qd or in divided doses
* Dosing
* Interactions
* Contraindications
* Precautions
Concurrent use with nifedipine may cause hypotension and neuromuscular blockade; may increase neuromuscular blockade seen with aminoglycosides and potentiate neuromuscular blockade produced by tubocurarine, vecuronium, and succinylcholine; may increase CNS effects and toxicity of CNS depressants and betamethasone, and increase cardiotoxicity of ritodrine
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; heart block, Addison disease, myocardial damage, or severe hepatitis
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
A - Fetal risk not revealed in controlled studies in humans
Precautions
Magnesium may alter cardiac conduction leading to heart block in digitalized patients; respiratory rate, deep tendon reflex, and renal function should be monitored when electrolyte is administered parenterally; caution when administering magnesium dose since may produce significant hypotension or asystole; in overdose, calcium gluconate, 10-20 mL IV of 10% solution, can be given as antidote for clinically significant hypermagnesemia
Lubricant laxatives
Acute or subacute management of constipation; lubricate intestine and facilitate passage of stool by decreasing water absorption from intestine.
Mineral oil (Fleet, Zymenol)
More gentle than some other rapidly acting laxatives. Generally works within 8 h. Long-term use is accompanied by concerns of lipid pneumonia, lymphoid hyperplasia, and foreign body reactions.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
15-45 mL PO as 1-time dose or qd or as retention enemas
Pediatric
1-4 tsp/d (5-20 mL) PO
* Dosing
* Interactions
* Contraindications
* Precautions
Decreases effect of docusate sodium and may decrease absorption of warfarin, oral contraceptives, and fat-soluble vitamins
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; patients who are aspiration prone
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studies in humans; may use if benefits outweigh risk to fetus
Precautions
Should not be taken within 2 h of vitamins or meals; prolonged administration may produce deficiency of fat-soluble vitamins; do not administer with food or meals because may cause aspiration leading to lipid pneumonitis
Osmotics
Useful for long-term treatment of constipated patients with slow colonic transit who are refractory to dietary fiber supplementation.
Lubiprostone (Amitiza)
Locally acting chloride channel activator that enhances a chloride-rich intestinal fluid secretion without altering sodium and potassium concentrations in the serum. Specifically activates C1C-2, an apical membrane in the human intestine. Increases intestinal fluid secretion to assist in GI motility, thereby decreasing symptoms of chronic idiopathic constipation (eg, abdominal pain, bloating, straining, hard stools).
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
24 mcg PO bid with food
Pediatric
Not established
* Dosing
* Interactions
* Contraindications
* Precautions
Data limited; none reported
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; history of mechanical GI obstruction; severe diarrhea
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
C - Fetal risk not established in humans; use if benefits outweigh risk to fetus
Precautions
Common adverse effects include headache, nausea, diarrhea, abdominal pain, and abdominal distension; discontinue if diarrhea persists
Lactulose (Cephulac, Cholac, Constilac, Karo Syrup [for babies])
Produces osmotic effect in the colon, resulting in bowel distention and stimulation of peristalsis.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
20-30 g (30-45 mL) PO q1-2h; adjust dose slowly to produce 2-3 soft stools daily
Alternatively, 200 g diluted with 700 mL of water or NS via rectal balloon catheter and retain 30-60 min q4-6h
Pediatric
5 g/d (7.5 mL) PO after breakfast
* Dosing
* Interactions
* Contraindications
* Precautions
Decreases effects of neomycin, laxatives, and antacids
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; patients that require a galactose diet
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Caution in diabetes mellitus; patients should be monitored for electrolyte imbalance
Sorbitol
Hyperosmotic laxative that has a cathartic action in the GI tract.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
PO: 30-150 mL of a 70% solution
Enema: 120 mL as 25-30% solution
Pediatric
<2 years: Not recommended
2-11 years: 2 mL/kg PO of 70% solution
>12 years: Administer as in adults
* Dosing
* Interactions
* Contraindications
* Precautions
Reduces effectiveness of other drugs when concomitantly administered
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; anuria
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studies in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in severe cardiopulmonary or renal impairment and in patients unable to metabolize sorbitol; should not be used for bowel preparation for colonoscopy and polypectomy because it produces inflammable gases
Polyethylene glycol solution (Miralax)
Typically used in large volumes for bowel preparation and washout prior to surgical or endoscopic procedures. Now being used in smaller volumes as an osmotic (but not hyperosmotic) agent.
In theory, less risk of dehydration or electrolyte imbalance with isotonic polyethylene glycol compared with hypertonic sugar solutions. The laxative effect is generated because polyethylene glycol is not absorbed and continues to hold water by osmotic action through the small bowel and the colon, resulting in mechanical cleansing.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
17 g/d PO in 8 oz of water
Pediatric
Not established
* Dosing
* Interactions
* Contraindications
* Precautions
Reduces effectiveness and absorption of oral medications
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; colitis, megacolon, bowel perforation, gastric retention, or bowel obstruction
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studies in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in ulcerative colitis
Stimulant laxatives
These agents are commonly used to treat acute constipation and are the most common class of laxatives used chronically by individuals using over-the-counter products. The latter represents an inappropriate choice, at least as first- or second-line therapy, given concerns about development of tolerance.
Senna (Senokot, Ex-Lax, Senexon, Senna-Gen)
Anthraquinone is hydrolyzed by colonic bacteria into its active compound. More potent than cascara sagrada and results in considerably more abdominal pain. Usually produces its action 8-12 h after administration.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
0.12-0.25 g/d PO
Pediatric
<6 years: Not recommended
>6 years: Administer as in adults
* Dosing
* Interactions
* Contraindications
* Precautions
Decreases effect of anticoagulants
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; nausea, vomiting; GI bleeding; appendicitis; congestive heart failure; fecal impaction
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Excessive use may lead to electrolyte imbalance, osteomalacia, steatorrhea, cathartic colon
Bisacodyl (Bisac-Evac, Bisco-Lax, Dulcolax, Dacodyl)
Stimulates peristalsis by possibly stimulating the colonic intramural neuronal plexus. Alters water and electrolyte secretion, resulting in net intestinal fluid accumulation and laxation. Provokes defecation within 24 h and may cause abdominal cramping.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
5-15 mg PO as single dose
10 mg PR as single dose
Pediatric
<6 years: Not established
>6 years: 5-10 mg (0.3 mg/kg) PO hs or before breakfast
* Dosing
* Interactions
* Contraindications
* Precautions
Decreases effect of warfarin and antacids
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; abdominal pain, nausea, or vomiting; GI obstruction
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studies in humans; may use if benefits outweigh risk to fetus
Precautions
Caution during pregnancy and lactation
Cascara sagrada
Irritates the intestinal mucosa, resulting in increased colonic motility and alteration in fluid and electrolyte secretion.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
5-6 mL or 1 tab PO hs
Pediatric
Infants: 0.5-1.5 mL/d PO prn
2-11 years: 1-3 mL/d PO prn
* Dosing
* Interactions
* Contraindications
* Precautions
Decreases the effect of anticoagulants
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; nausea, vomiting; GI bleeding; appendicitis; congestive heart failure; fecal impaction
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Excessive use may lead to electrolyte imbalance, osteomalacia, steatorrhea, cathartic colon
Castor oil (Alphamul, Emulsoil, Neoloid, Purge)
Reduced to ricinoleic acid. It decreases net absorption of fluid and electrolytes and stimulates peristalsis. Acts on the small intestine.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
15-60 mL PO once
Pediatric
5-10 mL PO once
* Dosing
* Interactions
* Contraindications
* Precautions
None reported
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; nausea, vomiting; fecal impaction; GI bleeding; appendicitis; congestive heart failure; abdominal pain
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
X - Contraindicated; benefit does not outweigh risk
Precautions
For use only when prompt catharsis is desired
Casanthranol
Anthraquinone stimulant that is hydrolyzed by colonic bacteria into its active compound. Usually produces action 8-12 h after administration.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
0.12-0.25 g/d PO
Pediatric
<6 years: Not recommended
>6 years: Administer as in adults
* Dosing
* Interactions
* Contraindications
* Precautions
Decreases the effect of anticoagulants
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; nausea, vomiting; GI bleeding; appendicitis; congestive heart failure; fecal impaction
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Excessive use may lead to electrolyte imbalance, osteomalacia, steatorrhea, cathartic colon
Prokinetics
Promotility agents proposed for use with severe constipation-predominant symptoms.15
Tegaserod marketing was temporarily withdrawn from the US market in March 2007; however, as of July 27, 2007, restricted use of tegaserod is now permitted via a treatment investigational new drug (IND) protocol.16 The treatment IND protocol will allow tegaserod treatment of irritable bowel syndrome with constipation (IBS-C) or chronic idiopathic constipation (CIC) in women younger than 55 years who meet specific guidelines. Its use is further restricted to those in critical need who have no known or preexisting heart disease.
Earlier in 2007, tegaserod marketing was suspended because of a meta-analysis of safety data pooled from 29 clinical trials that involved more than 18,000 patients. The results showed an excess number of serious cardiovascular adverse events, including angina, myocardial infarction, and stroke, in those taking tegaserod compared with placebo. In each study, patients were assigned at random to either tegaserod or placebo. Tegaserod was taken by 11,614 patients, and placebo was taken by 7,031 patients. The average age of patients in these studies was 43 years, and most patients (ie, 88%) were women. Serious and life-threatening cardiovascular adverse effects occurred in 13 patients (0.1%) treated with tegaserod; among these, 4 patients had a heart attack (1 died), 6 had unstable angina, and 3 had a stroke. Among the patients taking placebo, only 1 (0.01%) had symptoms suggesting the beginning of a stroke that went away without complication.
For more information, see the FDA MedWatch Product Safety Alert.
Tegaserod (Zelnorm)
Available in US by restricted treatment IND for irritable bowel syndrome with constipation (IBS-C) or chronic idiopathic constipation (CIC) in women younger than 55 years who meet specific guidelines. Indicated to treat chronic idiopathic constipation. Also indicated for the short-term treatment of women with IBS in whom constipation is the predominant symptom. Serotonin type 4 receptor partial agonist with no affinity for 5-HT3 receptors. May trigger peristaltic reflex via 5-HT4 activation, which enhances basal motor activity and normalizes impaired GI motility. Research studies have shown inhibitory activity of the drug on visceral activity in the GI tract.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
Chronic idiopathic constipation: 6 mg PO bid before meals; periodically assess to determine needed for need for continued use
Pediatric
Not established
* Dosing
* Interactions
* Contraindications
* Precautions
None reported
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; severe renal impairment; moderate or severe renal impairment; history of bowel obstruction, symptomatic gallbladder disease, suspected sphincter of Oddi dysfunction, or abdominal adhesions
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Diarrhea may occur; do not administer to patients with diarrhea; discontinue if new or sudden worsening of abdominal pain or diarrhea occurs
Opioid antagonist
Peripherally selective opioid antagonists are now available. Methylnaltrexone is indicated to treat constipation in patients who have advanced illness requiring chronic opioid analgesia and are unresponsive to laxatives. Alvimopan is indicated to prevent postoperative ileus following bowel resection.
Methylnaltrexone (Relistor)
Peripherally acting mu-opioid receptor antagonist. Selectively displaces opioids from mu-opioid receptors outside CNS, including those located in GI tract, thereby decreasing constipating effects. Indicated for opioid-induced constipation in patients with advanced illness receiving palliative care, when response to laxatives has not been sufficient. Available as a 12-mg/0.6 mL injectable solution for subcutaneous use.
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
Usually administered as 1 dose qod prn; not to exceed 1 dose/24 h
<38 kg: 0.15 mg/kg SC (round dose to nearest 0.1 mL)
38-61 kg: 8 mg (0.4 mL) SC
62-113 kg: 12 mg (0.6 mL) SC
>114 kg: 0.15 mg/kg SC (round dose to nearest 0.1 mL)
CrCl <30 mL/min: Reduce dose by 50%
Pediatric
Not established
* Dosing
* Interactions
* Contraindications
* Precautions
Data limited; none reported
* Dosing
* Interactions
* Contraindications
* Precautions
Documented hypersensitivity; known or suspected mechanical GI obstruction
* Dosing
* Interactions
* Contraindications
* Precautions
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Common adverse effects include abdominal pain, flatulence, nausea, dizziness, and diarrhea; discontinue use and contact clinician if severe or persistent diarrhea occurs
Alvimopan (Entereg)
Peripherally acting mu-opioid receptor antagonist. Binds mu-opioid receptors in gut, thereby selectively inhibiting negative opioid effects on GI function and motility. Indicated for postoperative ileus following bowel resection with primary anastomosis. Five clinical studies with enrollment >2500 patients demonstrated accelerated recovery time of upper and lower tract GI function with alvimopan compared with placebo. Decrease of hospital days also observed in alvimopan group compared with placebo.
Only available to hospitals after they complete a registration process designed to maintain the benefits associated with short-term use and prevent long-term, outpatient use (Entereg Access Support and Education [EASE] program).
* Dosing
* Interactions
* Contraindications
* Precautions
Adult
12 mg PO as single dose 0.5-5 h preoperatively, followed by 12 mg PO bid starting the day after surgery; not to exceed treatment duration of 7 days (or 15 doses)
Pediatric
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Follow-up
Further Inpatient Care
* Once acute constipation has resolved and the associated medical or surgical conditions have been ruled out, additional inpatient care is rarely indicated.
* Patients requiring surgical intervention for acute conditions, such as large bowel obstruction, volvulus, toxic megacolon, and, rarely, chronically atonic colon that requires colectomy, need postoperative care, but that is beyond the scope of this article.
Further Outpatient Care
* After constipation resolves, outpatient care for the acutely constipated patient requires the following measures:
o To ascertain that the patient is not chronically constipated
o To rule out colorectal pathology
* For the patient who is chronically constipated, outpatient care may include the following:
o Colonic imaging or endoscopic visualization
o Dietary management
o If these measures fail in a compliant patient, further evaluation is indicated.
Transfer
* Generally, transfer is not required unless uncertainty exists concerning the diagnosis or the underlying cause and more aggressive medical evaluation is necessary. Such an eventuality might occur in patients institutionalized in nursing homes or in chronic care facilities who require medical consultations to rule out conditions that are more serious. The following factors may warrant a transfer:
o Uncertain diagnosis
o Evidence of intra-abdominal catastrophe
o Acute abdominal pain
o Fever
o Lower GI bleeding
o Chills
o Instability of vital signs
o Absence of bowel sounds
o Acute recent change in bowel habits
o Unsuccessful or inadequate treatment offered at the local facility
Deterrence/Prevention
* In children and in mentally incapacitated patients with a pattern of bowel retention, resolution of this pattern requires aggressive short-term use of laxatives, stool softeners, and local care of any anal fissures. Once this pattern has been unlearned, usually within several weeks, laxatives should be gradually tapered off while the use of fiber and fluid supplementation should indefinitely continue.
* Failure to taper the laxatives without the return of constipation indicates the need for a gastroenterologic consultation to rule out an underlying problem.
Complications
* Generally, hemorrhoids are medically managed. Surgical intervention is reserved for when medical management fails.
* Generally, fissures are medically managed. Surgical intervention is reserved for when medical management fails.
* Fistulae-in-ano require surgical therapy.
* The chronic pressure effect of hard stools against the anterior rectal wall when the patient strains during defecation is believed to cause solitary rectal ulcers. This is usually a self-limiting process and responds to treatment for constipation. In adults, surgical or gastroenterologic consultation may be required to differentiate benign solitary rectal ulcers from rectal malignancy.
* Melanosis coli from prolonged laxative use is an incidental finding at endoscopy.
Prognosis
* With appropriate dietary management, prognosis in most patients is excellent. Recurrence depends on the patient's long-term compliance to therapy.
* 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.
o Most patients can be treated with a combination of fiber, water, and osmotic agents, such as sorbitol. However, the need for increasing doses of laxatives and the intermittent use of other agents becomes problematic.
o 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
* The prognosis is excellent for patients who implement dietary changes.
* Dietary deficiency requires increased fluid and fiber supplementation for life.
* For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education articles Constipation in Adults and Constipation in Children.
Miscellaneous
Medicolegal Pitfalls
* Failure to identify colorectal cancer
* Overlooking an anal fissure in a constipated child
* Misdiagnosing colonic ileus secondary to sepsis or an intra-abdominal catastrophe as constipation
* Misdiagnosing large bowel obstruction as constipation
* Surgical intervention for constipation in a patient with an underlying psychiatric cause
Special Concerns
* Pregnant women are frequently constipated because of dietary alterations, anatomical impingement of a large uterus on the rectosigmoid, fluid shifts, and decreased exercise and mobility. Typically, these women develop hemorrhoids from passive venous congestion and uterine impingement. Pregnancy-related constipation potentiates the development of symptomatic hemorrhoids, and the resolution of constipation is the only available antihemorrhoidal therapy during pregnancy.
o First-line treatment is fiber supplementation, increased water intake, gentle exercise, and occasional laxative use as required.
o Hemorrhoidal suppositories and sitz baths may offer symptomatic relief.
o Attentive management is particularly important to minimize acute and subacute hemorrhoidal complications induced by the straining associated with vaginal delivery.
* Elderly patients appear particularly prone to constipation. The rate of self-reported constipation rapidly increases in patients older than 65 years.
o Careful review of prescribed medications may reveal 1 or more that may potentiate constipation.
o Manipulating their diets and encouraging patients to exercise are the cornerstones of treatment.
o Laxatives may be required, particularly in patients with a history of chronic laxative abuse.
* Constipation in children is frequently diet-related, particularly toddlers who are being switched from formula feeds to milk. Small children are especially liable to develop constipation that is more prolonged. This is associated with painful bowel movements caused by an acute anal fissure, which forces the child to avoid bowel movements.
o Painful defecation produces a vicious positive feedback cycle. The child suppresses the urge to defecate, resulting in a larger and harder stool. When the stools eventually emerge, the pain of defecation is worse, encouraging the child to retain the stools further.
o Prescribing long-term laxatives for a period of several weeks may be necessary in order to force the child to defecate daily until the cause of the anorectal pain is resolved and the fecal retention behavior is unlearned.
o The first-line therapy remains dietary manipulation, with increased fluid intake and the use of dietary fiber via fruits and vegetables or supplementation with more purified forms of fiber, such as wheat germ, psyllium, methylcellulose, or agents like Maltsupex. These may be mixed with liquids and administered with the help of a child's feeding bottle.
