Urinary Stones Flashcards
What is nephrolithiasis? [2]
List the common stone types in desc order? [4]
What is a staghorn stone? [1]
Microscopic mineral crystal formation in Loop of Henle, distal tubules, collecting duct
Calcium 80%
Triple Phosphate - 20% (infective)
Uric Acid - 10%
Cystine - 1%
Staghorn stones - one that involved the renal pelvis and calyces
What are the mechanisms leading to urinary stones? [4]
Explain underlying etiology [1]
- Elevated urinary solutes eg calcium, urate, oxalate, sodium
- Decreased levels of inhibitors eg Mg, citrate
- Low urinary volume
- Abnormally low/high urine pH
- Urine becomes super saturated with stone forming salts > stone formation
Describe the gender and age differences in epidemiology [2]
Men are 3x more likely.
Generally 20-50 yo peak age
Describe pain in nephrolithiasis [5]
Associated symptoms [4]
Explain why there is pain? [3]
Pain depends on location of stone:
- Loin or flank pain
- Ureteric colic radiating to groin
- Restlessness
- Testicular/vulvar pain
- Suprapubic, groin or penile pain (bladder stones)
Dysuria, voiding problems
~Pyrexia (urosepsis)
Recurrent UTIs
Haematuria
Colic is secondary to obstruction of collecting system
Increase in intraluminal pressure, stretches the nerve endings
Pain may also be due to local inflammatory mediators, oedema, hyperperistalsis and mucosal irritation
What blood tests would you run for a stone? [4]
- FBC - leukocytosis if UTI
- U&E, Creatinine - AKI
- Ca, urate, PTH
- Sepsis investigations
What other investigations? [4]
Urinalysis & culture 24 hr urine collection Non contrast spiral CT KUB Renal ultrasound, X-ray IV Urogram
What are the types of surgery for stones? [5]
Ureteroscopy: ureteroscope passed retrograde to ureter and into renal pelvis to insert stents which are normally left in for >4w
- Flexible Lithoclast
- Holmium Laser
ESWL (Extracorporeal Shock Wave Lithotripsy)
PCNL (Percutaneous Nephrolithotomy) access gained to renal collecting system percutaneously followed by intra-corporeal lithotripsy and removal of stone fragments
Open (Partial, simple or total nephrectomy)
Endoscopy
When would you use ESWL? [2]
What is ESWL? [2]
Cons [1]
Complications [2]
Ind: ESWL is the first line treatment for most upper tract stones. Except those >2cm.
Define: Shockwave generated external to pt and internally cavitation bubbles and mechanical stress > stone fragmentation
Cons: uncomfortable and requires analgesia during and after
Cx: solid organ injury due to shockwaves, ureteric obstruction due to fragmentation of larger stones
When would you use Endoscopic treatments? [5]
For bladder stones
Or higher if theres uncontrollable pain, severe obstruction, persistant haematuria or failed ESWL
When would you use PCNL? [2]
What is percutaneous nephrolithotomy [2]
Complex renal calculi
Staghorn caluli
Access gained renal collecting system percutaneously [1] followed by intra-corporeal lithotripsy and removal of stone fragments [1]
What are the types of open stone removal? [3]
Partial Nephrectomy - removes part of the kidney
Simple nephrectomy - removes the whole kidney
Total nephrectomy - removes the kidney, suprarenal gland and surrounding tissue
When do you do open surgery? [3]
IF a large stone –> Infection and non-function necessitates kidney removal
Or ESWL/PCNL aren’t available
Risk factors [7]
Dehydration Increase in stone forming salts Renal tubular acidosis Medullary sponge kidney Polycystic kidney disease Beryllium, cadmium exposure Drugs eg loop diuretics, steroids, acetazolamide, theophylline
State urine pH levels for each type of stone:
- Calcium phosphate
- Calcium oxalate
- Uric acid
- Struvite
- Cysteine
- Calcium phosphate: normal or alkaline
- Calcium oxalate: variable
- Uric acid: acid
- Struvite: alkaline
- Cysteine: normal
Immediate management [3]
IV fluids
IM diclofenac
Anti-emetics
What would indicate intervention? What would the initial intervention be? [2]
o Stones <5mm in maximal diameter and no obstruction: usually pass within 4w of symptom onset
o Obstruction:
- percutaneous nephrostomy tube
- insertion of ureteric catheters or ureteric stent (JJ “pigtail” stent) placement
Non-infective vs infective stone types
State 3 each
o Non-infective Stones Calcium Oxalate Calcium Phosphate Uric Acid o Infective stones: Magnesium ammonium phosphate Carbonate apatite Ammonium urate
Radiolucent vs radiopaque stones
State 3 each
Radiolucent:
- Uric acid stones
- Ammonium urate
- Xanthine
Radiopaque appearing white/light:
- Calcium oxalate
- Calcium phosphate
- Magnesium ammonium phosphate
Compare 3 methods of investigation: US, NCCT
US
Benefits: no radiation risk
Disadvantages: Difficult to visualise ureter and small stones
Non-contrast spiral CT KUB
Benefits: High specificity and sensitivity, ability to detect radiolucent stones (not detected from abdominal KUB x-ray)
Helpful to review the extent of obstruction (Showing hydronephrosis / hydroureter)
Disadvantages: relatively high radiation risk (Contraindicated in pregnant woman and child)
Prevention of stones
Calcium stones [4]
Oxalate stones [3]
- Calcium stones: high fluid intake, low animal protein, low salt diet, THIAZIDE diuretics (increase distal tubular calcium reabsorption)
- Oxalate stones: CHOLESTYRAMINE reduces urinary oxalate secretion, pyroxidine reduces urinary oxalate secretion
Prevention of stones
Uric acid stones [2]
Cysteine stones [2]
- Uric acid stones: ALLOPURINOL, urinary alkalisation e.g. oral bicarbonate
- Cysteine stones: PENICILLAMINE with PYROXIDINE B6 used to chelate
