Workup for Watery Diarrhea with Left Lower Quadrant Tenderness
In this male with 6 days of watery diarrhea and left lower quadrant tenderness, obtain stool cultures for Salmonella, Shigella, Campylobacter, and Yersinia, assess hydration status, and consider abdominal CT imaging if diagnostic uncertainty persists after initial evaluation.
Initial Assessment and Diagnostic Testing
Stool Studies - First Priority
The 2017 IDSA guidelines provide clear direction for this presentation 1, 2:
- Obtain stool cultures for Salmonella, Shigella, Campylobacter, and Yersinia (strong recommendation)
- Test specifically for Yersinia enterocolitica given the left lower quadrant pain, as this pathogen causes mesenteric adenitis that can mimic appendicitis
- Do NOT empirically treat with antibiotics in immunocompetent patients with watery diarrhea without recent international travel (strong recommendation) 1
Critical History Elements
Ask specifically about:
- Recent antibiotic use (within 3 months) - if yes, test for C. difficile 2
- International travel within 3 days of symptom onset
- Exposure to raw/undercooked shellfish or brackish water (test for Vibrio if positive)
- Raw or undercooked pork products (Yersinia risk)
- Immunocompromised status
- Fever presence or absence
The Resolved Chest Pain Issue
This detail is clinically significant. Recent case reports document Campylobacter jejuni-associated myopericarditis presenting with chest pain and watery diarrhea 3, 4, 5. While rare (0.4% complication rate), this can be misdiagnosed as acute coronary syndrome. If the chest pain was pleuritic or retrosternal:
- Check troponin levels
- Obtain ECG
- Consider echocardiogram if troponin elevated
- This changes management if positive, as it would require colchicine and guideline-directed heart failure therapy 3
Imaging Considerations
When to Use CT
The 2022 ACP guidelines on left-sided colonic conditions recommend CT imaging when diagnostic uncertainty remains after history, physical exam, and labs 6. Use CT if:
- Concern for alternative diagnoses (diverticulitis, inflammatory bowel disease, malignancy)
- Severe or worsening abdominal pain
- Signs suggesting complicated disease
- Physical exam findings are equivocal
CT has very high sensitivity/specificity for diverticulitis but note that physical exam has only 30.91% accuracy and ultrasound 50.91% accuracy for left lower quadrant pathology 7.
When CT is NOT Needed
If this is straightforward infectious gastroenteritis with:
- Clear infectious prodrome
- Watery (not bloody) diarrhea
- No fever or systemic toxicity
- Improving or stable symptoms
- No peritoneal signs
Then stool studies alone are sufficient 1.
Hydration Management
Assess dehydration severity clinically (pulse, perfusion, mental status) 1:
- Mild-moderate dehydration: Oral rehydration solution (ORS) - reduced osmolarity formulation (strong recommendation)
- Severe dehydration or shock: IV lactated Ringer's or normal saline until hemodynamically stable, then transition to ORS
Common Pitfalls to Avoid
- Do not give empiric antibiotics for watery diarrhea without specific indications - this is a strong recommendation 1
- Do not use antimotility agents (loperamide) if fever is present or if inflammatory diarrhea suspected (risk of toxic megacolon) 1
- Do not miss C. difficile - must ask about recent antibiotic exposure 2
- Do not dismiss the chest pain history - Campylobacter myopericarditis is rare but increasingly recognized 3, 4, 5
- Do not order extensive stool panels without clear indications - one stool sample for the specific pathogens listed above is sufficient 2, 8
When Antibiotics ARE Indicated
Only treat empirically if 1:
- Immunocompromised host
- Clinical sepsis features
- Bloody diarrhea with fever
- Specific pathogen identified (Shigella, C. difficile)
If treatment needed: azithromycin or fluoroquinolone based on local resistance patterns 1, 8.