Diagnostic Criteria for Ulcerative Colitis Flare
The diagnosis of an ulcerative colitis flare requires a combination of clinical symptoms, laboratory markers, and endoscopic findings, with fecal calprotectin >150 mg/g being the most reliable non-invasive marker to confirm active inflammation. 1
Clinical Assessment
Symptoms to Evaluate
- Rectal bleeding (frequency and severity)
- Stool consistency and frequency
- Urgency and tenesmus
- Abdominal pain
- Nocturnal diarrhea
- Incontinence 1
Physical Examination
- Vital signs: pulse, blood pressure, temperature
- Weight (check for recent weight loss)
- Abdominal examination for distension and tenderness
- Perianal inspection and digital rectal examination 1
Laboratory Investigations
Essential Tests
- Full blood count (look for anemia, thrombocytosis, leukocytosis)
- C-reactive protein (CRP)
- Fecal calprotectin (>150 mg/g indicates active inflammation)
- Fecal lactoferrin 1
Microbial Testing
- Always test for C. difficile infection with every disease flare 1
- Consider Cytomegalovirus testing in treatment-refractory cases 1
- Other stool pathogens should be excluded 1
Endoscopic Assessment
When to Perform Endoscopy
- For patients with mild symptoms and elevated inflammatory markers (fecal calprotectin >150 mg/g, elevated CRP), endoscopic assessment is recommended before treatment adjustment 1
- For patients with moderate to severe symptoms and elevated inflammatory markers, endoscopy may be avoided as these markers reliably indicate active inflammation 1
- In acute severe colitis, flexible sigmoidoscopy is sufficient (avoid full colonoscopy) 1
Endoscopic Features of Active UC
- Erythema
- Loss of vascular pattern
- Granularity
- Friability
- Bleeding
- Ulcerations 2
Diagnostic Algorithm for UC Flare
Initial Assessment:
- Evaluate clinical symptoms (rectal bleeding, stool frequency)
- Check inflammatory markers (fecal calprotectin, CRP)
- Rule out infectious causes (C. difficile, other pathogens)
If moderate to severe symptoms AND elevated inflammatory markers:
- Fecal calprotectin >150 mg/g OR
- Elevated fecal lactoferrin OR
- Elevated CRP
- Proceed with treatment adjustment without endoscopy 1
If mild symptoms AND elevated inflammatory markers:
- Perform endoscopic assessment before treatment adjustment 1
If acute severe symptoms:
- Perform flexible sigmoidoscopy with biopsies
- Avoid full colonoscopy and bowel purgatives 1
Severity Assessment
The Mayo scoring system is commonly used to assess disease severity and monitor treatment response, incorporating:
- Stool frequency
- Rectal bleeding
- Endoscopic appearance
- Physician's global assessment 2
Important Considerations
- No single "gold standard" exists for diagnosing UC flares 1
- Endoscopy with biopsies remains the reference standard for assessing disease activity but may not be necessary in all cases 1
- In patients with acute severe colitis, sigmoidoscopy is safer than full colonoscopy 1
- Fecal calprotectin correlates well with endoscopic indices of disease activity 1
Pitfalls to Avoid
- Do not rely solely on symptoms - clinical symptoms may not correlate with endoscopic severity 1
- Do not miss C. difficile infection - test with every flare as it can worsen outcomes 1
- Do not perform full colonoscopy in acute severe colitis - sigmoidoscopy is sufficient and safer 1
- Do not ignore elevated inflammatory markers in patients with mild symptoms - endoscopic assessment is recommended in these cases 1
By systematically evaluating clinical symptoms, laboratory markers, and when necessary, endoscopic findings, clinicians can accurately diagnose UC flares and initiate appropriate treatment to improve patient outcomes.