USMLE Step 2 Quiz: Pleural And Chest Wall Disorders

What this quiz covers

This quiz focuses on Pleural And Chest Wall Disorders, giving you a quick way to practice the rules, question types, and explanations that matter most for USMLE Step 2.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. Observation with high-flow oxygen
2. Discharge with follow-up in 24 hours
3. Insertion of a chest tube (correct answer)
4. Administration of intravenous furosemide

Explanation: A large (>3 cm) or symptomatic primary spontaneous pneumothorax requires intervention to re-expand the lung. The presence of significant symptoms (severe dyspnea, tachypnea) and the large size are clear indications for active intervention. The most definitive initial management is the insertion of a chest tube (thoracostomy). Needle aspiration is an alternative in some settings, but chest tube is the standard of care for a large, symptomatic pneumothorax.

Question 2

1. Observation and supplemental oxygen
2. Admission to the hospital and chest tube placement (correct answer)
3. Discharge with outpatient follow-up with pulmonology
4. Needle aspiration and discharge if successful

Explanation: This patient has a secondary spontaneous pneumothorax, which occurs in the setting of underlying lung disease (emphysema). These are more dangerous than primary pneumothoraces because patients have limited pulmonary reserve. Therefore, all patients with secondary spontaneous pneumothorax, regardless of size, should be admitted to the hospital and managed with chest tube placement to ensure lung re-expansion and prevent recurrence.

Question 3

1. Place a second, larger-bore chest tube
2. Instill intrapleural tPA and DNase via the chest tube (correct answer)
3. Increase the suction level on the current chest tube system
4. Remove the chest tube and begin a new course of antibiotics

Explanation: For a complicated, loculated pleural effusion or empyema that is not draining adequately with a chest tube alone, the next step is often to instill fibrinolytics (tissue plasminogen activator, tPA) and mucolytics (deoxyribonuclease, DNase) into the pleural space. This combination therapy helps to break down the fibrinous septations and viscous purulent material, facilitating drainage. If this fails, surgical intervention (VATS) is typically required.

Question 4

1. Triglycerides
2. Amylase (correct answer)
3. Adenosine deaminase
4. Creatinine

Explanation: The patient has acute pancreatitis, a common cause of pleural effusion, which is typically left-sided and exudative. Pancreatic enzymes can track into the pleural space, leading to a characteristically high pleural fluid amylase level (often higher than the serum level). High triglycerides suggest chylothorax, high adenosine deaminase suggests tuberculosis, and high creatinine suggests urinothorax.

Question 5

1. Passage of peritoneal fluid through diaphragmatic defects (correct answer)
2. Malignant infiltration of the pleura
3. Inflammation from an underlying pneumonia
4. Spontaneous bacterial infection of the pleural space

Explanation: This patient has hepatic hydrothorax, a complication of advanced cirrhosis with ascites. The mechanism involves the movement of ascitic fluid from the peritoneal cavity into the pleural space (most commonly the right side) through small defects in the diaphragm. The effusion is a transudate. While hypoalbuminemia contributes to fluid overload, the direct cause of the pleural effusion is this transdiaphragmatic passage.

Question 6

1. Increased capillary permeability
2. Decreased plasma oncotic pressure
3. Increased hydrostatic pressure (correct answer)
4. Impaired lymphatic drainage

Explanation: This patient's presentation is classic for decompensated congestive heart failure (CHF). In CHF, elevated left ventricular end-diastolic pressure leads to increased pressure in the pulmonary veins and capillaries. This increased hydrostatic pressure forces fluid out of the visceral pleural capillaries into the pleural space, resulting in a transudative pleural effusion.

Question 7

1. Protein level of 1.5 g/dL
2. Lactate dehydrogenase (LDH) level of 100 U/L
3. Pleural fluid to serum protein ratio > 0.5 (correct answer)
4. pH of 7.45

Explanation: The patient has pneumonia with a resultant parapneumonic effusion. Inflammation of the pleura leads to increased capillary permeability, causing leakage of protein and other large molecules into the pleural space. This results in an exudative effusion. According to Light's criteria, an exudate is defined by a pleural fluid/serum protein ratio > 0.5, a pleural fluid/serum LDH ratio > 0.6, or a pleural fluid LDH > 2/3 the upper limit of normal for serum LDH. The other options are characteristic of a transudative effusion.

Question 8

1. Exudative
2. Chylous
3. Hemorrhagic
4. Transudative (correct answer)

Explanation: The patient has nephrotic syndrome, characterized by massive proteinuria leading to hypoalbuminemia and decreased plasma oncotic pressure. This systemic condition causes fluid to shift into the interstitial spaces, leading to generalized edema, including pleural effusions. Effusions caused by imbalances in hydrostatic or oncotic pressures, as seen here, are transudative.

Question 9

1. pH 7.40, glucose 100 mg/dL, LDH 150 U/L
2. pH 7.35, glucose 80 mg/dL, lymphocyte predominance
3. pH 7.10, glucose 25 mg/dL, very high LDH (correct answer)
4. pH 7.50, glucose 120 mg/dL, low protein

Explanation: Pleural effusions associated with rheumatoid arthritis are exudative and have a characteristic biochemical profile due to intense pleural inflammation and impaired glucose transport into the pleural space. This profile includes a very low glucose level (often <30 mg/dL), a low pH (<7.20), and a very high LDH level. The other options describe transudative effusions or effusions more typical of other conditions like tuberculosis.

Question 10

1. Transudative
2. Exudative (correct answer)
3. Borderline
4. Chylous

Explanation: This effusion is exudative. Light's criteria are met if any of the following are true: 1) Pleural fluid protein/serum protein ratio > 0.5 (4.5/7.0 = 0.64); 2) Pleural fluid LDH/serum LDH ratio > 0.6 (400/250 = 1.6); 3) Pleural fluid LDH > 2/3 the upper limit of normal for serum LDH (400 > 2/3 * 200 ≈ 133). This fluid meets all three criteria, confirming it is an exudate, likely due to malignancy in this clinical context.

Question 11

1. Acute bacterial pneumonia
2. Malignancy
3. Tuberculosis (correct answer)
4. Congestive heart failure

Explanation: The clinical presentation (subacute constitutional symptoms, endemic area) combined with an exudative, lymphocytic-predominant pleural effusion is classic for tuberculous pleurisy. Malignancy can also cause a similar fluid profile but is less likely given the patient's age and specific symptoms. Acute bacterial pneumonia causes a neutrophilic effusion, and congestive heart failure causes a transudative effusion.

Question 12

1. Pleural fluid protein/serum protein ratio < 0.5
2. Grossly purulent fluid
3. Pleural fluid LDH > 2/3 the upper limit of normal for serum (correct answer)
4. Pleural fluid pH < 7.20

Explanation: Pleural effusions secondary to pulmonary embolism (PE) are typically exudative (in about 80% of cases) due to ischemia and inflammation of the pleura. Therefore, the fluid would be expected to meet at least one of Light's criteria for an exudate, such as an elevated LDH level. The effusion is usually small and may be bloody, but the other options are not characteristic. A protein ratio <0.5 suggests a transudate, purulent fluid suggests empyema, and a pH <7.20 suggests a complicated parapneumonic effusion.

Question 13

1. Spontaneous esophageal rupture
2. Acute pulmonary embolism
3. Primary spontaneous pneumothorax (correct answer)
4. Acute pericarditis

Explanation: This is the classic presentation of a primary spontaneous pneumothorax, which occurs without underlying lung disease. It is most common in tall, thin young men, and smoking is a major risk factor. The cause is the rupture of a subpleural apical bleb. The acute onset of unilateral pleuritic chest pain and dyspnea with diminished breath sounds on the affected side is highly suggestive.

Question 14

1. Acute exacerbation of COPD
2. Spontaneous bacterial pneumonia
3. Secondary spontaneous pneumothorax (correct answer)
4. Acute myocardial infarction

Explanation: Sudden clinical deterioration in a patient with known underlying lung disease like COPD should raise suspicion for a secondary spontaneous pneumothorax. This occurs due to the rupture of an underlying bleb or bulla. The unilateral physical findings of hyperresonance and absent breath sounds are classic for pneumothorax. While this is technically a type of COPD exacerbation, 'secondary spontaneous pneumothorax' is the more specific and actionable diagnosis.

Question 15

1. Obtain a stat portable chest x-ray
2. Perform endotracheal intubation and mechanical ventilation
3. Perform needle decompression of the right chest (correct answer)
4. Infuse 2 liters of normal saline

Explanation: This patient has the classic signs of a tension pneumothorax: hypotension (obstructive shock), tachycardia, jugular venous distention, tracheal deviation away from the affected side, and absent breath sounds. This is a clinical diagnosis and a life-threatening emergency. Immediate needle decompression in the second intercostal space at the midclavicular line is required to convert the tension pneumothorax to a simple pneumothorax, followed by chest tube placement. Waiting for an x-ray would be a fatal delay.

Question 16

1. Immediate chest tube insertion
2. Video-assisted thoracoscopic surgery (VATS) with pleurodesis
3. Observation with supplemental oxygen (correct answer)
4. Surgical consultation for emergent thoracotomy

Explanation: For a small (<2-3 cm) primary spontaneous pneumothorax in a clinically stable and asymptomatic or minimally symptomatic patient, conservative management is recommended. This involves observation and administration of supplemental oxygen. Oxygen increases the pressure gradient for nitrogen in the pleural space, accelerating the rate of pneumothorax resorption.

Question 17

1. Lung abscess
2. Empyema (correct answer)
3. Pulmonary embolism
4. Drug-resistant pneumonia

Explanation: Persistent fever despite appropriate antibiotic therapy for pneumonia, coupled with a worsening and loculated pleural effusion, is highly suggestive of the development of a complicated parapneumonic effusion or empyema. An empyema is a collection of pus in the pleural space that requires drainage for source control and resolution of the infection. A lung abscess is an infection within the lung parenchyma, while PE and drug resistance are less likely to cause a loculated effusion.

Question 18

1. Repeat therapeutic thoracentesis daily
2. Placement of a chest tube for drainage (correct answer)
3. Administration of intrapleural fibrinolytics
4. Surgical consultation for decortication

Explanation: The presence of grossly purulent fluid (pus) or a positive Gram stain from the pleural space defines an empyema. This is an absolute indication for complete drainage of the infected fluid. The standard initial procedure for achieving this is the placement of a chest tube (tube thoracostomy). Antibiotics alone are insufficient, and incomplete drainage leads to poor outcomes.

Question 19

1. Continue antibiotics and observe
2. Repeat thoracentesis in 24 hours
3. Insert a chest tube for drainage (correct answer)
4. Broaden antibiotic coverage to include anaerobic bacteria

Explanation: This patient has a complicated parapneumonic effusion. Even without a positive Gram stain or purulence, a pleural fluid pH < 7.20 or a glucose level < 60 mg/dL indicates a high level of inflammation and bacterial activity that will not resolve with antibiotics alone. These findings are indications for complete drainage of the pleural space, typically via a chest tube, to prevent the formation of a fibrous peel and trapped lung.

Question 20

1. Mycoplasma pneumoniae
2. Polymicrobial, including anaerobes (correct answer)
3. Legionella pneumophila
4. Influenza virus

Explanation: Empyemas that develop in the context of aspiration pneumonia are typically polymicrobial. The source of the infection is the oropharynx. In a patient with risk factors like poor dentition and dysphagia, the inoculum is likely to contain a mix of aerobic and anaerobic bacteria (e.g., Peptostreptococcus, Bacteroides, Fusobacterium). The other options are atypical pathogens or viruses that are uncommon causes of empyema.