American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the next step if repeat pleural fluid cytology is negative in a suspected malignant exudative effusion?

1. Observation without intervention

2. Thoracoscopy for further diagnosis

3. Immediate chemotherapy initiation

4. Needle aspiration for additional fluid analysis

The correct answer is: Thoracoscopy for further diagnosis

In cases of suspected malignant exudative pleural effusion where repeat pleural fluid cytology results are negative, thoracoscopy is considered the next appropriate step. This procedure allows for direct visualization of the pleural space and the opportunity to obtain biopsies of the pleura. This is crucial because the sensitivity of cytology for detecting malignancy can be limited. Thoracoscopy can enhance the likelihood of obtaining a definitive diagnosis by allowing the assessment of the pleural surfaces and targeted sampling of any suspicious areas. The other approaches mentioned may not provide the level of diagnostic clarity needed. Observation without intervention does not advance the diagnostic process and can delay necessary treatment if a malignancy is present. Immediate chemotherapy initiation without a confirmed diagnosis might expose the patient to potential harm and does not target the underlying issue. While needle aspiration for additional fluid analysis could be helpful in some circumstances, it might not yield more information than was obtained in the initial analyses, especially if cytology has already been performed multiple times. Therefore, thoracoscopy presents the most definitive option for diagnosis in this scenario.