What is the next step in the workup for an 80-year-old female (F) with a complex past medical history (PMHx) including Chronic Obstructive Pulmonary Disease (COPD) on oxygen (O2), atrial fibrillation (afib), Chronic Kidney Disease (CKD), and cardiomyopathy with an ejection fraction (EF) of 35%, presenting to the outpatient Gastroenterology (GI) clinic for follow-up after a hospitalization for diarrhea and abdominal pain secondary to Enteropathogenic Escherichia coli (EPEC) infection?

Next Steps in Outpatient GI Workup for 80-Year-Old Female with EPEC-Related Diarrhea

The next step in workup for this 80-year-old female with complex medical history following hospitalization for EPEC-related diarrhea should be stool studies including fecal calprotectin, stool cultures, and C. difficile testing to rule out persistent or recurrent infection. 1

Initial Assessment

Laboratory Testing

• Complete blood count (CBC) to assess for ongoing inflammation
• Comprehensive metabolic panel (CMP) to evaluate:
  • Electrolyte abnormalities from diarrhea
  • Renal function (especially important given her CKD)
  • Liver function tests (baseline and to monitor for medication effects)
• Fecal calprotectin to differentiate between inflammatory and functional causes 1
• Stool studies:
  • Repeat stool culture to confirm clearance of EPEC
  • C. difficile toxin testing (especially important given recent hospitalization)
  • Ova and parasites if diarrhea persists

Symptom Assessment

• Document precise characteristics of current diarrhea:
  • Frequency, consistency, volume
  • Presence of blood or mucus
  • Associated symptoms (abdominal pain, fever, weight loss)
  • Duration since hospital discharge
  • Response to any treatments tried

Risk Stratification

This patient is at high risk for complications due to:

1. Advanced age (80 years)
2. Multiple comorbidities (COPD on O2, atrial fibrillation, CKD, cardiomyopathy with EF 35%)
3. Recent hospitalization
4. Risk of dehydration affecting cardiac and renal function

Diagnostic Considerations

If Diarrhea Has Resolved

• Baseline laboratory tests to ensure resolution of inflammation
• Consider colonoscopy only if:
  • Age >50 with no recent colonoscopy (for cancer screening)
  • Persistent symptoms despite negative stool studies 1

If Diarrhea Persists

• Fecal calprotectin >50 mg/g suggests inflammatory bowel disease or ongoing infection 1
• Flexible sigmoidoscopy or colonoscopy with biopsies to evaluate for:
  • Microscopic colitis (common in elderly)
  • Inflammatory bowel disease
  • Ischemic colitis (given cardiac history)
  • C. difficile colitis if toxin testing is positive

Management Considerations

Immediate Management

• Assess hydration status and need for IV fluids
• Monitor electrolytes closely, especially in the setting of CKD
• Evaluate medication list for potential contributors to diarrhea

Follow-up Planning

• Schedule follow-up within 2-4 weeks to assess symptom resolution
• Monitor weight and vital signs
• Assess nutritional status and need for supplementation

Special Considerations for This Patient

• Cardiac function monitoring is essential as diarrhea and dehydration can worsen heart failure
• Medication adjustments may be needed if diarrhea affects absorption
• Oxygen requirements may increase with dehydration or infection
• Anticoagulation management for atrial fibrillation may need adjustment if bleeding is present

Common Pitfalls to Avoid

1. Attributing persistent symptoms solely to prior EPEC without ruling out new or concurrent infections
2. Overlooking C. difficile infection, which is common after hospitalization
3. Missing medication-related causes of diarrhea
4. Failing to assess the impact of diarrhea on the patient's complex comorbidities
5. Delaying endoscopic evaluation in patients with persistent symptoms 1

This structured approach ensures comprehensive evaluation while prioritizing the most likely diagnoses in this high-risk elderly patient with multiple comorbidities recovering from EPEC infection.