Constipation - Abnormalities of Fecal Elimination

Abnormalities of Fecal Elimination

Changes in patterns of fecal elimination are symptoms of func-tional disorders or disease of the GI tract. The most common changes seen are constipation, diarrhea, and fecal incontinence. The nurse should be aware of the possible causes and thera-peutic management of these problems and of nursing manage-ment techniques. Education is important for patients with these abnormalities.

CONSTIPATION

Constipation is a term used to describe an abnormal infrequencyor irregularity of defecation, abnormal hardening of stools that makes their passage difficult and sometimes painful, a decrease in stool volume, or retention of stool in the rectum for a prolonged period. Any variation from normal habits may be considered a problem.

Constipation can be caused by certain medications (ie, tran-quilizers, anticholinergics, antidepressants, antihypertensives, opioids, antacids with aluminum, and iron); rectal or anal disor-ders (eg, hemorrhoids, fissures); obstruction (eg, cancer of the bowel); metabolic, neurologic, and neuromuscular conditions (eg, diabetes mellitus, Hirschsprung’s disease, Parkinson’s dis-ease, multiple sclerosis); endocrine disorders (eg, hypothy-roidism, pheochromocytoma); lead poisoning; and connective tissue disorders (eg, scleroderma, lupus erythematosus). Consti-pation is a major problem for patients taking opioids for chronic pain. Diseases of the colon commonly associated with constipation are irritable bowel syndrome (IBS) and diverticular disease. Constipation can also occur with an acute disease process in the abdomen (eg, appendicitis).

Other causes include weakness, immobility, debility, fatigue, and an inability to increase intra-abdominal pressure to facilitate the passage of stools, as occurs with emphysema. Many people de-velop constipation because they do not take the time to defecate or they ignore the urge to defecate. In the United States, consti-pation is also a result of dietary habits (ie, low consumption of fiber and inadequate fluid intake), lack of regular exercise, and a stress-filled life.

Perceived constipation can also be a problem. This subjective problem occurs when an individual’s bowel elimination pattern is not consistent with what he or she perceives as normal. Chronic laxative use is attributed to this problem and is a major health concern in the United States, especially among the elderly population.

Pathophysiology

The pathophysiology of constipation is poorly understood, but it is thought to include interference with one of three major func-tions of the colon: mucosal transport (ie, mucosal secretions fa-cilitate the movement of colon contents), myoelectric activity (ie, mixing of the rectal mass and propulsive actions), or the processes of defecation. Any of the causative factors previously identified can interfere with any of these three processes.

The urge to defecate is stimulated normally by rectal disten-tion, which initiates a series of four actions: stimulation of the in-hibitory rectoanal reflex, relaxation of the internal sphincter muscle, relaxation of the external sphincter muscle and muscles in the pelvic region, and increased intra-abdominal pressure. Interference with any of these processes can lead to constipation.If all organic causes are eliminated, idiopathic constipation is diagnosed.

If the urge to defecate is ignored, the rectal mucous membrane and musculature become insensitive to the presence of fecal masses, and consequently, a stronger stimulus is required to produce the necessary peristaltic rush for defecation. The ini-tial effect of fecal retention is to produce irritability of the colon, which at this stage frequently goes into spasm, especially after meals, giving rise to colicky midabdominal or low abdominal pains. After several years of this process, the colon loses muscular tone and becomes essentially unresponsive to normal stimuli. Atony or decreased muscle tone occurs with aging. This also leads to constipation because the stool is retained for longer periods.

Clinical Manifestations

Clinical manifestations include abdominal distention, borborygmus (ie, gurgling or rumbling sound caused by passage of gas through the intestine), pain and pressure, decreased appetite, headache, fa-tigue, indigestion, a sensation of incomplete emptying, straining at stool, and the elimination of small-volume, hard, dry stools.

Assessment and Diagnostic Findings

Chronic constipation is usually considered idiopathic, but sec-ondary causes should be excluded. In patients with severe, in-tractable constipation, further diagnostic testing is needed (Wong, 1999). The diagnosis of constipation is based on results of the pa-tient’s history, physical examination, possibly a barium enema or sigmoidoscopy, and stool testing for occult blood. These tests are completed to determine whether this symptom results from spasm or narrowing of the bowel. Anorectal manometry (ie, pressure studies) may be performed to determine malfunction of the mus-cle and sphincter. Defecography and bowel transit studies can also assist in the diagnosis.

Complications

Complications of constipation include hypertension, fecal im-paction, hemorrhoids and fissures, and megacolon. Increased arte-rial pressure can occur with defecation. Straining at stool, which results in the Valsalva maneuver (ie, forcibly exhaling with the glot-tis closed), has a striking effect on arterial blood pressure. During active straining, the flow of venous blood in the chest is temporar-ily impeded because of increased intrathoracic pressure. This pres-sure tends to collapse the large veins in the chest. The atria and the ventricles receive less blood, and consequently less is delivered by the systolic contractions of the left ventricle. The cardiac output is decreased, and there is a transient drop in arterial pressure. Almost immediately after this period of hypotension, a rise in arterial pres-sure occurs; the pressure is elevated momentarily to a point far ex-ceeding the original level (ie, rebound phenomenon). In patients with hypertension, this compensatory reaction may be exaggerated greatly, and the peaks of pressure attained may be dangerously high—sufficient to rupture a major artery in the brain or elsewhere.

Fecal impaction occurs when an accumulated mass of dry feces cannot be expelled. The mass may be palpable on digital examina-tion, may produce pressure on the colonic mucosa that results in ulcer formation, and frequently may cause seepage of liquid stools.

Hemorrhoids and anal fissures can develop as a result of con-stipation. Hemorrhoids develop as a result of perianal vascular congestion caused by straining. Anal fissures may result from the passage of the hard stool through the anus, tearing the lining of the anal canal.

Megacolon is a dilated and atonic colon caused by a fecal mass that obstructs the passage of colon contents. Symptoms include constipation, liquid fecal incontinence, and abdominal disten-tion. Megacolon can lead to perforation of the bowel.

Gerontologic Considerations

Physician visits for constipation are more frequent by individuals 65 years of age or older (Yamada et al., 1999). Elderly people re-port problems with constipation five times more frequently than younger people. A number of factors contribute to this increased frequency. People who have loose-fitting dentures or have lost their teeth have difficulty chewing and frequently choose soft, processed foods that are low in fiber. Convenience foods, also low in fiber, are widely used by those who have lost interest in eating. Some older people reduce their fluid intake if they are not eating regular meals. Lack of exercise and prolonged bed rest also con-tribute to constipation by decreasing abdominal muscle tone and intestinal motility as well as anal sphincter tone. Nerve impulses are dulled, and there is decreased sensation to defecate. Many older people who overuse laxatives in an attempt to have a daily bowel movement become dependent on them.

Medical Management

Treatment is aimed at the underlying cause of constipation and includes education, bowel habit training, increased fiber and fluid intake, and judicious use of laxatives. Management may also in-clude discontinuing laxative abuse. Routine exercise to strengthen abdominal muscles is encouraged. Biofeedback is a technique that can be used to help patients learn to relax the sphincter mecha-nism to expel stool. Daily addition to the diet of 6 to 12 tea-spoonfuls of unprocessed bran is recommended, especially for the treatment of constipation in the elderly. If laxative use is necessary, one of the following may be prescribed: bulk-forming agents, saline and osmotic agents, lubricants, stimulants, or fecal soften-ers. The physiologic action and patient education information re-lated to these laxatives are identified in Table 38-1. Enemas and rectal suppositories are generally not recommended for constipa-tion and should be reserved for the treatment of impaction or for preparing the bowel for surgery or diagnostic procedures. If long-term laxative use is necessary, a bulk-forming agent may be pre-scribed in combination with an osmotic laxative.

Doctors prescribe the use of specific medications to enhance colonic transit by increasing propulsive motor activity. Further studies are being carried out on cholinergic agents (eg, bethane-chol), cholinesterase inhibitors (eg, neostigmine), and prokinetic agents (eg, metoclopramide) to determine the role these agents can play in treating constipation (Yamada et al., 1999).

Nursing Management

The nurse elicits information about the onset and duration of con-stipation, current and past elimination patterns, the patient’s ex-pectation of normal bowel elimination, and lifestyle information (eg, exercise and activity level, occupation, food and fluid intake, and stress level) during the health history interview. Past medical and surgical history, current medications, and laxative and enema use are important, as is information about the sensation of rectal pressure or fullness, abdominal pain, excessive straining at defeca-tion, and flatulence.

Patient education and health promotion are important functions of the nurse (Chart 38-1). After the health history is obtained, the nurse sets specific goals for teaching. Goals for the patient include restoring or maintaining a regular pattern of elimination, ensur-ing adequate intake of fluids and high-fiber foods, learning about methods to avoid constipation, relieving anxiety about bowel elimination patterns, and avoiding complications.