A 60-year-old Caucasian female comes to the physician because of progressive shortness of breath for the past month. She has had a 13.6 kg (30 lb) weight loss during this period. She has a history of hypertension and hypothyroidism and takes metoprolol and levothyroxine. She has smoked two packs of cigarettes daily for 35 years. Her temperature is 36.7° C (98° F), blood pressure is 130/70 mmHg, pulse is 80/min, and respirations are 20/min. On examination, decreased breath sounds and dullness to percussion are noted on the right, middle and lower lobes of the lung. Her chest x-ray is shown below.
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Which of the following is the most appropriate next step in the management?
The clinical presentation and the chest x-ray of this patient is suggestive of pleural effusion with or without a lung mass. A pleural effusion is present when there is an excess quantity of fluid in the pleural space. When pleural effusion is suspected or diagnosed, the first step is to determine the cause of pleural effusion, and management starts with determining whether the fluid is transudate or exudate. Diagnostic thoracentesis is the preliminary investigation of choice in the management of pleural effusion, except in patients with classic signs and symptoms of congestive heart failure, where a trial of a diuretic is warranted.
Diagnostic thoracentesis is a bedside, minimally-invasive procedure that permits fluid to be rapidly sampled, visualized, examined microscopically, and quantified. Pleural fluid analysis provides decision-making information in 90% of cases. If a diagnostic thoracentesis shows exudative pleural fluid, further diagnostic investigations are indicated.
Malignant pleural effusion is very likely in this patient, who is a chronic smoker, presenting with weight loss and pleural effusion. A CT scan will most likely show a lung or mediastinal mass in this patient. Diagnostic thoracentesis would determine the type of pleural fluid (transudative fluid would rule out malignant effusion) and may also show malignant cells. Lung carcinoma, breast carcinoma, and lymphoma are the three tumors that cause approximately 75% of all malignant pleural effusions.
(Choices A, B, D, and E) are all useful in evaluating the cause of exudative pleural effusion; however, the first step in the management of pleural effusion is diagnostic thoracentesis to determine whether the etiology is transudative or exudative. Bronchoscopy is a close alternative in this case; however, this requires sedation and is considered to be a relatively invasive procedure. This will be the next step if the pleural fluid cytology is non-diagnostic and the patient has lung mass. If the pleural fluid cytology is positive for lung cancer, then the patient does not require a bronchoscopy.
(Choices F and G) Diuretics and echocardiography are indicated in patients with heart failure. In that case, patients present with fluid overload (weight gain), pedal edema, and, on exam, crackles are heard on both lung bases.
Educational Objective:
Undiagnosed pleural effusion is best evaluated with thoracentesis, except in patients with clear-cut evidence of congestive heart failure.
*Extremely high yield question for USMLE!!!