Renal Trauma, Obstruction and Stones Urethral Stricture: • Idiopathic • Congenital abnormality • Trauma/instrumentation • STI • Foreign body Prostate • Benign prostatic hyperplasia (BHP) • Prostate cancer • Prostate abscess • Previous surgery Bladder • Poor function • Bladder cancer  Bladder stones Kidney Stones Epidemiology • 1 in 10 males • 1 in 35 women • Highest rates in 40-60 year olds • 50% risk of recurrence in 5 years • BMI is a risk factor Pathogenesis • Supersaturated urine • Precipitation and crystal growth • Nucleation • Promotors:  Inhibitors: o Stasis o Urine composition o o Citrate Urea o Urine volume o Mg o Diet o Trace elements e.g. Zn o Metabolic diseases o UTIs o Medications Stone Composition • Calcium containing: o Most common is calcium oxalate (60%) o Hydroxyapatite (20%)  Non-Calcium containing: o Uric acid (7%) o Struvite (7%) Predisposing Risk Factors • Obesity • Metabolic acidosis • Type 1 renal tubular acidosis • Sarcoidosis • Chronic diarrhoea • Cystinuria • IBD • Hyperparathyroidism • Medullary sponge kidney • Adult PCKD • Medications o Vitamin C and D o Indinavir (anti-viral) o Frusemide o Acetazolamide (CAH inhibitor)  ↑H+ secretion  acidic urine o Bisphosphonates o Analgesia  NSAIDs Flomaxtra: dilates prostatic urethra in BPH Imaging  • KUB X-ray: however, not all stones are radio-opaque • KUB CT: all but indinavir stones due to crystal formation • Ultrasound: should detect all Ureteric Stent (J-J) • Stent is from bladder to renal pelvis • Stent allows urine to flow past blockage • Stent irritation symptoms o 70-80% o ↑Frequency of urination o Dysuria o Flank pain o Haematuria Uretero-Pyeloscopy and Laser Lithotripsy with Stone Retrieval • Ureteroscope into urethra  bladder  ureter • Basket instrument retrieves kidney stone Extracorporal Shockwave Lithotripsy (ESWL) • Shockwave is used to break up stones into smaller particles which can pass through the urinary tract more easily Percutaneous Nephrolithotomy (PCNL) • Percutaneous nephroscope used to gain direct access to kidney stone Open Surgery can also be used to remove stones in extreme cases Staghorn Calculi • Magnesium ammonium sulphate stones • Chronic infection • Urease-splitting organisms • Calculus occupies renal pelvis, major and even minor calices Stone Prevention • High fluid intake • Limited Na intake: ↑Na  ↑urinary Ca, ↑monosodium urate, ↓citrate • Limited animal protein o ↑Protein  ↓urine pH, ↓citrate, ↓Ca o ↑Purine load  ↑urinary uric acid • Weight loss • Recommended calcium intake Stone Investigations • Blood tests o EUC o Calcium o PTH o Uric acid • Stone analysis o Uric acid o Cysteine o Infection stone (struvite) o Pure calcium phosphate (RTA or elevated PTH) o Calcium oxalate or mixed calcium oxalate and calcium phosphate