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Early-stage NSCLC — SCE Respiratory MCQ

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HardLung CancerEarly-stage NSCLCSCE Respiratory

Pleural infection is suspected and the decision to drain depends on pleural-fluid pH. Which sampling method best preserves an interpretable result?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: D — Collect in a heparinised blood-gas syringe without air exposure

Explanation lettering: E = shown as A · D = shown as B · B = shown as C · C = shown as D · A = shown as E

C is correct. Pleural pH should be collected anaerobically in a heparinised blood-gas syringe, with air expelled and prompt blood-gas analysis. Residual local anaesthetic falsely lowers pH, whereas air exposure can raise it. EDTA storage and dipsticks are insufficiently accurate for a threshold that determines chest-drain insertion.

Reference: https://thorax.bmj.com/content/78/Suppl_3/s43