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Constipation is the slow movement of feces through the large intestine that results in the passage of dry, hard stool. This can result in discomfort or pain. The longer the transit time of stool in the large intestine, the greater the fluid absorption and the drier and harder the stool becomes.
Constipation may be annoying and uncomfortable, but fecal impaction can be life-threatening. Impaction refers to the accumulation of dry, hardened feces in the rectum or colon. The patient with fecal impaction may present with circulatory, cardiac, or respiratory symptoms rather than with gastrointestinal symptoms. If the fecal impaction is not recognized, the signs and symptoms may progress and result in death.
In contrast to constipation or impaction, an intestinal obstruction is a partial or complete occlusion of the bowel lumen by a process other than fecal impaction. Intestinal obstructions can be classified by three means: the type of obstruction, the obstructing mechanism, and the part of the bowel involved.
Structural disorders, such as intraluminal and extraluminal bowel lesions caused by primary or metastatic tumor, postoperative adhesions, volvulus of the bowel, or incarcerated hernia, affect peristalsis and the maintenance of normal bowel function. These disorders can lead to total or partial obstruction of the bowel. Patients who have colostomies are at special risk of developing constipation. If stool is not passed on a regular basis (generally, once a day to several times a day), further investigation is warranted. A partial or complete blockage may have occurred, particularly if no flatus has been passed.
Functional disorders such as inactivity, immobility, or physical and social impediments (particularly inconvenient bathroom availability) can contribute to constipation. Depression and anxiety caused by cancer treatment or cancer pain can lead to constipation, either alone or with other functional and physiologic disorders. Perhaps the most common causes are inadequate fluid intake and pain medications. These are manageable. It should be noted that management of the pediatric patient varies from the adult patient and should be adjusted accordingly.
Constipation is frequently the result of autonomic neuropathy caused by the vinca alkaloids, taxanes, and thalidomide. Other drugs such as opioid analgesics or anticholinergics (antidepressants and antihistamines) may lead to constipation by causing decreased sensitivity to the defecation reflexes, and decreased gut motility. Since constipation is common with the use of opioids, a bowel regimen should be initiated at the time opioids are prescribed and continued for as long as the patient takes opioids. Opioids produce varying degrees of constipation, suggesting a dose-related phenomenon.
Other diseases such as diabetes (with autonomic neuropathy) and hypothyroidism may cause constipation. Metabolic disorders such as hypokalemia and hypercalcemia also predispose cancer patients to developing constipation. Once these disorders are corrected, constipation should subside.
The following questions may provide a useful assessment guide:
1. What is normal for the patient: frequency, amount, and timing?
2. When was the last bowel movement? What was the amount, consistency, and
color? Was blood passed with it?
3. Has the patient been having any abdominal discomfort, cramping, nausea or
vomiting, pain, excessive gas, or rectal fullness?
4. Does the patient regularly use laxatives or enemas? What does the patient
usually do to relieve constipation? Does it usually work?
5. What type of diet does the patient follow? How much and what type of fluids
are taken on a regular basis?
6. What medication (dose and frequency) is the patient taking?
7. Is this symptom a recent change?
8. How many times a day is flatus passed?
Physical assessment will determine the presence or absence of bowel sounds, flatus, or abdominal distention. Patients with colostomies should also be assessed for constipation. Dietary habits, fluid intake, activity levels, and use of opioids in these patients should be assessed. Irrigation of the colostomy should be monitored for proper technique.
Goal: Prevention of constipation with evacuation of at least one soft stool daily.
1. Establish the patient's normal bowel pattern and habits (time of day for
normal bowel movement, consistency, color, and amount).
2. Explore the patient's level of understanding and compliance relating to
exercise level, mobility, and diet (fluid, fruit, and fiber intake).
3. Determine normal or usual use of laxatives, stimulants, or enemas.
4. Determine laboratory values, specifically looking at platelet count.
5. Conduct a physical assessment of the rectum (or stoma) to rule out
Commonly used interventions include (record bowel movements daily):
stool softeners (e.g., docusate sodium, 1-2 capsules per day). For
opioid-related constipation, stool softeners should be used in combination
with a stimulant laxative. Bulk producing agents are not recommended for
use in a regimen used to counteract the bowel effects of opioids.
2 tablets of a senna preparation twice daily.
5 mL of cascara at bedtime.
1 bisacodyl tablet at bedtime.
milk of magnesia, 30 to 45 mL if a bowel movement is not achieved in 24
hours after other methods are instituted.
Rectal agents should be avoided in cancer patients at risk for thrombocytopenia, leukopenia, and/or mucositis from cancer and its treatment. In the immunocompromised patient, no manipulation of the anus should occur, i.e., no rectal examinations, no suppositories, and no enemas. These actions can lead to the development of anal fissures or abscesses, which are portals of entry for infection. Also, the stoma of a patient with neutropenia should not be manipulated.
------------------------------------------------------------------------------- Bulk producers Bulk producers are natural or semisynthetic polysaccharide and cellulose. They work with the body's natural processes to hold water in the intestinal tract, soften the stool, and increase the frequency of the passage of stool. Bulk producers are not recommended for use in a regimen to counteract the bowel effects of opioids. Onset: 12 to 24 hours (may be delayed up to 72 hours) Caution: Take with 2 full 8-oz (150-200 mL) glasses of water and maintain adequate hydration to avoid the risk of developing a bowel obstruction. Avoid administering psyllium with salicylates, nitrofurantoin, and digitalis because psyllium decreases the actions of these drugs. Avoid use if intestinal obstruction is suspected. Use: Effective in managing irritable bowel syndrome. Drugs and dosages: methylcellulose: 5 to 20 cc 3 times per day with water (Cologel) barley malt extract: 4 tablets with meals and at bedtime or 2 T powder or (Maltsupex) liquid 2 times per day for 3 to 4 days, then 1 to 2 T at bedtime psyllium: varies from 1 T to 1 packet, depending on brand, 1 to 3 times per day Fiber-Malt: 1 T 2 or 3 times daily; 1 to 3 times daily for children 4 to 12 years of age; not to be given to children younger than 4 years of age (T = tablespoonful) ------------------------------------------------------------------------------ Saline laxatives The high osmolarity of the compounds in saline laxatives attracts water into the lumen of the intestines. The fluid accumulation alters the stool consistency, distends the bowel, and induces peristaltic movement. Cramps may occur. Onset: 0.5 to 3 hours Caution: Repeated use can alter fluid and electrolyte balance. Avoid magnesium-containing laxatives in patients with renal dysfunction. Avoid sodium-containing laxatives in patients with edema, congestive heart failure, megacolon, or hypertension. Use: Used mostly as a bowel preparation to clear the bowels for rectal or bowel examinations. Drugs and dosages: magnesium sulfate: 15 g in a glass of water milk of magnesia: 10 to 20 cc if concentrated, 15 to 30 cc if regular magnesium citrate: 240 cc sodium phosphate: 4 to 8 g dissolved in water mono- and di-basic sodium phosphate: 20 to 40 mL mixed with 4 oz cold water (Fleet Phospho-soda) ------------------------------------------------------------------------------ Stimulant laxatives Stimulant laxatives increase motor activity of the bowels by direct action on the intestines. Onset: 6 to 10 hours Caution: Prolonged use of these drugs causes laxative dependency and loss of normal bowel function. Prolonged use of cascara and danthrum discolors rectal mucosa and discolors alkaline urine red. Bisacodyl must be excreted in bile to be active and are not effective with biliary obstruction or diversion. Avoid bisacodyl with known or suspected ulcerative lesions of the colon. These medications may cause cramping. Drug interactions: Avoid taking bisacodyl within 1 hour of taking antacids, milk, or cimetidine because they cause premature dissolving of the enteric coating, which results in gastric or duodenal stimulation. There is an increased absorption of danthron when it is given with docusate. Use: Used to evacuate bowel for rectal or bowel examinations. Most of the stimulant laxatives act on the colon. Drugs and dosages: cascara sagrada: tablet (325-650 mg); fluid extract (1 cc); aromatic fluid extract (5 cc) danthron: 37.5 to 150 mg with or 1 hour after evening meal calcium salts of sennosides: 12 to 24 mg at bedtime senna: Senolax, Seneson, or Black-Draught (2 tablets); Senokot (2 tablets or 10-15 cc at bedtime); Casafru (5 cc) bisacodyl: 10 to 15 mg swallowed whole, not chewed, or 10 mg suppository ------------------------------------------------------------------------------- Lubricant laxatives Lubricant laxatives lubricate intestinal mucosa and soften stool. Caution: Administer on empty stomach at bedtime. Mineral oil prevents absorption of oil-soluble vitamins and drugs. With elderly patients, aspiration potential suggests that mineral oil should be avoided because it can cause lipid pneumonitis. It can interfere with postoperative healing of anorectal surgery. Avoid giving with docusate sodium. Docusate sodium causes increased systemic absorption of mineral oil. Use: Used prophylactically to prevent straining in patients for whom it would be dangerous to strain. Drugs and dosages: mineral oil: 5 to 30 cc at bedtime ------------------------------------------------------------------------------ Fecal softeners Fecal softeners promote water retention in the fecal mass, thus softening the stool. Up to 3 days may pass before an effect is noted. Stool softeners and emollient laxatives are of limited use because of colonic resorption of water from the forming stool. Fecal softeners should not be used as the sole regimen but may be useful given in combination with stimulant laxatives. Caution: May increase the systemic absorption of mineral oil when administered together. Use: Used prophylactically to prevent straining. Most beneficial when stool is hard. Drugs and dosages: docusate sodium: 50 to 240 mg taken with a full glass of water docusate calcium: 240 mg each day until bowel movement is normal docusate potassium: 100 to 300 mg each day until bowel movement is normal; should increase daily fluid intake Polaxer: 188 mg (480 mg at bedtime) ------------------------------------------------------------------------------ Lactulose (Cholac, Cephulac) Lactulose is a synthetic disaccharide that passes to the colon undigested. When it is broken down in the colon, it produces lactic acid, formic acid, acetic acid, and carbon dioxide. These products increase the osmotic pressure, thus increasing the amount of water held in the stool, which softens the stool and increases the frequency of passage. Onset: 24 to 48 hours Caution: Excessive amounts may cause diarrhea with electrolyte losses. Avoid giving with acute abdomen, fecal impaction, or obstruction. Dosage: 15 to 30 cc each day (contains 10-20 g of lactulose). Polyethylene glycol and electrolytes (Golytely, Colyte) Five packets are mixed with 1 gallon (3.785 liters) of tap water and contain the following: polyethylene glycol (227.1 g), sodium chloride (5.53 g), potassium chloride (2.82 g), sodium bicarbonate (6.36 g), and sodium sulfate (anhydrous) (21.5 g). Do not add flavorings. Serve chilled to improve palatability. Can be stored up to 48 hours in the refrigerator. Use: Used to clear bowel with minimal water and sodium loss or gain. -------------------------------------------------------------------------------
When abdominal distention occurs, movement of the diaphragm is compromised, leading to insufficient aeration with subsequent hypoxia and left ventricular dysfunction. Hypoxia can, in turn, precipitate angina or tachycardia. If the vaso-vagal response is stimulated by the pressure of impaction, the patient may become dizzy and hypotensive.
Movement of stool around the impaction may result in diarrhea, which can be explosive. Coughing or activities that increase intra-abdominal pressure may cause leakage of stool. The leakage may be accompanied by nausea, vomiting, abdominal pain, and dehydration and is virtually diagnostic of the condition. Thus, the patient with an impaction may present in an acutely confused and disoriented state, with signs of tachycardia, diaphoresis, fever, elevated or low blood pressure, and/or abdominal fullness or rigidity.
If a diagnosis of fecal impaction is uncertain, a laboratory work-up can rule out other problems. A complete blood cell count, appropriate blood chemistries, chest x-ray, and an electrocardiogram can be performed. If the patient has become dehydrated, the blood urea nitrogen, creatinine, and serum osmolality will be elevated. There may be an elevation of the hemoglobin and hematocrit indicating hemoconcentration. The white blood cell count (WBC) may be slightly elevated in the presence of a fever. If the WBC count is extremely elevated and the patient is exhibiting a high fever and abdominal pain, an obstruction, perforation, infection, or inflammatory process must be ruled out. With marked distention of the cecum (12 cm diameter or more), there is a risk of bowel perforation.
Nonstimulating bowel softeners, such as docusate, can be used to help soften stool higher in the colon. Mineral or olive oil can be given to loosen the stool. Caution should be used when giving docusate sodium with mineral oil because there could be an increased systemic absorption of the mineral oil leading to systemic lipid granulomas. Glycerin suppositories can also be used. Any laxatives that might stimulate the bowel or cause cramping should be avoided so that the bowel is not damaged further.
The obstructing mechanism can be mechanical or nonmechanical. Mechanical factors can be anything that causes a narrowing of the intestinal lumen (e.g., inflammation or trauma to the bowel, neoplasms, adhesions, hernias, volvulus, or a compression from outside the intestinal tract). Nonmechanical factors include those that interfere with the muscle action or innervation of the bowel: paralytic ileus, mesenteric embolus or thrombus, and hypokalemia.
Eighty percent of bowel obstructions occur in the small intestine; the other 20% occur in the colon. Bowel obstructions are frequently seen in the ileum. Small bowel obstructions are caused frequently by adhesions or hernias, whereas large bowel obstructions are caused commonly by carcinomas, volvulus, or diverticulitis. The presentation of obstruction will relate to whether the small or large intestine is involved.
When bowel obstruction is partial, decompression of the distended bowel may be attempted with nasogastric or intestinal tubes. Although use of these tubes may be successful in reducing edema, relieving fluid and gas accumulation, or decreasing the need for multiple stage procedures, surgery may be necessary within 24 hours if there is complete, acute obstruction.
For some patients with malignant obstructions of the gastrointestinal tract, the use of expandable metal stents may provide palliation of obstructive symptoms. Available stents include esophageal, biliary, gastroduodenal, and colorectal.[9-12] Stents may be placed under endoscopic guidance, using fluoroscopy. Morbidity with stent placement may be lower than with surgery. Adequate imaging of the stricture itself and the gastrointestinal tract distal to the stricture is recommended to assess stricture length, detect multifocal disease, and determine the appropriateness of stenting.[13,14]
In situations where neither surgery nor stenting is possible, the accumulation of the unabsorbed secretions produce nausea, vomiting, pain, and colicky activity as a consequence of the partial or complete occlusion of the lumen. In this case, a gastrostomy tube is commonly used to provide decompression of air and fluid that may be accumulating and causing visceral distention and pain. Such a tube is placed into the stomach and is attached to a drainage bag with the apparatus easily concealed under clothing. When the valve between the gastrostomy tube and the bag is open, the patient may be able to eat or drink by mouth without creating discomfort since the food is drained directly into the bag. Dietary discretion is advised to minimize the risk of tube obstruction by solid food. If the obstruction improves, the valve can be closed and the patient may once again benefit from enteral nutrition.
Sometimes, decompression is difficult even with a gastrostomy tube in place. This may be due to the accumulation of fluid, since several liters per day of gastrointestinal secretions may be produced. To relieve continuous abdominal pain, opioid analgesics via continuous subcutaneous or intravenous infusion may be necessary. Effective antispasmodics in this situation include anticholinergics (such as hyoscine butylbromide)  and possibly corticosteroids as well as centrally acting agents. If the bowel obstruction is thought to be functional (rather than mechanical) in origin, metoclopramide is the drug of choice due to its prokinetic effects on the bowel. For complete bowel obstruction thought to be irreversible, a trial of an antispasmodic such as hyoscyamine may decrease bowel contractions and therefore, yield pain relief. Another option for management of refractory pain and/or nausea is the synthetic somatostatin-analogue octreotide. This agent inhibits the release of several gastrointestinal hormones and reduces gastrointestinal secretions.[16,17] Octreotide is usually given subcutaneously at 50 to 200 mcg 3 times per day and may reduce the nausea, vomiting, and abdominal pain of malignant bowel obstruction. For selected patients, the addition of an anticholinergic such as scopolamine may be helpful in reducing the associated painful colic of malignant bowel obstruction when octreotide alone is ineffective. When either is used as a single agent it is ineffective.[9,18-20] Corticosteroids are widely used in treating bowel obstruction but empirical support is limited. They may be useful as adjuvant antiemetics and analgesics in this setting given as dexamethasone at a starting dose of 6 to 10 mg subcutaneously or intravenously 3 to 4 times per day.[9,18] (Refer to the Nausea, Vomiting, Constipation, and Bowel Obstruction in Advanced Cancer section in the PDQ summary on Nausea and Vomiting.)
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