• most originate in the kidneys
• 75% are Ca++ stones. Others include Struvite (magnesium ammonium phosphate and associated with chronic UTI's), uric acid and cystine.
• Mg and citrate are important inhibitors of stone formation
• distal stones can cause pain in testicles or labia

• Ix should include dipstick test, U&E's with other tests depending on complications of setting including fever
• degree of haematuria does not correlate with stone size or likelihood of passing
• non-contrast CT in adults and non-pregnant women or USS for others

• ≤2mm - average time to expulsion of 8/7
• 2–4mm - average time to expulsion of 12/7
• 4–6 mm - average time to expulsion of 22/7
• Spontaneous passage rate has been reported as a function of stone location with
  • 48% for stones in the proximal ureter
  • 60% for mid ureteral stones
  • 75% for distal stones
  • 79% for ureterovesical junction stones

• NSAIDs unless contra-indicated and should not be delayed for imaging
• opioids are 2nd choice
• α1 blockers eg Tamsulosin (400mcg daily) for 10/7 to facilitate passage of stone (relaxation of ureter and lower urinary tract)
  • Tamsulosin has been found to increase and hasten stone expulsion rates, decrease acute attacks by acting as a spasmolytic, reduces mean days to stone expulsion and decreases analgesic dose usage.
• may need IV hydration and anti-emetic if significant vomiting
• discharge from ED with stone clinic review if:
  • no evidence of sepsis
  • renal function not acutely impaired
  • stone is unilateral and contralateral kidney appears normal
  • pain well controlled
  • if stone >10mm definitive intervention within 4/52. Stones >7mm are less likely to spontaneously pass

References include:
Brit Assoc Urol: Mx of ureteric colic 2017
Nephrolithiasis overview 2020
Update in Renal stone Mx
Euro Soc Urology - Eval or renal stones 2020
Likelihood of spontaneous stone passage. Systematic review: Urol Int 2021
Stone passage and location. A Radiology J. 2001