Is a chest CT angiography indicated for PE in a patient with bilateral DVTs and no SOB?

CT Angiography Is Not Indicated for PE Evaluation in a 67-Year-Old Patient with Bilateral DVTs Who Denies Shortness of Breath

In a 67-year-old patient with known bilateral DVTs who denies shortness of breath, CT pulmonary angiography is not indicated to look for pulmonary embolism (PE).

Rationale for Not Performing CTPA

Clinical Presentation Assessment

• According to the British Thoracic Society guidelines, most patients with PE are breathless and/or tachypneic (>20/min); in the absence of these symptoms, PE is less likely 1
• The absence of shortness of breath is particularly significant, as dyspnea is present in 82-85% of patients with confirmed PE 1
• Clinical probability assessment is a crucial first step in PE evaluation, and the absence of respiratory symptoms significantly lowers clinical probability

Risk-Benefit Analysis

• CTPA exposes patients to:
  • Ionizing radiation
  • Intravenous contrast with potential for contrast-induced nephropathy
  • Unnecessary healthcare costs
• In a patient with already diagnosed bilateral DVTs, the treatment plan (anticoagulation) would likely remain the same regardless of PE diagnosis

Diagnostic Algorithm for PE Suspicion

1. Clinical Probability Assessment:

   • The patient has a major risk factor (bilateral DVTs) but lacks key PE symptoms
   • This places them in an intermediate clinical probability category 1

2. Management Approach:

   • For patients with diagnosed DVT, anticoagulation is already indicated
   • The absence of respiratory symptoms suggests stable condition without massive PE
   • Current guidelines support treating the DVT without additional imaging for PE in asymptomatic patients

3. When CTPA Would Be Indicated:

   • Development of shortness of breath
   • Tachypnea (respiratory rate >20/min)
   • Chest pain (particularly pleuritic)
   • Hemoptysis
   • Signs of hemodynamic instability

Alternative Approaches

• If there are concerns about PE despite the absence of shortness of breath:
  • Monitor for development of respiratory symptoms
  • Consider clinical assessment tools (Wells score, Geneva score)
  • Assess vital signs for tachycardia, tachypnea, or hypoxemia

Common Pitfalls to Avoid

1. Overutilization of CTPA:

   • Studies show CTPA confirms PE in only 14.9-38% of suspected cases 2, 3
   • Indiscriminate use results in unnecessary radiation and contrast exposure 4

2. Ignoring Clinical Presentation:

   • The absence of shortness of breath significantly reduces PE likelihood
   • The British Thoracic Society specifically notes that in the absence of breathlessness/tachypnea, other symptoms like pleuritic chest pain are usually due to another cause 1

3. Redundant Testing:

   • In a patient with confirmed bilateral DVTs already requiring anticoagulation, PE diagnosis would rarely change management unless massive PE is suspected

In conclusion, for this 67-year-old patient with known bilateral DVTs who denies shortness of breath, the best approach is to treat the DVTs with appropriate anticoagulation and monitor for development of respiratory symptoms, rather than proceeding directly to CTPA.