The Virtual Hospital: ElectricPE: The Diagnosis of Pulmonary Embolism: No Apparent Risk Factors

ElectricPE: The Diagnosis of Pulmonary Embolism: Case Study 3

No Apparent Risk Factors

Jeffrey R. Galvin, M.D. and James J. Choi, B.S.
Peer Review Status: Internally Reviewed

This case is a 34 year old female, known alcohol abuser, who presented with a 1 week history of fatigue, myalgias and a low grade fever. This was accompanied by right sided pleuritic chest pain, cough and hemoptysis. Although she had a 30 pack year history of smoking, she had no definable risk factors for pulmonary embolus. Her blood gases on admission showed a mild respiratory alkalosis and hypoxemia on room air. (PH of 7.45, Pco2 of 34 and a Po2 of 78)

Linear densities were present in the posterior aspect of the right lower lobe consistent with atelectasis.

The perfusion scan shows multiple segmental and subsegmental defects in both lower lung fields. The largest area of perfusion abnormality in the right lower lobe matches the areas of atelectasis on the chest radiograph.

The ventilation scan demonstrates a minimal area of Xenon retention in the right lower lobe.

This V/Q scan was read as indeterminate because of the matched abnormalities on the chest radiograph and the perfusion scan in the right lower lobe. It is interesting to note once again that the ventilation scan does not pick up the area of atelectasis demonstrating its poor spatial resolution relative to the perfusion scan. This was noted by Eugene Robin in the 1977 Annals of Internal Medicine.

Duplex Doppler exam of Both legs:
The major deep leg veins were patent and easily compressible. There was normal blood flow augmentation by Doppler exam.

The angiogram demonstrates a filling defect in a segmental right lower lobe artery.

Case Assessment
This is a 34 year old woman who presents with symptoms that are highly suggestive of pulmonary embolus but no clear underlying cause.

1. Pulmonary angiography is an appropriate procedure because the indeterminate ventilation/perfusion scan leaves the patient and the physician without a clear course of therapy. The diagnosis of pulmonary embolus in an otherwise healthy, active individual will have a significant effect on how that person conducts the rest of their life. It is therefore, important to make a definitive diagnosis. The need for such a high degree of diagnostic certainty may become less significant in patients with other life limiting problems such as widely spread malignancy.

2. This case once again points up the relatively poor spatial resolution of the Xenon ventilation scan when dealing with small perfusion defects.

3. The chest radiograph is often abnormal in patients with pulmonary embolus although the findings are often non-specific.

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