Gastroenterology Hepatology

Ischemic colitis

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How can I be sure that the patient has ischemic colitis?

Ischemic colitis most commonly presents with the sudden onset of mild cramping abdominal pain and the urgent desire to defecate. The patient usually passes bright red or maroon blood per rectum with diarrhea within 24 hours of symptom onset. There is usually mild-to-moderate abdominal tenderness over the segment of bowel that is involved. In patients who have isolated ischemic colitis of the right-colon (e.g. cecum and/or ascending colon), abdominal pain may be severe and occur without obvious rectal bleeding. To diagnose ischemic colitis, use history and physical findings with appropriate imaging (e.g., Computed Tomography with oral and IV contrast) and other diagnostic tests (e.g., colonoscopy when indicated).

What history is important to obtain from the patient?

In any patient presenting with bright red blood per rectum, or lower abdominal pain, the clinician should ask about recent medication exposures (e.g., immunomodulators, constipation-inducing medications), medical co-morbidities (e.g., peripheral vascular disease, colon cancer, chronic obstructive pulmonary disease), accompanying diarrhea, tenesmus, and fever, the timing of passage of red blood per rectum, the volume of blood passed, history of similar symptoms in the past, and the acuity of onset, character, and location of the abdominal pain.

Pathognomonic or characteristic features

The characteristic features include cramping abdominal pain in the distribution of affected colon, followed by a short course of bloody diarrhea. There are no pathognomonic features of ischemic colitis.

See Table I for signs and symptoms of ischemic colitis.

Table I.

Signs and symptoms of ischemic colitis

Less common clinical presentations

Ischemic colitis can present in various ways including reversible colopathy, transient colitis, chronic colitis, stricture and gangrene. Irreversible manifestations include chronic colitis (chronic watery or bloody diarrhea), stricture (large bowel obstruction) and gangrene (abdominal pain).

Differential diagnoses

A broad differential diagnosis is useful when diagnosing ischemic colitis because many colitides can present similarly to colon ischemia, and more than one disease process may be present. (See Table II.)

Table II.

Differential diagnoses

What is the difference between acute mesenteric ischemia and ischemic colitis?

Acute mesenteric ischemia results from inadequate blood flow to all or part of the small intestine and may involve the right half of the colon, within the distribution of the superior mesenteric artery. The spectrum of injury in acute mesenteric ischemia ranges from transient alteration of bowel function to gangrene. Acute mesenteric ischemia commonly results from an embolus (superior mesenteric artery) or a low flow state (nonocclusive mesenteric ischemia), although a thrombus (superior mesenteric artery or superior mesenteric vein) can be the etiology as well. Patients with acute mesenteric is commonly present with an elevated white blood cell count (approximately 12,000-15,000 cells/mm3) and CT angiogram is the diagnostic modality of choice to assess for a clot in the arteries or veins, of the small bowel, and to evaluate small bowel wall thickening.

Ischemic colitis in contrast involves the colon and has a wide spectrum of presentation. Ischemic colitis occurs within the distribution of the superior mesenteric artery (right colon through transverse colon) or inferior mesenteric artery (transverse colon to the rectum).

Acute mesenteric ischemia is associated with a high mortality rate, while ischemic colitis has a generally good prognosis. Isolated-right sided ischemic colitis (IRCI) has a worse prognosis than all other patterns of involvement of ischemic colitis. Acute mesenteric ischemia can either occur with or after IRCI, an occurrence that has the worse prognosis of ischemic colitis regardless of location of colon affected.

How can I confirm the diagnosis?

What tests should be ordered first?

Blood tests and stool studies are useful first tests to assess for ischemic colitis. Blood tests should include complete blood count, basic metabolic panel and liver biochemical profile; stool studies should include culture, testing for C. difficile, and ova and parasite examination. If the patient appears acutely ill, the clinician should consider obtaining a serum lactate level, bicarbonate, sodium, lactate dehydrogenase, creatine kinase, and amylase level.

What tests should be used to confirm the initial tests?

Repeat testing, as above, is indicated to follow the patient's condition and course.

A CT scan of the abdomen and pelvis can show a segmental colitis or complications including "free air" and pneumatosis coli, as well as thrombi in the arteries or veins. If intravenous contrast is given, the CT scan also can help determine if bowel still has blood supply and if the bowel is "dead." If the patient is presenting with severe abdominal pain with or without rectal bleeding, they have severe right-sided pains and/or they appear acutely ill, consider a CT-angiogram for a more accurate assessment of the vascular supply to the bowel.

If the diagnosis is suspected but unclear, colonoscopy within 48 hours of presentation should be considered unless the patient has signs of acute peritonitis or evidence or irreversible ischemic damage. Colonoscopy may reveal subepithelial hemorrhage or edema or, if more than 48 hours after onset, ulcerations. Biopsies should be obtained during colonoscopy in all circumstances except gangrene.

It is important to remember that there is no ideal test for suspected colon ischemia. Any of these tests may support the diagnosis but none can provide actual confirmation, except biopsy in some circumstances. The clinician should choose a test based on the clinical scenario and the expertise of the department of radiology at his/her institution.

What tests are useful if diagnosis is still in doubt?

Although colonoscopy is the main diagnostic test today, it may not show conclusive results.

Biopsies should be obtained to characterize the disease and its segmental nature. Biopsies consistent with ischemic colitis might show subepithelial hemorrhage and edema, iron-laden macrophages, and submucosal fibrosis; only gangrene provides the diagnosis. Note that mesenteric angiography is not usually needed in patients with suspected ischemic colitis unless the patient has severe abdominal pain or is thought to have isolated involvement of just the cecum and/or ascending colon because of the coincidence or development of acute mesenteric ischemia.

A diagnostic algorithm

See Figure 1 for a diagnostic algorithm for ischemic colitis.

Figure 1.

When is it important to consult a gastroenterologist or surgeon?

It is most important to refer to a gastroenterologist and/or surgeon when patients present with an acute abdomen, the physical exam is remarkable for pain out of proportion to the exam, and the patient has blood work remarkable for an elevated lactate, lactate dehydrogenase, creatine kinase, substantial leukocytosis, or metabolic acidosis. Refer to a gastroenterologist when a patient presents with bloody diarrhea or bright red blood per rectum. Also, if the CT scan or angiogram shows an acute thrombus, embolus, or other cause of mesenteric ischemia or mesenteric venous thrombosis surgical (general, vascular), consultation should be obtained.

Which patients require hospitalization?

Patients who have severe abdominal pain, persistent bloody diarrhea, are hemodynamically unstable, or have any signs of bowel perforation or infarction should be hospitalized. All elderly patients presenting with symptoms consistent with ischemic colitis should be hospitalized and managed conservatively for 24 hours.

See Table III for a listing of laboratory, radiographic, and endoscopic tests.

Table III.

Diagnostic tests for ischemic colitis

What other diseases, conditions, or complications should I look for in patients with ischemic colitis?

Major risk factors and diseases predisposing to ischemic colitis

  • Age >60 years

  • Female gender

  • Atherosclerosis, congestive heart failure, chronic obstructive pulmonary disease, diabetes mellitus, hypertension, irritable bowel syndrome

  • Medication use, including alosetron, amiodarone, bisacodyl, buproprion, "constipation inducing drugs" (e.g., opioids, non-opioids), danazol, digitalis, ergot, estrogens, flutamide, furosemide, glycerin enema, gold salts, immunosuppressive agents, interferon, magnesium citrate, NSAIDs (nonsteroidal anti-inflammatory drugs), paroxetine, penicillin, phenylephrine, polyethylene glycol, alproic acid, progestins, pseudoephedrine, saline laxatives, statin medications, sumatriptan, TNF-α inhibitors, vasopressin

  • Illicit drug use, including cocaine, methamphetamine, psychotropic drugs

  • Smoking

Diseases associated with ischemic colitis

  • Amyloidosis

  • Cardiac failure or arrhythmias

  • Chronic obstructive pulmonary disease

  • Hematologic coagulopathies

  • Hypertension

  • Pancreatitis

  • Peripheral vascular disease

  • Pheochromocytoma

  • Ruptured ectopic pregnancy

  • Shock

  • Sources of arterial emboli

  • Strangulated hernia

  • Vasculitis

  • Volvulus

Commonly encountered complications

There are various clinical sequelae of ischemic colitis. These include reversible colopathy (most common), transient colitis, chronic colitis, stricture, gangrene, and universal/fulminant colitis.

The initial presentation for each of these sequelae is usually the same and does not predict the clinical course of disease. The exception to this rule is disease isolated to the right-colon, which is associated with more severe disease and a worse prognosis.

Symptoms of colonic ischemia generally resolve in 48 to 72 hours with colonic healing in 1 to 2 weeks (reversible colopathy and transient colitis). Symptoms persisting for more than 2 weeks are associated with a higher incidence of gangrene, perforation, segmental ulcerating colitis, or stricture. Chronic colitis is a rare manifestation of chronic colon ischemia.

What is the right therapy for the patient with ischemic colitis?

Effective treatment options

Intravenous fluids, antibiotics, and surgical intervention are all effective treatments in the appropriate clinical setting.

Treatment options

Intravenous fluid administration is the best nondrug therapy for ischemic colitis. All patients admitted with ischemic colitis should receive intravenous fluids. This will increase circulating intravascular volume and improve bowel perfusion, thereby preventing further episodes of ischemia.

Antibiotic therapy is indicated in ill patients hospitalized with advanced ischemic colitis. Antibiotics should cover gut flora, including gram-negative rods and anaerobes.

Surgical therapy is needed in a minority of patients who present acutely with ischemic colitis. Patients requiring emergent surgical intervention include those with signs of peritonitis, massive bleeding, portal venous gas and/or pneumatosis on imaging, universal fulminant colitis, with or without megacolon and deteriorating clinical conditions. Some patients will require nonemergent surgical intervention. These include patients with continued symptoms for 2 or more weeks, persistent protein-losing colopathy, and those with recurrent sepsis because of bacteria that seed the bloodstream via the damaged colon lining ("bacterial translocation"). Patients with irreversible manifestations of colonic ischemia, including stricture formation with obstruction and chronic colitis with diarrhea and rectal bleeding, also may require surgery.

What is the most effective initial therapy?

The most effective initial therapy is intravenous fluids. This will increase circulating intravascular volume and improve bowel perfusion. Give a bolus of isotonic fluid to correct fluid depletion, followed by a maintenance infusion. If the patient has a contraindication to fluids (e.g., congestive heart failure), initiate gentle hydration and maintain a low rate. Continue intravenous fluids for 24 or 48 hours, always being mindful of fluid overload. Consider broad spectrum antibiotics in addition to fluids for patients with up to three of the following factors:

  • Male gender

  • Hypotension (systolic blood pressure < 90 mmHg)

  • Tachycardia (heart rate > 90 beats/min)

  • Abdominal pain without rectal bleeding

  • BUN > 20 mg/dl

  • Hgb < 112 g/dl

  • LDH > 350 U/l

  • Serum sodium < 136 mEq/l (mmol/l)

  • WBC > 15 cells/cmm (x109/l)

  • Colonic mucosal ulceration identified on colonoscopy

Patients with more than three of the factors listed above, should receive intravenous fluids, antimicrobials, have correction of cardiovascular abnormalities, be seen emergently by the surgical service and transferred to the intensive care unit for appropriate monitoring.

There are no randomized controlled trials of intravenous fluids or antibiotics for ischemic colitis. Recommendations are based on expert consensus.

Listing of usual initial therapeutic options, including guidelines for use, along with expected result of therapy.

With fluid administration, the patient's bloody diarrhea should subside in 24 to 48 hours. The patient should also have improvement in cramping abdominal pain within 24 hours of intravenous fluid hydration for treatment.

The clinician should optimize medications to maximize colonic blood perfusion. Blood pressure medications should maintain the patients' systolic blood pressure over 120 mmHg. Congestive heart failure medications should be titrated to improve forward blood flow.

If a patient is hospitalized for ischemic colitis, especially with severe or persistent symptoms, consider giving antibiotic therapy. The antibiotic therapy should treat gut flora, including gram-negative rods and anaerobes. Possible treatment regimens include fluoroquinolone or aminoglycoside or third-generation cephalosporin plus anti-anaerobe coverage. Use antibiotics for a minimum of 72 hours; if the patient does not improve after 72 hours, consider broadening the antibiotic coverage and continuing treatment.

If patients do not symptomatically improve in the first 24 to 48 hours or if they have complicated or severe disease, consider referral to a gastroenterologist.

If initial therapy with intravenous fluids and/or antibiotics fails or the patient has severe disease with an acute abdominal exam, then surgical intervention is usually indicated. Treatment failure can be defined by a lack of improvement within 48 to 72 hours of symptom onset or a worsening of symptoms during that time period.

Obtain surgical consultation in patients with peritoneal signs, massive bleeding, portal venous gas and/or pneumatosis on imaging, universal fulminant colitis with or without toxic megacolon and deteriorating clinical condition. When the patient has been diagnosed with a vascular stenosis or occlusion of the intestinal arteries, consider consulting a vascular surgeon for endovascular or other surgical treatments.

Nonemergent surgical laparotomy is indicated in patients with continued symptoms despite conservative measures after 2 to 3 weeks following onset, persistent protein losing colopathy, or in those with overall symptomatic improvement but with recurrent bouts of sepsis.

A listing of a subset of second-line therapies, including guidelines for choosing and using these salvage therapies

What is the rationale behind using antibiotic therapy?

Some authors believe that antibiotics prevent gut flora translocation because the episode of ischemia will lead to ulceration and access of the gut flora to the blood supply. Other investigators believe that antibiotics serve a different but unspecified protective mechanism and that using the medications can prevent a worse outcome (i.e., colectomy, mortality).

Studies assessing the effectiveness of antibiotics are limited and based on data using canine and mouse models. Models show less inflammation with use of antibiotics. Of note, there are no set guidelines for the type, dosage, or duration of antibiotic treatment and the information presented is based on expert recommendations.

How often is surgical management needed and what is the mortality rate?

Surgical management has been estimated to be required in up to 2% of patients admitted to the hospital with ischemic colitis. In patients who underwent surgical intervention for ischemic colitis, the mortality rate was up to 50% for those patients who had infarcted bowel at the time of surgery.

Listing of these, including any guidelines for monitoring side effects.

Side effects from antibiotic therapy

Ciprofloxacin. Rash, nausea, vomiting, diarrhea, abdominal pain, headache, increased AST/ALT, increased serum creatinine, tendon rupture, and arthropathy

Metronidazole. Headache, nausea, vomiting, diarrhea, dizziness, loss of appetite, metallic taste in the mouth, and neuropathy

Gentamicin. Nephrotoxicity, auditory and vestibular ototoxicity, gait instability, neurotoxicity

Ceftriaxone. Pain or erythema at the injection site, rash, diarrhea, eosinophilia, thrombocytosis, elevated aminotransferases (AST/ALT), and elevated blood nitrogen urea (BUN)

How should I monitor the patient with ischemic colitis?

The clinician must always consider that patients with ischemic colitis might form a stricture or develop chronic colitis. Stricture formation might present in a variety of ways including constipation, narrowing caliber of stool, or large bowel obstruction. This can be assessed with either a CT scan or barium enema. If a patient's stricture is clinically significant surgical resection may be indicated.

Chronic colitis may present with recurrent episodes of bloody diarrhea, chronic watery diarrhea, or a protein losing colopathy. It is unclear whether there is a connection between chronic colitis associated with ischemia and inflammatory bowel disease.

Follow-up recommendations

Patients with mild episodes of ischemic colitis can usually follow up with their physician within 1 month. During patient follow-up, the clinician should ask the patient about his/her bowel habits, the presence or absence of blood in stool, and abdominal pain. Persistent diarrhea or blood in the stool might indicate another disease process. It is usually not necessary to repate colonoscopy to assess healing if the patient has no symptoms of colitis.

A CBC should be obtained to monitor for anemia. The clinician also should reaffirm the importance of adequate hydration. If a medication that the patient was chronically being treated with was stopped because of ischemic colitis, a replacement medication should be started.

Patients who required surgical intervention will require closer follow-up and evaluation. These patients should be seen within 2 weeks of discharge from the hospital.

What information should patients be told about ischemic colitis?

It is important that patients understand that ischemic colitis is a self-limited disease usually lasting 24 to 48 hours and that it is unlikely to recur.

Patients should be encouraged to drink 8 glasses (2 liters) of water daily to maintain hydration, unless otherwise contraindicated (e.g., congestive heart failure).

If the patient has hypertension and is on a blood pressure medication, the patient must closely monitor his/her blood pressure to make sure it is well controlled.

Patients should have their medication lists reviewed with them. If a medication was changed, it is important to explain to the patient why this change occurred (e.g., associated with ischemic colitis). Patients should also be provided with information about alternative medication and be treated with whatever medications the gastroenterologist and primary care doctor decide is optimal.

What's the evidence?

Feuerstadt, P, Aroniadis, O, Brandt, LJ. "Features and Outcomes of Patients With Ischemia Isolated to the Right Side of the Colon When Accompanied or Followed by Acute Mesenteric Ischemia". Clin Gastroenterol Hepatol. vol. 13. 2015 Nov. pp. 1962-8.

(This retrospective study of 65 patients is a comparative analysis of the medical co-morbidities, diagnostic serology, imaging and outcomes of those with IRCI alone versus those with accompanying or subsequent development acute mesenteric ischemia.)

Brandt, LJ, Feuerstadt, P, Longstreth, GF, Boley, SJ. "ACG clinical guideline: Epidemiology, risk factors, patterns of presentation, diagnosis, and management of colon ischemia (CI)". Am J Gastroenterol. 2015. pp. 110-18.

(These clinical guidelines from the ACG discussing colon ischemia, published in 2015)

Brandt, LJ, Feuerstadt, P, Blaszka, M. "Anatomic patterns, patient characteristics and clinical outcomes in ischemic colitis: a study of 313 cases supported by histology". Am J Gastroenterol. vol. 105. 2010. pp. 2245-52.

(This retrospective study of 313 patients with biopsy-proven ischemic colitis and complete colonoscopic or radiologic evaluation of disease distribution provides a comparative analysis of medical comorbidities, presentations, and outcomes of ischemic colitis, based on which segments of the colon are affected.)

Longstreth, GF, Yao, JF. "Epidemiology, clinical features, high-risk factors, and outcome of acute large bowel ischemia". Clin Gastroenterol Hepatol. vol. 7. 2009. pp. 1075-80.

(This retrospective study of 401 patients with colon ischemia offers a comprehensive primary analysis of the epidemiology, high-risk features, and outcomes of a cohort of patients with ischemic colitis.)

Feuerstadt, P, Brandt, LJ. "Update on Colon ischemia: recent insights and advances". Curr Gastroenterol Rep. 2015. pp. 17-45.

(This is a review article summarizing the most recent findings and advances in the field of ischemic colitis.)

Ibrahim, CB, Aroniadis, OC, Brandt, LJ. "On the role of ischemia in the pathogenesis of IBD: a review". Inflamm Bowel Dis. vol. 16. 2010. pp. 696-702.

(This clinical review article examines the etiologic roles of macro- and microvasculature and of intestinal ischemia in the pathogenesis of inflammatory bowel disease.)

Hass, DJ, Kozuch, P, Brandt, LJ. "Pharmacologically mediated colon ischemia". Am J Gastroenterol. vol. 102. 2007. pp. 1765-80.

(This article provides a comprehensive review of pharmacologically mediated ischemic colitis, including classes of medications commonly associated with ischemic colitis and their hypothesized mechanism of action.)
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