How should I manage a patient with abdominal pain and tenderness, diarrhea, negative plain abdominal and pelvic radiographs, and leukocytosis with neutrophilia?

Management of Abdominal Pain with Tenderness, Diarrhea, Negative Plain Imaging, and Leukocytosis with Neutrophilia

Obtain a contrast-enhanced CT scan of the abdomen and pelvis immediately, as plain radiographs have limited diagnostic value and this clinical presentation requires urgent evaluation for serious intra-abdominal pathology including appendicitis, diverticulitis, neutropenic enterocolitis, or Clostridioides difficile infection. 1, 2

Immediate Diagnostic Approach

Advanced Imaging is Essential

• Plain radiographs are inadequate for evaluating acute abdominal pain with these findings and should not delay definitive imaging 1, 2, 3
• CT abdomen and pelvis with IV contrast is the gold standard for patients presenting with abdominal pain, fever, and leukocytosis 4, 2, 4
• CT has superior diagnostic yield compared to plain films and can identify appendicitis, diverticulitis, colitis, perforation, abscess, bowel wall thickening, and mesenteric ischemia 1, 2, 5

Critical Laboratory Testing

Beyond the CBC showing leukocytosis and neutrophilia, obtain:

• Stool testing for C. difficile toxin - this is the most important microbiological test in patients with diarrhea and leukocytosis, especially if there is recent antibiotic exposure 6, 7, 8
• C-reactive protein (CRP) - elevated CRP >150-175 mg/L suggests complicated intra-abdominal pathology and higher mortality risk 9, 10
• Serum lactate - levels >2 mmol/L suggest bowel ischemia or severe sepsis 3
• Blood cultures (minimum two sets) if fever is present 7, 10
• Comprehensive metabolic panel to assess for electrolyte disturbances, renal impairment, and acidosis 6, 7

Key Differential Diagnoses to Consider

High-Priority Surgical Conditions

Appendicitis remains a leading concern with right lower quadrant pain, fever, and leukocytosis:

• CT with IV contrast has the highest diagnostic accuracy (rating 8-9 on ACR appropriateness criteria) 1, 4
• Marked leukocytosis (>15 × 10⁹/L) increases likelihood of complicated appendicitis 6

Diverticulitis should be suspected with left lower quadrant pain:

• CT abdomen/pelvis with contrast is rated 9 (usually appropriate) by ACR guidelines 1
• CRP >173 mg/L has 90.9% sensitivity and specificity for severe disease (Hinchey >Ib) 9

Life-Threatening Infectious Conditions

Clostridioides difficile infection (CDI) can present with minimal diarrhea but severe systemic toxicity:

• May present as "acute abdomen" with distention, pain, fever, and leukocytosis with absent or mild diarrhea 11
• Marked leukocytosis (>15 × 10⁹/L) and left shift (>20% bands) indicate severe colitis 6
• CT findings include colonic wall thickening, pericolonic fat stranding, and ascites 6
• Emergency colonoscopy is safe and diagnostic when CDI presents as acute abdomen, and can provide therapeutic decompression 11

Neutropenic enterocolitis if patient has cancer or recent chemotherapy:

• Occurs in 28% of neutropenic patients with abdominal pain 12
• CT/ultrasound shows bowel wall thickening >10 mm (especially cecum and right colon), which correlates with 60% mortality risk 10, 13
• Presents with fever, abdominal pain, diarrhea, and neutropenia (ANC <1000/μL) 10, 12, 13

Other Critical Considerations

Mesenteric ischemia:

• Severe pain out of proportion to examination findings is the hallmark 3
• Elevated lactate >2 mmol/L with abdominal pain warrants immediate CTA 3
• D-dimer >0.9 mg/L has 82% specificity for intestinal ischemia 3

Treatment Algorithm Based on CT Findings

If CT Shows Appendicitis or Diverticulitis with Complications

• Surgical consultation immediately 2
• Broad-spectrum IV antibiotics covering gram-negatives and anaerobes 2

If CT Shows Colitis Pattern

• Test for C. difficile using two-step approach (GDH antigen plus toxin EIA or NAAT) 7
• If CDI confirmed with severe disease (WBC >15 × 10⁹/L, creatinine >1.5× baseline, or signs of severe colitis): vancomycin 125 mg PO four times daily for 10 days 6
• If non-severe CDI: metronidazole 500 mg PO three times daily for 10 days 6
• Avoid antiperistaltic agents and opiates in suspected CDI 6

If Neutropenic Enterocolitis Suspected

• Broad-spectrum antibiotics per IDSA fever/neutropenia guidelines (anti-pseudomonal beta-lactam or carbapenem) 10
• Treatment is primarily non-operative with bowel rest and supportive care 10, 12
• Surgery reserved only for perforation or documented necrosis 10, 12
• Mortality is 30% at 30 days and 52% at 90 days in neutropenic patients with abdominal pain 12

If CT is Negative or Shows Non-Specific Findings

• Continue broad-spectrum antibiotics if sepsis signs present 2
• Consider inflammatory bowel disease, especially if pseudomembranes seen on colonoscopy without confirmed CDI 14
• Reevaluate for extra-abdominal sources (pneumonia, urinary tract infection) 2

Critical Pitfalls to Avoid

• Do not rely on plain radiographs - they become positive only after bowel infarction or perforation has occurred 3
• Do not assume normal lactate excludes serious pathology - it may be elevated from dehydration alone, but when combined with abdominal pain in an otherwise stable patient, consider early CT 3
• Do not miss CDI in patients with minimal diarrhea - it can present as acute abdomen with distention mimicking ileus, volvulus, or ischemia 11
• Lymphopenia (<1.4 × 10⁹/L) plus eosinopenia (<0.04 × 10⁹/L) with neutrophilia (>9.0 × 10⁹/L) has 94.9% specificity for severe infectious or surgical illness requiring intervention 15
• In neutropenic patients, fever, peritonitis, and leukocytosis may be mild or absent despite life-threatening pathology 10