Would the white blood cell (WBC) count be elevated in acute diverticulitis?

Would the WBC be elevated with diverticulitis?

Yes, white blood cell (WBC) count is commonly elevated in acute diverticulitis and is routinely measured as part of the diagnostic workup, though it has limited value for distinguishing complicated from uncomplicated disease or predicting severity. 1

Role of WBC in Diagnosis

WBC count is included in the standard laboratory assessment for patients with suspected acute diverticulitis, alongside C-reactive protein (CRP), as part of evaluating inflammatory markers. 1 The 2020 World Society of Emergency Surgery (WSES) guidelines recommend a complete assessment using clinical history, signs, and laboratory inflammation markers including WBC count. 1

Expected Findings

• Leukocytosis is present in approximately 90% of patients with acute diverticulitis, making it a common but not universal finding. 2
• WBC >15 × 10⁹ cells/L is considered a high-risk feature that may warrant antibiotic treatment even in otherwise uncomplicated disease. 3, 4
• In younger patients (under 40 years), leukocytosis was documented in 90% of cases in one study. 2

Critical Limitations of WBC Count

WBC count has poor discriminatory value for disease severity. Multiple studies demonstrate that while WBC is often elevated, it cannot reliably distinguish complicated from uncomplicated diverticulitis:

• Area under the ROC curve of only 0.59 for discriminating acute diverticulitis from other causes of abdominal pain—essentially no better than chance. 5
• WBC count and body temperature are of no value in discriminating complicated from uncomplicated diverticulitis, according to a 426-patient study. 6
• Only CRP was an independent predictor of severe disease when multiple laboratory parameters were analyzed. 7

Why WBC Has Limited Utility

The key issue is that WBC can be elevated in both mild and severe disease, making it unreliable for risk stratification. 6 Additionally, normal WBC does not exclude complications—patients can have perforation or abscess formation with normal inflammatory markers, particularly early in the disease course when CRP has not yet risen (6-8 hour delay from symptom onset). 7

Clinical Algorithm for Using WBC

When to Measure WBC

• Obtain WBC count in all patients with suspected acute diverticulitis as part of initial laboratory workup (complete blood count, CRP, basic metabolic panel). 8

How to Interpret Results

If WBC >15 × 10⁹/L or rising leukocytosis:

• Consider this a high-risk feature favoring antibiotic treatment, even in uncomplicated disease 3, 4
• Lower threshold for CT imaging if not already obtained 3
• Consider hospitalization if combined with other risk factors (age >80, immunocompromised status, inability to tolerate oral intake) 3

If WBC is normal or mildly elevated:

• Do not use normal WBC to rule out diverticulitis or its complications 7, 6
• CT imaging remains essential for confirming diagnosis and assessing for complications, regardless of WBC level 7, 6
• Rely more heavily on CRP (>140-170 mg/L suggests higher risk of complicated disease) 1, 6

Common Pitfalls to Avoid

• Do not assume normal WBC excludes diverticulitis—clinical presentation and imaging are far more important. 7, 6
• Do not use WBC alone to determine disease severity—it has poor discriminatory ability between complicated and uncomplicated disease. 5, 6
• Do not delay CT imaging in patients with concerning clinical features just because WBC is normal, especially in immunosuppressed patients who may not mount a robust leukocyte response. 7
• Do not rely on WBC or temperature to guide management decisions—CRP is the only laboratory marker with sufficient diagnostic value for severity assessment. 6

Bottom Line for Clinical Practice

WBC is commonly elevated in diverticulitis (≈90% of cases) and should be measured, but it serves primarily as a nonspecific marker of inflammation rather than a tool for risk stratification. 1, 2 CRP >140-170 mg/L is far more useful for predicting complicated disease, and CT imaging with IV contrast remains the gold standard for diagnosis and severity assessment, regardless of laboratory values. 1, 7, 6