Diagnostic Error in Patients With Pulmonary Symptoms: More Challenging Cases

Alan Fein, MD; Joaquin E. Morante, MD; Aashir M. Shah, MBBS


December 19, 2017

A New Cough and Fever

A 72-year-old man with ischemic cardiomyopathy and heart failure with reduced ejection fraction presented to his physician with cough and shortness of breath associated with a low-grade fever for the past 3 weeks. He reported that he began having "flu-like symptoms" about 3 weeks ago, for which he was prescribed azithromycin. After the antibiotics, his symptoms improved but did not entirely abate. A chest x-ray showed clear lung fields but with bilateral moderate pleural effusions, left significantly greater than right (Figure 6).

Figure 6. First a chest x-ray (left) showing bilateral pleural effusion, and follow-up film (right) showing worsening left-sided pleural effusion.

His medical records noted a history of chronic bilateral pleural effusions that were deemed to be related to his heart (diagnostic sampling in the past revealed a transudative effusion).

On physical exam, he was found to have 1+ bilateral edema and decreased lung sounds bilaterally, more on the left side. The patient was told that his symptoms were secondary to his heart failure and pleural effusion, and he was prescribed a diuretic.

Three days after the visit, the patient presented to the emergency department with worsening shortness of breath and a high-grade fever. A chest x-ray revealed complete opacification of the left lung. Diagnostic thoracentesis was performed that showed a neutrophilic exudate with a pH of 6.9.

What was the diagnostic error?

Pleural Effusion

Pleural effusion has many etiologies and is usually classified as transudative or exudative on the basis of the protein, lactate dehydrogenase, glucose, and quantity of cells measured in the fluid. In general, all new or worsening pleural effusions should be sampled to determine the etiology. Two circumstances in which diagnostic sampling may not be required are:

  • A small pleural effusion and a secure clinical diagnosis (ie, viral pleurisy); or

  • Heart failure without atypical features—for example, bilateral pleural effusions with markedly different sizes, fever, and failure of effusions to resolve despite adequate diuresis. If atypical features are present, then sampling is recommended.

Complications of pneumonia that are associated with significant morbidity and mortality include parapneumonic effusions and empyema. Parapneumonic effusions fall into two categories:

  • Uncomplicated (ie, transudate with infection in the pleural space); or

  • Complicated (ie, exudate with bacterial invasion of the pleural space).

Empyema develops when there is bacterial infection of the pleural fluid, resulting in either pus or bacterial organisms on Gram stain.

Management of a parapneumonic effusion often requires both medical and surgical therapy, depending on characteristics of the sampled fluid, cultured organisms, and the presence or absence of loculations.

The patient in this case was diagnosed with an empyema that required a chest tube for drainage (Figure 7).

Figure 7. Empyema on a chest x-ray (left) and CT.

Cultures were positive for methicillin-sensitive Staphylococcus aureus. The patient received a course of appropriate antibiotics, with complete resolution of symptoms.


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