Constipation | Chronic Constipation | Constipation Relief | Constipation Symptoms And Treatment


Constipation
Constipation most often occurs in patients at the ex treme ages of life. Most individuals eating an average diet will pass at least three stools per week, making it useful to define constipation clinically as the passage of less than three stools per week. Other criteria that can be used to define constipation include lumpy or hard stools, straining, a sensation of incomplete evac uation, and the need to use manual maneuvers such as digital extraction to facilitate defecation. PATHOGENESIS OF CONSTIPATION The passage of stool depends on stool volume, colonic motility, and patency of the colon's lumen. Defecation requires a complex interaction between the central nervous system and the muscles that increase intra abdominal pressure, relax the sphincter, and open the canal. Alteration of any one of these components can cause constipation. Anorectal disorders such as anal fis sures or thrombosed hemorrhoids that cause pain can also lead to constipation by causing avoidance of defe cation. Mechanical obstruction as seen in cancer, strictures, or external compression is another cause of constipation. Patients with diminished fluid and fiber intake have decreased stool volume and can experience constipation. Colonic motility can be inhibited by a variety of medical conditions including hypothyroidism, hypercalcemia, hypokalemia, sderoderma, diabetes, and neurologic dis orders such as multiple sclerosis, Parkinson disease, and paraplegia. Medications such as calcium channel block ers (e.g., verapamil), narcotics, and anticholinergics commonly cause a delay in colonic motility. Irritable bowel syndrome (IBS) is characterized by abnormal colonic motility, with delayed colonic transit followed by periods of more frequent and looser stools. A sedentary lifestyle or bed rest (e.g., postoperative patients) results in significant slowing of fecal matter through the colon. Congenital disorders such as Hirschsprung disease may also lead to delayed emptying. CLINICAL MANIFESTATIONS OF CONSTIPATION HISTORY Since many patients have misconceptions regard ing normal stool patterns, the frequency of bowel movements and consistency of stool must be accu rately determined. It is important to inquire about symptoms such as pain with defecation, abdominal distention, gas, nausea, emesis, abdominal discomfort, and the presence of blood in the stool. A dietary his tory should include questions about the type and quantities of liquid, fruits, vegetables, and fiber as well as any recent change in diet. Past medical history, previous surgeries, exercise frequency, and family history should be elicited. A re view of medications, including over-the-counter medications, may identify the underlying cause. The review of systems should include questions about weight loss, fatigue, depression, and anxiety. PHYSICAL EXAMINATION OF CONSTIPATION The physical examination begins with a general assess ment of nutritional status, weight, and vital signs. The thyroid gland should be examined for abnormalities and the skin assessed for pallor or signs of scleroderma. The abdominal examination should note the fre quency and pitch of bowel sounds, the presence of any distention or masses, and focal tenderness. Rectal ex amination is useful for determining stool consistency, detecting occult blood, and ruling out rectal abnormal ities such as fissure, ulcers, masses, or hemorrhoids as well as detecting impaction. A neurologic examination may detect signs of dementia, Parkinson disease, or neuropathy. DIFFERENTIAL DIAGNOSIS Causes can be related to colonic disease, structural ab normalities, anorectal disease, extracolonic disease, medications, diet, and psychological factors. In the out patient setting, dietary factors (particularly inadequate fiber), medications, IBS, and poor fluid intake are com mon causes of constipation. DIAGNOSTIC EVALUATION OF CONSTIPATION The history and physical examination determine the need for further testing. In younger persons with a rea sonable explanation for constipation, management can be instituted without further evaluation. Further testing Causes of Constipation Insufficient dietary fiber Inactivity Medications Opiates Calcium channel blockers Anticholinergics Tricyclic antidepressants Diuretics Antacids Clonidine Levodopa Laxative abuse Metabolic Abnormalities Hypokalemia Hypercalcemia Hypothyroidism Scleroderma Amyloidosis Pregnancy Neurologic Disorders Parkinson disease Paraplegia Prior pelvic surgery Diabetes mellitus Irritable bowel syndrome Colonic mass Hirschsprung disease Perianal Pathology Fissure Hemorrhoids Rectocele Rectal prolapse Diverticular disease is indicated in cases refractory to treatment, in older adults with new-onset constipation, in cases where the etiology is uncertain, or if the clinical evaluation sug gests an underlying disorder that merits further evalua tion. Laboratory evaluation should include a CBC, serum electrolytes, TSH, and calcium level. Anoscopy is helpful if there is concern about anal pathology such as internal hemorrhoids and fissures. Abdominal x-rays are of limited value unless ob struction or fecal impaction is suspected. Further evaluation using flexible sigmoidoscopy, coupled with a barium enema or colonoscopy, may be necessary to detect strictures, masses, polyps, or diverticular disease. A full colonoscopy is indicated in patients with anemia, weight loss, heme-positive stools, or other situations in which a malignancy is suspected. During colonoscopy, biopsies of the mucosa can be performed to rule out amyloidosis, Hirschsprung disease, and cancer. The ab sence of neurons on a rectal biopsy demonstrates the presence of Hirschsprung disease. TREATMENT FOR CONSTIPATION Disorders causing constipation such as hypothyroidism, bowel obstruction, or anal fissure should be treated ac cordingly. Some patients may only require education and reassurance that their bowel pattern is normal. Increasing fluid and fiber is the cornerstone for treat ing cases of functional constipation. Patients should drink at least eight 8-oz glasses of water and consume large amounts of bran, fresh fruit, vegetables, beans, and whole grains. For those with limited fiber intact, dietary fiber should be increased gradually over a 2- to 3-week period in order to minimize adverse effects with a target of consuming 20 to 25 g daily. If possible, med ications suspected to be causing or contributing to constipation should be discontinued or changed. Patients may also benefit from `bowel retraining." Specifically, patients should spend 10 to 15 quiet and un hurried minutes each day on the commode. This should take place at the same time each day and occur after a meal so as to utilize the gastro-colic reflex. Bowel retrain ing often requires 2 to 3 weeks to become effective and should become a part of the patient's daily routine. If these modalities fail to alleviate the patient's symptoms and bowel obstruction has been ruled out, medications may be required. Numerous medications are available to treat constipation and some have signif icant side effects. However, with adequate knowledge of the mechanism of action and risks, most medications for constipation can be administered safely. BULK-FORMING AGENTS Bulk-forming agents are high in fiber and increase stool volume by absorbing water. Examples include psyllium (Metamucil), methylcellulose (Citrucel), and polycarbophil (FiberCon). Common side effects include bloating and flatulence; if these agents are not taken with enough water, they may paradoxically worsen constipation. OSMOTIC LAXATIVES Osmotic laxatives are nonabsorbable solutes that draw fluid into the intestinal lumen by creating an osmotic gradient. Examples include lactulose, magnesium salts (Milk of Magnesia) and sorbitol. Side effects include bloating, excess gas, and abdominal cramping. Magnesium salts are contraindicated in patients with renal failure. STIMULANT AGENTS Stimulants work by altering mucosal permeability and stimulating the activity of intestinal smooth mus cle. Examples include phenolphthalein (Ex-Lax) and bisacodyl (Dulcolax). Chronic abuse of these may lead to melanosis coli and constipation secondary to enteric nervous system damage. STOOL SOFTENERS Docusate sodium (Colace), a commonly prescribed stool softener, is often used for patients complaining of hard stools that are difficult to pass. It decreases surface tension and allows water and fat to mix in the stool. To work optimally, stool softeners must be taken with plenty of fluid. ENEMAS AND SUPPOSITORIES Warm tap-water enemas and suppositories work by dis tending and stimulating the rectum, which then leads to evacuation. These measures are especially useful in bedridden patients and those with stool impaction. In patients with severe idiopathic constipation, surgeries such as hemicolectomy with ileorectal anastomosis may be a last resort. KEY POINTS IN CONSTIPATION Constipation is defined clinically as less than three stools per week. Poor fluid intake and a lack of fiber are com mon causes of constipation in the primary care setting. Indications for laboratory testing include re fractory constipation, a new onset of constipa tion in an older individual, heme-positive stools, and situations in which the etiology is unclear or the clinical evaluation suggests un derlying pathology. The types of laxatives include bulk-forming agents, osmotic laxatives, stimulant laxatives, stool softeners, suppositories, and enemas.