Question

A chest X-ray shows bilateral lung infiltrates suggestive of diffuse parenchymal lung disease. The next most appropriate investigation is:

• A. Sputum examination
• B. CT scan (HRCT)
• C. Bronchoscopy
• D. Empirical antibiotics

Hint:

For diffuse bilateral infiltrates, HRCT is the next step to characterise the pattern.

Answer 1

The Correct Option is B

Step 1: Bilateral diffuse infiltrates on a plain chest film raise the suspicion of interstitial (diffuse parenchymal) lung disease. The plain film cannot characterise the pattern in enough detail.

Step 2: The next step is high-resolution computed tomography (HRCT) of the chest. HRCT is obtained in nearly all patients with diffuse pulmonary parenchymal disease because it defines the distribution and pattern (reticular, nodular, ground-glass, honeycombing) and often narrows the differential.

Step 3: Sputum examination and antibiotics target infection, which is not the leading concern in a diffuse interstitial pattern. Bronchoscopy and biopsy may follow later, but only after HRCT has localised and characterised the disease.

Step 4: Hence HRCT is the logical immediate next investigation after the abnormal chest X-ray.