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492 SECTION 9: Gastrointestinal Disorders twice a day) are quite effective in inducing remission in mild to moder ate attacks of distal proctosigmoiditis and have lower systemic side effect profiles. If topical therapy is unsuccessful, oral glucocorticoids are effective in inducing a remission in the majority of cases. Daily doses of 40 to 60 milligrams of prednisone are usually sufficient and can be adjusted depending on the severity of the disease. Infliximab (5 milligrams/kg per dose) is the only biologic indicated for ulcerative colitis. It should be used in patients with mild to moderate disease who are corticosteroid dependent or refractory and in patients who have immunomodulator refractory disease. Hydrophilic bulk agents such as psyllium (Metamucil ® ) can be used in some patients to improve stool consistency. Antidiarrheal agents are generally ineffective and may precipitate toxic megacolon.  DISEASE COMPLICATIONS Blood loss from sustained hemorrhage is the most common complica tion, but toxic megacolon, which occurs in up to 10% of patients with ulcerative colitis, must not be missed. Toxic megacolon develops in advanced cases of colitis when the disease process extends through all layers of the colon ( Figure 73-1). This complication occurs in patients with severe ulcerative colitis. Toxic megacolon results from a loss of muscular tone within the colon, with dilatation and localized peritonitis. If the colon continues to dilate without treatment, signs of toxicity will develop. Plain radiography of the abdomen demonstrates a long, continuous segment of air-filled colon greater than 6 cm in diameter. Loss of colonic haustra and “thumb printing, ” representing bowel wall edema, may also be seen. The dis tended portion of the atonic colon can perforate, causing peritonitis and septicemia. Mortality is high. A patient with toxic megacolon appears severely ill; the abdomen is distended, tender, and tympanic. Severe diarrhea (>10 bowel move ments per day) is often seen but may have ceased. Fever, tachycardia, and hypotension are typically part of the clinical picture. Leukocytosis, anemia, electrolyte disturbances, and hypoalbuminemia are the sup porting laboratory results. FIGURE 73-1. Abdominal distention due to toxic megacolon. Arrows point to mucosal nodules. [Reproduced with permission from Schwartz DT (ed): Emergency Radiology: Case Studies. © McGraw-Hill, Inc., 2008. Chapter II-2, Fig. 23.] Some of the more prominent features of toxic megacolon, such as leukocytosis and peritonitis, can be masked in the patient taking cor ticosteroids. Antidiarrheal agents, hypokalemia, narcotics, cathartics, pregnancy, enemas, and recent colonoscopy have been implicated as precipitating factors in toxic megacolon. Medical therapy with nasogastric suction, IV prednisolone 60 milligrams per day or hydrocortisone 400 milligrams per day, parenteral broad-spectrum antibiotics active against coliforms and anaerobes, and IV fluids should be attempted as initial therapy, along with early surgical consultation. Cyclosporine A (4 milligrams/kg per day) and infliximab have been used as rescue therapy to prevent colectomy if steroids are not effective. 29 Cyclosporine A should not be given to patients with hypertension, renal impairment, epilepsy, sepsis, and age >80 years. Perirectal fistulas and abscesses may occur in up to 20% of patients with ulcerative colitis.

y) and infliximab have been used as rescue therapy to prevent colectomy if steroids are not effective. 29 Cyclosporine A should not be given to patients with hypertension, renal impairment, epilepsy, sepsis, and age >80 years. Perirectal fistulas and abscesses may occur in up to 20% of patients with ulcerative colitis. Massive GI hemorrhage, obstruction secondary to stricture formation, and acute perforation are other complications of the disease. There is a 10- to 30-fold increase in the development of carcinoma of the colon in patients with ulcerative colitis. The major risk factors for the development of carcinoma of the colon are extensive involvement and prolonged duration of the disease. The cumulative risk of cancer after 20 and 30 years is 5% to 10% and 12% to 20%, respectively. Additional factors that constitute increased risk of cancer in patients with ulcerative colitis include early onset of the disease and a family history of colon cancer.  DISPOSITION Patients with fulminant attacks of ulcerative colitis need hospitalization for aggressive fluid and electrolyte resuscitation and careful observation for the development of complications. Patients with complications such as GI hemorrhage, toxic megacolon, and bowel perforation must also be admitted with consultation to both a gastroenterologist and a surgeon. In addition to toxic megacolon, the indications for surgery include colonic perforation, massive lower GI bleeding, suspicion of colon cancer, and disease that is refractory to medical therapy (large doses of steroids required to control the disease). Patients with mild to moderate disease can be discharged from the ED. Close follow-up should be arranged with the patient’s physician or gastroenterologist, and any adjustment in medical therapy should be discussed prior to discharge. Acknowledgments: The authors gratefully acknowledge the contribu tions of Hagop S. Mekhjian, Douglas A. Rund, Annie T. Sadosty, and Jennifer J. Hess, the authors of this topic in the prior editions. REFERENCES The complete reference list is available online at www.TintinalliEM.com. Constipation Shawn R. Wassmuth Elizabeth C. Oehler INTRODUCTION AND EPIDEMIOLOGY Constipation is an extraordinarily common cause of patient morbidity.1-4 The incidence of constipation increases with age, with overall prevalence rates in North America from 12% to 19%.5 Constipation affects as many as 80% of critically ill patients and is directly associated with patient mortality in this population. Physicians and patients define constipation differently. Physicians have traditionally defined constipation as fewer than three bowel movements per week. Patients commonly define constipation in terms of symptoms such as abdominal discomfort, bloating, straining during CHAPTER Tintinalli_Sec09_p0473-0562.indd 492 8/2/19 6:49 PM

s and patients define constipation differently. Physicians have traditionally defined constipation as fewer than three bowel movements per week. Patients commonly define constipation in terms of symptoms such as abdominal discomfort, bloating, straining during CHAPTER Tintinalli_Sec09_p0473-0562.indd 492 8/2/19 6:49 PM CHAPTER 74: Constipation 493  PHYSICAL EXAMINATION Focused abdominal, pelvic, and rectal examinations are essential. Examine the patient for the presence of hernias and abdominal or pelvic masses. Bowel sounds will be decreased in cases of slow gut transit and increased in cases of obstruction. Ascites in the presence of constipation can be a sign of ovarian or uterine neoplasm in women. External rectal examination may demonstrate anal fissures, hemorrhoids, abscesses, or protruding masses. Digital rectal examination may demonstrate fecal impaction or an obstructing rectal mass. Watery stool making its way around a fecal impaction is common in elderly patients. Normal rec tal tone is useful in ruling out neurologic causes of obstruction. Stool retrieved from the rectal vault should be visually inspected and tested for occult blood. The finding of grossly bloody or guaiac-positive stool in the setting of constipation raises concern for cancer, bowel ischemia, stercoral ulcer, or inflammatory bowel disease.  LABORATORY EVALUATION AND IMAGING The evaluation of a constipated patient depends on the level of concern for organic causes. If the patient is chronically constipated, little is usu ally gained from any testing if the history and physical examination do not point toward a new organic cause. If the patient has a history concerning for intestinal obstruction (e.g., acute onset of symptoms, vomiting, significant abdominal distention or pain), abdominal flat and erect films (or left lateral decubitus films if the patient cannot stand) are useful. In cases of complete or partial intestinal obstruction, these films may demonstrate air-fluid levels or dilated bowel. If there continues to be high clinical suspicion for intestinal obstruction despite a normal chest and abdominal series of radiographs, then abdominal CT with PO and IV contrast may be necessary to make the diagno sis. In cases of suspected fecal impaction, an abdominal film should be obtained ( Figure 74-1). In a constipated patient, such a film will TABLE 74-1 Differential Diagnosis of Constipation Acute causes •   GI: bowel obstruction, quickly growing tumors, strictures, hernias, adhesions, inflammatory conditions, and volvulus •   Medicinal: narcotic analgesic, antipsychotic, anticholinergic, antacid, antihistamine •   Exercise and nutrition: decrease in level of exercise, fiber intake, fluid intake •   Painful anal pathology: anal fissure, hemorrhoids, anorectal abscesses, proctitis Chronic causes •   Gastrointestinal: slowly growing tumor, colonic dysmotility, chronic anal pathology •   Medicinal: chronic laxative abuse, narcotic analgesic, antipsychotic, anticholinergic, antacid, antihistamine •   Neurologic: neuropathies, Parkinson’s disease, cerebral palsy, paraplegia •   Endocrine: hypothyroidism, hyperparathyroidism, diabetes •   Electrolyte abnormalities: hypomagnesemia, hypercalcemia, hypokalemia •   Rheumatologic: amyloidosis, scleroderma •   Toxicologic: lead, iron, chronic opioid use bowel movements, or the sensation of incomplete evacuation. Consti pation should not be defined simply by stool frequency alone, because doing so can lead to underdiagnosis for a significant number of patients who suffer from the condition.

logic: amyloidosis, scleroderma •   Toxicologic: lead, iron, chronic opioid use bowel movements, or the sensation of incomplete evacuation. Consti pation should not be defined simply by stool frequency alone, because doing so can lead to underdiagnosis for a significant number of patients who suffer from the condition. 7 The Rome criteria for the definition of constipation consist of two or more of the following signs or symptoms: (1) straining at defecation at least 25% of the time, (2) hard stools at least 25% of the time, (3) incomplete evacuation at least 25% of the time, (4) fewer than three bowel movements per week, and (5) rarely having loose stools without the use of laxatives and having symptoms for at least 3 months in the preceding 6 months for chronic constipation. PATHOPHYSIOLOGY Constipation is a complicated condition with multiple, often overlap ping causes (Table 74-1). Gut motility is affected by diet, activity level, anatomic lesions, neurologic conditions, medications, toxins, hormone levels, rheumatologic conditions, microorganisms, and psychiatric conditions. Constipation is best thought of as either acute or chronic, as doing so helps formulate a differential diagnosis (Table 74-1). Acute constipation should primarily prompt evaluation for intestinal obstruction, and history and physical examination can identify other causes. Chronic constipation can be caused by many of the same conditions that cause acute constipation (Table 74-1). CLINICAL FEATURES  HISTORY The differential diagnosis of constipation is broad, so obtain a thorough history. Determine when the symptoms started and if there are any temporally related clues that can help narrow the differential diagnosis. Was a new medication or dietary supplement added at that time? Was there a decrease in fiber or fluid intake? Was there a change in activity level? Past medical and family history can help shed light on the cause of the constipation. Is there a history of hypothyroidism or diabetes? Identify past abdominal surgical procedures. Does the patient have frequent kidney stones, which might point to hyperparathyroidism? Although most patients who present with constipation do not have emergent conditions and may be treated symptomatically as outpatients, there are several historical elements that hint to a more ominous cause of symp toms, such as intestinal obstruction. Worrisome findings, in addition to constipation, include rapid onset, nausea or vomiting, inability to pass flatus, severe abdominal pain and distention, unexplained weight loss, rectal bleeding, unexplained iron deficiency anemia, or a family history of colon cancer. 2 Consider ovarian carcinoma in women with new concerning symptoms of obstruction or bloating. Any of these findings should prompt a more rigorous evaluation. Diarrhea does not rule out constipation/obstruction, as liquid stool can move past an obstructive source. FIGURE 74-1. Large bowel obstruction due to fecal impaction (F). [Reused with permission from Schwartz DT (ed): Emergency Radiology: Case Studies. © McGraw-Hill, Inc., 2008. Chapter II-2, Fig. 19.] Tintinalli_Sec09_p0473-0562.indd 493 8/2/19 6:49 PM

tion/obstruction, as liquid stool can move past an obstructive source. FIGURE 74-1. Large bowel obstruction due to fecal impaction (F). [Reused with permission from Schwartz DT (ed): Emergency Radiology: Case Studies. © McGraw-Hill, Inc., 2008. Chapter II-2, Fig. 19.] Tintinalli_Sec09_p0473-0562.indd 493 8/2/19 6:49 PM 494 SECTION 9: Gastrointestinal Disorders demonstrate colonic or rectal dilation with or without air-fluid levels. Normal maximum diameter of the colon is 6 cm, whereas normal maximum diameter of the rectum is 4 cm. 2 In all patients in whom an organic cause of constipation is suspected, laboratory evaluation should include a CBC to screen for anemia, and electrolytes to evaluate for hypomagnesemia, hypercalcemia, and hypokalemia. Obtain thyroid function tests for suspected hypothyroidism. Obtain serum lead and iron levels for suspected heavy metal toxicity. SPECIAL CONSIDERATIONS  FUNCTIONAL CONSTIPATION The treatment of chronic (functional) constipation is best managed using a multidisciplinary approach. Unfortunately, there is no simple medication fix for this common problem. Emergency medicine providers are encouraged to stress lifestyle and diet modification. A strict dietary and exercise regimen is important, because without adequate fluid (1.5 L per day), fiber (10 grams per day), and exercise, medicinal treatments usually fail. 4 The bulking agent psyllium can improve bowel movement frequency in adults with chronic constipation. Osmotic laxatives such as polyethylene glycol and lactulose have been shown in randomized controlled trials to be effective at improving stool frequency in patients. 9 Newer prescription drugs that stimulate GO motility via the serotonin 4 receptor (prokinetics), as well as agents that directly stimulate intestinal secretion to increase stool water content (colonic secretagogues), are being marketed. Medications often employed in the treatment of constipation are listed in Table 74-2. Although some evidence supports polyethylene glycol as a first-line agent in children, the literature does not clearly demonstrate the superiority of any one laxative for use in pediatric patients.11 Also, there is no gold standard management of constipation in palliative care and no evidence to support the use of one laxative, or combinations of laxatives, over another. 12 There has been some promise recently with the use of subcutaneous methylnaltrexone and oral naloxegol in multiple studies of patients with opioid-induced constipation. 13-18 The effectiveness of rectal irrigation for functional bowel disorders has not been clearly demonstrated in prospective trials. Nevertheless, the procedure is felt to be safe and will benefit some patients. 16 In its extreme form, functional constipation can result in a variety of potentially life-threatening complications, especially fecal impaction and intestinal pseudo-obstruction (Ogilvie’s syndrome 19,20).  OPIOID-INDUCED BOWEL DYSFUNCTION Opioid-induced bowel dysfunction is a common complication of longterm opioid therapy, which affects 40% to 80% of patients. 16,17 Novel treatments for opioid-induced constipation, such as purely peripher ally acting mu-opioid receptor antagonists, work to decrease the con stipating effects of opioids without reversing their central analgesic effects. 18,21,22 These medications can be useful when conventional laxa tive treatments are ineffective.

Novel treatments for opioid-induced constipation, such as purely peripher ally acting mu-opioid receptor antagonists, work to decrease the con stipating effects of opioids without reversing their central analgesic effects. 18,21,22 These medications can be useful when conventional laxa tive treatments are ineffective. TABLE 74-2 Medical Adjuncts for the Treatment of Constipation Type Generic Name Trade Name PRN Doses Side Effects Mechanism Fiber Psyllium Metamucil® 1 teaspoon three times a day Bloating, flatulence Increases stool bulk or transit time Emollient Docusate sodium Colace® 100 milligrams daily/twice a day Cramping Facilitates mixture of stool fat and water Stimulants Bisacodyl Anthraquinones Senna Dulcolax ® Peri-Colace® Senokot® , Ex-lax® 10 milligrams PR three times a day One to two tablets PO daily/twice a day Two tablets PO daily/twice a day or 15–30 mL daily/twice a day Incontinence, rectal burning Melanosis coli, degeneration of myenteric plexus Laxative abuse, nausea, melanosis coli, cramping Stimulates the myenteric plexus, thereby increasing intestinal motility Saline laxative Magnesium Milk of magnesia Magnesium citrate 15–30 mL daily/twice a day 100–240 mL daily/twice a day Magnesium toxicity, especially in renal insufficiency Cramping, flatulence, hypermagnesemia May decrease colonic transit time; osmotic laxative Suppository Glycerin suppository NA 1 PR daily Rectal irritation Local rectal stimulation Hyperosmolar agents Lactulose Sorbitol Polyethylene glycol GoLYTELY ® MiraLAX® 15–30 mL daily/twice a day 15–30 mL daily/twice a day 1 gallon/4 h 17 grams daily, onset of effect 1–3 days Cramps, flatulence, belching, nausea Cramps, flatulence Nausea, cramping, anal irritation Osmotically active nonabsorbable sugars pull fluid into the gut Enemas Mineral oil Tap water Soap suds Monophosphate Fleets ® 100–250 mL PR 500 mL PR 1500 mL PR 1 unit PR Local trauma Local trauma Local trauma Local trauma, hyperphosphatemia (especially in patients with renal failure) Colonic distention encourages evacuation Serotonergic agents Prucalopride Resolor ® 2 mg daily Nausea, diarrhea Stimulates GI motility Prosecretory agents Lubiprostone Amitiza® 24 micrograms twice a day Nausea, diarrhea Stimulates the movement of ions and water into the lumen Peripherally acting mu-opioid receptor antagonists Naloxegol Movantik ® 25 milligrams daily Abdominal pain Mu-opioid receptor antagonist Abbreviations: NA = not applicable; PRN = as needed. Tintinalli_Sec09_p0473-0562.indd 494 8/2/19 6:49 PM