A 56-year-old male with a history of cardiovascular disease s/p coronary artery bypass grafting (CABG) developed new-onset left lower quadrant abdominal cramping on postoperative day two. At approximately eight hours, he experienced an urge to defecate, followed by bloody diarrhea. He remained hemodynamically stable and denied any other GI symptoms, including nausea, vomiting and fever. He has no prior history of GI bleeding and no chronic GI diseases. He had a normal colonoscopy two years ago. A CBC, CMP and GI consultation were obtained.
The most likely cause of his symptoms is:
A. Crohn’s disease
B. Colorectal cancer
C. Acute colonic ischemia
D. Hemorrhoids
The correct answer is C, acute colonic ischemia. This case will discuss only acute colonic ischemia.
Practice Pearls
Pathophysiology
Acute colonic ischemia results from alterations in the systemic circulation or from anatomic/functional changes in the mesenteric vasculature, leading to hypoperfusion and reperfusion injury. The colon is particularly vulnerable due to its relatively lower blood flow compared to the remainder of the GI tract.1,2
The three primary mechanisms of ischemic injury are2:
- Nonocclusive ischemia: Due to low-flow states or systemic hypoperfusion
- Arterial occlusion: From embolic or thrombotic events
- Mesenteric vein thrombosis: Rarely affects the colon; when present, it almost always affects the proximal colon
The “watershed” areas of the colon, which have limited collateral blood flow, such as the splenic flexure and rectosigmoid junction, are at risk for ischemic injury, especially related to hypoperfusion.1
Risk Factors
- Medications, including constipation-inducing medications, immunomodulators, illicit drugs (cocaine) and diuretics.1,2
- Other common risk factors include myocardial infarction, chronic kidney disease with or without hemodialysis, aortoiliac instrumentation/surgery, COPD, cardiopulmonary bypass and extreme exercise.1,2
Signs and Symptoms of Acute Colonic Ischemia
- Rapid onset of mild, cramping abdominal pain and tenderness over the affected area. The pain is often associated with an urge to defecate.1
- Mild to moderate amounts of rectal bleeding (bright red or maroon) or bloody diarrhea usually develop within 24 hours of the onset of abdominal pain.1,2 Bleeding without preceding pain can also occur.1
- Less common symptoms are vomiting, dizziness and syncope.2
- Three progressive phases of clinical stages have been described1:
- Hyperactive phase: Severe pain with frequent passage of bloody stools; blood loss is usually not severe.
- Paralytic phase: Pain becomes diffuse and continuous with increased abdominal tenderness.
- Shock phase: Gangrenous mucosal injury leads to massive fluid loss, shock and metabolic acidosis, requiring urgent surgical intervention (affects only 10 to 20 percent of patients).
Diagnosis
- Laboratory studies: CBC, CMP, LDH, CPK and amylase may aid in evaluation but lack specificity1
- CT of the abdomen with intravenous contrast—first-line imaging modality2
- Typical findings: Colonic wall thickening, segmental pattern (thumbprinting) and edema1,2
- Advanced disease: Pneumatosis coli (air within the colon wall), gas in the mesenteric or portal veins, or pneumoperitoneum1,2
- Colonoscopy with minimal insufflation within 48 hours should be performed to confirm the diagnosis2
- Findings: Edematous, friable mucosa with erythema, interspersed pale areas, bluish hemorrhagic nodules, or in severe cases, marked cyanotic mucosa and scattered hemorrhagic erosions or linear ulcerations.
- Biopsies should be obtained, except in cases of gangrene.2
Treatment
Risk factors associated with a poor outcome include male sex, hypotension, abdominal pain without rectal bleeding, BUN>20, HgB<12, LDH>350, serum sodium <136 and WBC>15,000 cells/microliter.1,2
Management Based on Severity:
- Mild disease: Typical symptoms with imaging/colonoscopy findings consistent with colonic ischemia but no poor prognostic factors → Supportive care
- Moderate disease: Typical symptoms with up to three poor prognostic factors → Supportive care and empiric antibiotics. Consider antithrombotic therapy in the correct clinical scenario.
- Severe disease: More than three poor prognostic factors or any of the following: peritoneal signs on physical exam, pneumoperitoneum, pneumatosis, portal vein gas on radiologic imaging; gangrene on colonoscopic exam → Supportive care, antibiotics and urgent surgical consultation.
Supportive care includes bowel rest, IV fluids and close observation.
Antibiotics
- Empiric broad-spectrum coverage (e.g., piperacillin-tazobactam 3.375 g IV every six hours) is recommended for most patients with colonic ischemia, except in mild cases without bleeding.1
Antithrombotic Therapy
- Antithrombotic therapy is not indicated for most patients with acute colonic ischemia. However, antithrombotic therapy is indicated for acute colonic ischemia secondary to mesenteric venous thrombosis or related mesenteric thromboembolism.1
Surgical intervention is required in up to 20 percent of patients with acute colonic ischemia.1
References
- Grubel P, Lamont T, Nandakumar G. Colon ischemia. UpToDate. Updated Jul 24, 2024. https://www.uptodate.com/contents/colonic-ischemia
- Brandt LJ, Feuerstadt P, Longstreth GF, Boley SJ; American College of Gastroenterology. ACG clinical guideline: epidemiology, risk factors, patterns of presentation, diagnosis, and management of colon ischemia. Am J Gastroenterol. 2015;110:18-44.
 | Sarah Enslin, PA-C, is a physician assistant at the University of Rochester Medical Center in Rochester, NY, with over 10 years of experience as a practicing PA in GI. Sarah serves on several national GI committees and is a former member of the ASGE Practice Operations Committee and a current member of the ASGE APP Committee. |
 | Joseph Vicari, MD, MBA, FASGE, joined Rockford Gastroenterology in 1997 and has served as managing partner. He previously served as chair of the ASGE Practice Operations Committee, councilor on the ASGE Governing Board and currently serves as co-chair of the ASGE APP Committee. |