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Renal pelvic calculus — MSRA MCQ

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ModerateNephrolithiasisRenal pelvic calculusMSRA

A 46-year-old man is reviewed in a stone clinic after 4 months of intermittent left flank discomfort. Low-dose non-contrast CT shows a 24 mm left renal pelvic calculus. Urine culture is negative, renal function is normal and there is no hydronephrosis. He has no bleeding disorder and wishes definitive treatment after discussion of the options. What is the most appropriate initial definitive management plan?

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

Reveal the answer and explanation

Correct answer: B — Offer percutaneous nephrolithotomy as initial definitive treatment

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

This is a renal, rather than ureteric, stone measuring more than 20 mm. NICE recommends percutaneous nephrolithotomy (PCNL) as the initial treatment for renal stones larger than 20 mm, including staghorn stones. The absence of infection, acute kidney injury and obstruction means urgent drainage is not required; however, the stone size makes elective definitive treatment appropriate. A and C are inappropriate because shockwave lithotripsy is the preferred initial option for renal stones smaller than 10 mm, not a 24 mm renal pelvic stone. Fragmentation with shockwave lithotripsy at this size is less likely to provide effective single-course clearance and is not the NICE first-line recommendation. B is plausible because flexible ureteroscopy is used for renal stones, but for stones larger than 20 mm it is considered when PCNL is not an option. D incorrectly places PCNL after ureteroscopic failure; that sequencing applies to some smaller renal stones, whereas PCNL is the recommended initial modality above the 20 mm threshold.

Reference: NICE NG118: Renal and ureteric stones: assessment and management — Recommendations (Published 2019; updated May 2026) — https://www.nice.org.uk/guidance/ng118/chapter/Recommendations