C is the correct answer

This patient is presenting with signs and symptoms of pulmonary embolism (PE), including acute-onset chest pain and shortness of breath with associated tachycardia and mild hypoxia. Patients with PE can have a wide variety of presentations, from completely asymptomatic to sudden cardiovascular collapse. However, the most common symptoms include dyspnea and pleuritic chest pain. Although PE is typically thought to be associated with deep vein thrombosis, unilateral leg swelling is uncommon in patients with PE. The most common vital sign abnormality associated with PE is tachycardia (half of patients). Associated hypotension and hypoxia depend on the size and severity of the PE and its effect on the lung. However, only about half of patients will have an elevated respiratory rate, < 10% of patients will have hypotension, and only half of patients will develop hypoxia.

This huge variation in presentations and severity makes diagnosing and treating this condition challenging for emergency medicine clinicians. Different prediction tools can be used to determine the likelihood of PE. This specific patient not only has signs and symptoms that would suggest PE, but the clinician would be unable to clinically clear her of the diagnosis using the pulmonary embolism rule-out criteria (PERC) since she takes an oral contraceptive pill.

Once a PE is on the differential and further evaluation is required, the workup includes an ECG, chest radiograph, laboratory evaluation, including troponin and D-dimer testing, and CTA of the chest. Echocardiography is also helpful when there is concern for right ventricular strain. Once a PE is diagnosed, the pulmonary embolism severity index (PESI) can be used to determine the patient’s morbidity and mortality risks, helping the clinician formulate an appropriate treatment and disposition plan.

According to guidelines by the American Board of Emergency Medicine, patients with very low or low risk of morbidity and mortality from PE can be treated in the outpatient setting, and direct oral anticoagulants are preferred. Treatment at home is more convenient and less expensive than hospitalization, and the PESI can be used to risk-stratify patients. This tool uses vital sign abnormalities, age, sex, and medical history to determine the risk of complications. Using this patient’s age and elevated heart rate, she has a PESI score of 66 points, which puts her at low risk for complications from PE. Treatment for this patient, assuming no social issues limit her eligibility for outpatient care, would include a direct oral anticoagulant and close patient follow-up.

Using the PESI, we can calculate a patient’s risk for complications from PE. If this patient were slightly younger, she would have a very low (E) risk for complications associated with PE. However, if she had a history of heart failure, chronic lung disease, or cancer, her risk for complications from PE would increase to intermediate (B), high (A), or very high (D). Other abnormalities that increase a patient’s risk include a systolic blood pressure < 100 mm Hg, RR > 30/min, T < 36°C, altered mental status, and an oxygen saturation < 90%.

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