ClinCalc Pro — Kidney Stone Size vs Spontaneous Passage Rate
clincalcpro.com — decision support only; verify with current prescribing references and NICE.
Result
Spontaneous passage of a ureteric stone falls with size and with distance from the bladder, but these are separate observations, not points to add. On CT (Coll, AJR 2002): 1 mm 87 %, 2–4 mm 76 %, 5–7 mm 60 %, 7–9 mm 48 %, > 9 mm 25 %; proximal ureter 48 %, mid 60 %, distal 75 %, vesico-ureteric junction 79 %. Fever or infection with an obstructed kidney needs urgent decompression (stent or nephrostomy) whatever the size. Otherwise offer analgesia and observation (with medical expulsive therapy where appropriate) for small stones, and active removal (ureteroscopy or shockwave lithotripsy) for larger stones or failed passage, per the EAU urolithiasis guideline.
