How do you diagnose pulmonary embolism (PE) in a patient with end-stage renal disease (ESRD) on dialysis?

Diagnosing Pulmonary Embolism in Dialysis Patients

In dialysis patients with suspected PE, proceed directly to CT pulmonary angiography (CTPA) as the primary diagnostic test, bypassing D-dimer testing, which has limited utility in this population due to chronically elevated levels from comorbidities. 1

Key Diagnostic Approach

Why D-dimer Testing is Unreliable in Dialysis Patients

• D-dimer measurement has limited usefulness in hospitalized patients with multiple comorbidities (infection, inflammation, chronic kidney disease), as these conditions yield persistently elevated D-dimer levels regardless of PE presence 1
• In hospitalized patients with suspected PE, D-dimer testing allows PE to be ruled out in less than 10% of cases, compared to 36% in emergency department patients 1
• Dialysis patients have chronically elevated D-dimer levels, making this test essentially non-diagnostic in this population 1

Recommended Diagnostic Algorithm for Dialysis Patients

Step 1: Clinical Probability Assessment

• Use clinical gestalt or a validated prediction tool (Wells criteria or Geneva score) to assess pretest probability 1
• However, recognize that most dialysis patients will have intermediate-to-high clinical probability due to their multiple comorbidities 1

Step 2: Proceed Directly to Imaging

• For hemodynamically stable dialysis patients: Order CTPA as the first-line imaging test 1
• For hemodynamically unstable patients (shock or hypotension): Perform bedside echocardiography immediately to assess for right ventricular dysfunction and acute pulmonary hypertension 1

Step 3: Alternative Imaging if CTPA Contraindicated

• If contrast is contraindicated due to residual renal function concerns or recent contrast exposure: Consider ventilation-perfusion (V/Q) lung scanning 1
• Consider lower extremity compression ultrasonography (CUS) as finding a proximal DVT in a patient with suspected PE is sufficient to warrant anticoagulation without further pulmonary imaging 1, 2

Special Considerations for Dialysis Patients

Contrast Administration Concerns

• In anuric dialysis patients (no residual renal function), contrast-induced nephropathy is not a concern, making CTPA the preferred diagnostic modality 1
• For patients with residual renal function, weigh the risk of contrast exposure against the mortality risk of untreated PE, which is significantly elevated in ESRD patients 3

Lower Extremity Ultrasound as Adjunct

• CUS shows DVT in 30-50% of patients with PE and has >90% sensitivity for symptomatic proximal DVT 1, 2
• Finding a proximal DVT eliminates the need for pulmonary imaging and justifies immediate anticoagulation 1, 2
• This approach is particularly valuable when CTPA is contraindicated or unavailable 2

Hemodynamically Unstable Dialysis Patients

• Bedside transthoracic echocardiography is the most useful initial test, showing right ventricular dysfunction and acute pulmonary hypertension if PE is present 1
• In highly unstable patients, echocardiographic evidence of RV dysfunction may be sufficient to initiate emergency reperfusion therapy without waiting for CTPA 1
• Echocardiography also helps differentiate other causes of shock (tamponade, acute valvular dysfunction, cardiogenic shock, aortic dissection) 1

Critical Pitfalls to Avoid

Do Not Rely on D-dimer Testing

• The single most important pitfall is ordering D-dimer tests in dialysis patients, as chronic inflammation, infection, and ESRD itself cause persistently elevated levels 1
• A negative D-dimer cannot safely exclude PE in this population due to reduced specificity 1

Recognize Increased Mortality Risk

• Dialysis patients with PE have significantly higher mortality rates (6.8% in-hospital mortality for ESRD patients versus 2.7% for those with normal kidney function) 3
• This elevated mortality risk mandates aggressive diagnostic evaluation and should lower your threshold for imaging 3

Vascular Access Procedures as PE Risk

• Dialysis access declotting and angioplasty procedures can precipitate PE, including cholesterol crystal embolization 4
• Maintain high clinical suspicion for PE following these interventions, particularly in patients with multiple comorbidities 4

Practical Algorithm Summary

1. Assess clinical probability using Wells or Geneva criteria 1
2. Skip D-dimer testing entirely in dialysis patients 1
3. If hemodynamically stable: Order CTPA immediately 1
4. If hemodynamically unstable: Perform bedside echocardiography first 1
5. If CTPA contraindicated: Use V/Q scan or lower extremity ultrasound 1, 2
6. If proximal DVT found on ultrasound: Initiate anticoagulation without further testing 1, 2