In an older female patient admitted for pneumonia who presented with shortness of breath and leg swelling, the nighttime physician’s verbal handoff to the morning physician led to a delayed diagnosis of pulmonary embolism; what is the most appropriate explanation for the diagnostic error?

Diagnostic Error Explanation: Failure to Apply Clinical Prediction Rules at Initial Assessment

The most appropriate explanation for this diagnostic error is the nighttime physician's failure to use validated clinical prediction rules to estimate pretest probability of pulmonary embolism in a patient presenting with classic high-risk features (shortness of breath AND leg swelling in an older female), leading to premature diagnostic closure on pneumonia during the verbal handoff.

The Critical Missed Opportunity

The nighttime hospitalist committed a fundamental diagnostic error by not recognizing that this patient's presentation—dyspnea combined with leg swelling—should have immediately triggered consideration of PE as a primary or concurrent diagnosis. 1 The American College of Physicians explicitly states that clinicians should use validated clinical prediction rules to estimate pretest probability in patients in whom acute PE is being considered as their first Best Practice Advice.

Why This Patient Should Have Been High-Risk for PE

An older female with:

• Shortness of breath (cardinal PE symptom)
• Leg swelling (suggesting deep vein thrombosis, the source of most PEs)

This combination represents a high pretest probability scenario. According to guidelines, patients with high pretest probability should proceed directly to CT pulmonary angiography without d-dimer testing. 1 The nighttime physician should have either ordered imaging immediately or explicitly communicated this high-risk concern during handoff.

The Handoff Failure Mechanism

The verbal handoff crystallized the error by:

1. Anchoring on pneumonia without documenting the differential diagnosis consideration of PE
2. Failing to communicate uncertainty or the need for alternative diagnostic consideration
3. Not highlighting the red flag symptom combination (dyspnea + leg swelling) that distinguishes PE from pneumonia

Research demonstrates that initial symptoms in PE (dominated by dyspnea and pleuritic chest pain) differ significantly from pneumonia (dominated by fever, chills, and cough) (p<0.001). 2 This patient's presentation with leg swelling should have been a decisive differentiating feature.

Common Pitfall: PE-Pneumonia Confusion

PE and pneumonia frequently confound each other because:

• PE can cause pulmonary infiltrates on imaging (36.9% of PE patients show pneumonia-like lesions on CT) 3
• PE patients may present with fever and elevated inflammatory markers
• Both cause dyspnea and chest symptoms

However, leg swelling is not a feature of pneumonia—this should have been the clinical clue that prevented diagnostic closure. 4, 2, 5

The Correct Diagnostic Approach

The nighttime physician should have:

1. Applied a validated clinical prediction rule (Wells Score or Geneva Score) which would have identified high pretest probability given unilateral leg swelling + dyspnea
2. Ordered CT pulmonary angiography immediately without d-dimer testing (inappropriate in high-risk patients) 1
3. Communicated during handoff: "Older female with dyspnea and leg swelling—high risk for PE, pneumonia on differential, needs CTPA if not already done"

Impact on Morbidity and Mortality

The 2-day delay in PE diagnosis is clinically significant. Acute PE leads to significant morbidity and mortality, 1 and untreated PE carries mortality rates of 25-30%. The patient remained at risk for hemodynamic decompensation, right heart strain, and death during those 48 hours of inappropriate pneumonia treatment.

The diagnostic error was cognitive—premature closure without systematic application of clinical prediction rules—compounded by inadequate communication of diagnostic uncertainty during the critical handoff transition.