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Renal Tract Calculi . Alex Papachristos. Overview. Background Pathophysiology Epidemiology Presentation Investigation Management. Background. 1% of hospital admission are due to acute renal colic Excruciating pain > broken bones, childbirth, gunshot. Pathophysiology.
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Renal Tract Calculi Alex Papachristos
Overview • Background • Pathophysiology • Epidemiology • Presentation • Investigation • Management
Background • 1% of hospital admission are due to acute renal colic • Excruciating pain > broken bones, childbirth, gunshot
Pathophysiology • supersaturation of urine by stone-forming constituents (calcium, oxalate, uric acid) • Crystals / foreign bodies act as nidi – ions from supersaturated urine can form microscopic crystalline structures
Stone composition • 80% calcium containing (oxalate/phosphate) • Struvite (10-15%) • Uric acid (5-10%) • Rare – familial (homocysteinuria), Indinavir
Epidemiology • Lifetime prevalence – 12% for men, and 7% for women (US data) • Rates are doubled if there is a FMH • Peak incidence 35-45 years • Initial stone attack after 50yrs uncommon • Male:Female ratio: 3:1 • More common in Anglo-Saxons and Asians than native Americans, African
Risk factors • Low fluid intake • Western diet • Supplemental calcium
Presentation • Symptoms • Pain • Nausea and Vomiting • Haematuria • Fever
Diagnosis • Xray KUB • CT KUB (non-contrast) • Xray IVP
Management • Initial Mx: • Pain relief • Hydration • Basic bloods • Is there an indication for urgent intervention?
Indications for Intervention • Infected obstructed kidney • Impaired renal function due to obstruction • Solitary kidney • Uncontrolled pain
Emergency Intervention • Immediate aim is relieving obstruction • Double-J stent insertion • Ureteroscopic stone extraction (if no active infection) • Nephrostomy
Will the stone pass? • Size of stone is inversely proportional to its chance of passing spontaneously • Rule of thumb: • 1mm stone - 90% chance of passing • 4mm stone - 60% chance • 8mm stone - 20% chance
Watchful Waiting • Stones that have not passed in two month are unlikely to do so • Permanent damage to kidney occurs after ~4 weeks • Can try an alpha-1 blocker - smooth muscle relaxant
Treatment options • Watchful waiting • ESWL • Ureteroscopic stone extraction • Percutaneous nephrolithotomy
Long-term Management • High fluid intake is most important • Stone analysis - alkalanise urine if uric acid stone • Low salt, high fibre diet
Bladder Calculi • Most common in men aged > 50 with bladder outlet obstruction • Stasis of urine leads to stone formation