Constipation
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International Foundation for Functional Gastrointestinal Disorders IFFGD Phone: 414-964-1799 700 W. Virginia St., #201 Toll-Free(In the U.S.): 888-964-2001 Milwaukee, WI 53204 Fax: 414-964-7176 Internet: www.iffgd.org Constipation (118) © Copyright 1994-2013 by the International Foundation for Functional Gastrointestinal Disorders Revised by IFFGD, 2013 Evaluation and Treatment of Constipation By: M. Scott Harris, M.D., Georgetown University School of Medicine, and Middleburg Consultants, Washington, D.C. Constipation is one of the most common gastrointestinal Dietary fiber retains water in the stool and is responsible complaints in the United States. It afflicts approximately 1 for stools that are bulkier, softer, and easier to pass. A in 6 individuals and is responsible for approximately 2.5 change from liquid to semisolid occurs in the right and million physician visits each year. More than $400 million transverse portions of the colon (Figure 1). Although is spent annually on over-the-counter laxatives; at least undigested food takes less than two hours to reach the 120 of these products are available. Although constipation colon, it may take as long as 2 to 5 days for it to be affects all ages, both males and females, and all expelled as stool. This prolonged transit time is an educational and socioeconomic levels, it is more common important aspect of colonic function as it permits a longer in the elderly. Women are affected two to three times period of time for water reabsorption to occur. more often than men. Constipation also accounts for over The descending colon serves as conduit through which 13 million days of restricted activity and 3 million days of stool is transferred to the rectosigmoid. The rectosigmoid serves as a storage area where stool water is further bed disability each year. Economic impact on resource recovered through absorption. Contraction and emptying utilization, quality of life and productivity is considerable. of the descending colon and rectosigmoid is stimulated by Although constipation is a common problem, it is one eating (gastrocolic reflex). In the rectum, the pelvic floor that is poorly understood. Constipation represents an muscles (levator ani, puborectalis) regulate fecal retention abnormality of bowel function. The term “abnormality” and defecation (Figure 2). The puborectalis suspends the implies a deviation from normal, but there is no agreement rectosigmoid and imposes constraints which facilitate as to what constitutes normal bowel habits. Physicians voluntary stool retention (continence). Continence is also know what constipation is but have trouble accurately promoted by contraction of the internal and external anal defining it. Patients may complain of bowel movements sphincters. that are too infrequent or stools that are too hard, or they The urge to defecate is signaled by the propulsion of may be referring to defecation that feels incomplete. feces from the sigmoid colon to rectum. Distention These symptoms may or may not imply specific of the rectum causes relaxation of the internal anal abnormalities in bowel function. Since stool frequency is sphincter. For defecation to proceed, the external anal the easiest factor to measure, it is often used as a sphincter and puborectalis must be voluntarily relaxed. definition. Great variation in bowel frequency exists in the With straining, the pelvic floor muscles descend, general population. The typical Westerner may have permitting straightening of the anus and rectum. anywhere from two bowel movements per day to two Defecation is facilitated by squatting or sitting and by bowel movements per week. increasing intra-abdominal pressure. Normal colonic function – Evaluation of the patient The process of defecation is learned early in with constipation requires understanding of normal childhood and retains spontaneity throughout life in most function of the colon and anorectal area. The colon is a persons. The spontaneity of this process may be lost due muscular organ, which is supplied by nerves originating to trauma that occurs from childbirth or other reasons. both within and external to the surface that can absorb When puborectalis or external anal sphincter more than 90% of the fluid which enters it. In normal relaxation is incomplete, functional obstruction (anismus) individuals, approximately 3 to 4 pints of fluid, may occur. Derangements (irregularities) in muscular representing bile, digestive juices, and ingested food, enter relaxation may be congenital (Hirschsprung’s disease). the colon from the small intestine each day. The colon is Congenital diseases are most often diagnosed in childhood able to reabsorb the majority of this fluid, reducing the but numerous cases of Hirschsprung’s disease have been water content of the stool to about one-tenth this amount. reported in adulthood. Nerves and muscles regulate the transit Sigmoid time of the colon. Derangements in either element may seriously disturb colonic Transverse colon Rectum function. When colonic transit time is prolonged (colonic inertia), excess fecal Descending water reabsorption and retention may occur. Right colon A number of diseases, such as diabetes or colon scleroderma can affect the neural elements Pubo- rectalis of the colon, resulting in severe constipation. muscle Chronic stimulant laxative use can also result in damage to neural elements of the Internal anal Rectum sphincter colon. The malady feeds itself, because Rectosigmoid individuals, with time, become increasingly Anal canal External anal sphincter dependent on laxatives which may be damaging the intrinsic neural function of the FIGURE 1 FIGURE 2 colon. Assessment – A variety of diseases and conditions cause or are associated with constipation (Table 1). Medications should Conditions Associated with Constipation always be considered as a cause of constipation (Table 2). Inactivity, especially Colonic Disorders Hormonal in bed-bound patients, may result in Irritable bowel syndrome Pregnancy constipation. Depressed patients are more Diabetes Cancer likely to become constipated but many of Abnormalities of thyroid or parathyroid Inflammation aafunction the drugs used to treat depression are Diverticulitis themselves constipating. In many patients, Crohn’s disease Neurological no immediate cause for constipation will be Chronic laxative use (cathartic colon) Multiple sclerosis identified. Stroke Pelvic muscle injury Spinal cord injury Evaluation should begin with a history Rectal prolapse and physical examination. Patients should be Rectocele asked what they mean by constipation and Anal disease Anal stricture what their “normal” bowel habit is. The Incomplete anal relaxation duration of symptoms, frequency of bowel Hirschsprung’s disease (hereditary) movements, consistency of stools, straining Anismus (acquired) or pain, sense of incomplete evacuation, and TABLE 1 presence of blood should be documented. Colon cancer should be suspected in any patient over 40 with a change in bowel habit of short duration, gross bleeding, or a family history of colon cancer. Medications should Medications That May Cause Constipation be reviewed, including the use of over-the- counter laxatives, and dietary fiber intake Antacids that contain aluminum or Medications to treat high blood calcium pressure should be quantitated by a careful diet history. Rectal examination should be Iron supplements Calcium channel antagonists (e.g. Linosopril, Vasotec, Capoten) performed by the physician to evaluate anal Opiate-type pain medications (e.g. sphincter tone and voluntary puborectalis Percocet, Percodan, Lortabs, Darvocet) Clonidine relaxation and detect signs of tenderness, Antidepressants Diuretics (“water pills”) that cause obstructing masses, or blood. Screening potassium loss Antiparkinson drugs blood studies often point to underlying Nasal decongestants and conditions such as diabetes or a hypoactive antihistamines thyroid gland. TABLE 2 If underlying pathology (abnormality) is suspected, structural evaluation of the colon by colonoscopy is recommended. In selected patients, include products containing psyllium seed husk specialized studies may be employed. The speed at which (Metamucil, Konsyl), or methylcellulose (Citrucel), or food moves through the colon can be evaluated by polycarbophyl (Fibercon). Bulk-forming agents are viewing radiopaque markers (Sitz markers) on abdominal available in a variety of forms (e.g., granular, powder, x-ray five days after ingestion. Anorectal manometry can cookie, or tablet). The dose should be increased gradually be used to measure resting and squeezing anal sphincter since patients may initially experience abdominal pressures, rectal sensation, compliance, and sphincter cramping, bloating, and flatulence as a result of gas response. Hirschsprung’s disease may present in production by colonic bacteria. adulthood and it is important to consider this possibility in Laxatives act by stimulating colonic water and individuals with constipation dating back to birth. electrolyte secretion. So-called surface-acting agents or Defecography evaluates completeness of rectal expulsion, stool softeners, which include docusate salts (Colace, identifies anatomic abnormalities, and evaluates Surfak), are surfactant fatty acids that may also provide puborectalis muscle relaxation by radiographic techniques. some lubricating function. They are poorly named since Management – The management of constipation they primarily work by stimulating colonic secretion and includes patient education about