Renal stones Flashcards
Epidemiology
M>F
Prevalence= 20% in western society
Ethnicity= white
Risk factors
- Intrinsic
- Extrinsic
Intrisic
- Age: 20-50
- Sex (M>F)
- Race (white)
- Genetics: 25% have family history (i.e cysteinura, xanthine, hypercalciuric)
Extrinsic
- Occupation
- Geography
- Diet
Types of stones and prevalence
Most common= calcium oxalate (60%)
Calcium phosphate (20%)
10%- Urate
8%- Strivite
1%- Cysteine
Aetiology
Based on different states of urine saturation
Crystallisation occurs when concentration is high and inhibitors of crystal growth are not effective
Metabolic
- Hyperparathyroidism
- Hypercalciuria
- Sarcoid
- Too much vit D
Familial
- Cystienuria
- Purine metabolic error
- Xanthinuria
Infection
Impaired drainage
Inhibitors of stone formation
citrate
- Phytate
- Magnesium
Presentation of renal stones
Renal colic
- Loin to groin radiation
- Difficult to get comfortable
Haematuria
UTI
Investigations
U+Es
- Cr, urea, K+
Ca2+
PTH
- Causing hypercalcaemia
eGFR
Urine
- Infection
- pH
- Culture
Stone analysis if stone has been passed
Imaging
- XR KUB
- Non contrast CT (gold standard)
- Isotope renograph (long term)
Management options for stones
Conservative
- Small stones that are non-obstruction, wait for it to pass
Medical
- To relax ureter
- Medical expulsive therapy
- Chemolysis (uric acid stones)
Shock lithotripsy (ESWL)
- Extracorporeal shock wave lithotripsy
- Targeted on calculus
Ureteroscopy
- Uterosc
PCNL (percutaneous nephrolithotomy)
- Better for bigger stones (in renal pelvis/ calyces)
Lap/ open surgery rarely used
- Large staghorn or complex stones
Non-contrast CT
- advantages
100% sensitivity
and very high specificity
Helps to identify location of stones
Idea of pathology
Stone fragility
Non-contrast CT
- disadvantages
Radiation dose
- But lower dose can be used
Non-dynamic due to dye not being used
Obstruction is implied not directly known
- Perinephric stranding
- Hydronephrosis
- Hydroureter
Conservative treatment
- Stone size
- Stone position
Stone size
- <4mm= 80% of passing
Stone position
- The more proximal, the harder it is to pass
If at VUJ, <5mm= 95% spontaneous passage
Indications for non-conservative intervention
Uncontrolled persistent pain
Infection
Deteriorating rena; function
Single kidney
Stone is not moving
Shock wave lithotripsy
- Process
- Mechanism
Shock waves focused on stone. Different wave types
- Electrohydraullic
- Electromagnetic etc
Waves fragments stones
Requires 2-3 sessions
Mechanism
- Positive then negative pressure creates cracks in the stones
Shock wave lithotripsy
- Success rates
Renal pelvis stones most successful (86-89%)
Lower pole= lowest success rate
Complications from ESWL
Steinstrasse
- Fragments form on top of each other
Residual fragment re-growth
- fragments can start to regrow
Fragment colic
Sepsis
Maco haemuturia- common
Haematoma
Ureteroscopy
Scope passed from urethra–> bladder–> ureter
- Uses laser to fragment scope
- Cannot look into kidney
Flexible scope
- allows kidney calyces to be seen
Ureteroscopy
- Success rate
More successful than ESWL for mid and distal ureter
Similar success rate for proximal ureter with ESWL
PCNL indications
Large stones (>2cm)
Complex stones
- Multiple stones
- Lower pole
- Abnormal anatomy
- Calyx diverticulum
- Difficult access
- Calcified stents
Indications for lap and open surgery
Lap
- If ESWL or Scope surgery has failed
- Very large stones in ureter
- Reconstructive also being done
Open
- Very rare
Prevention of stones
Increase fluid intake
- Dilutes urine
- 2.5L
Lose weight
Good diet
- High in citrate
Low salt
- <6g/day
- less animal protein
Avoid XS sugar
Urine alkalization
Thiazide
Calcium stones
Most common type
- Oxalate the most common
- Phosphate is less common
Struvite stones
- Composition, shape
- Cause
Mg, ammonium, calcium phosphate
- 2nd most common type
- Occurs due to chronic UTI
Staghorn calculi
Uric acid stones
Radiolucent stones,
high levels of uric acid
- 5% of all stones (3rd most common)
Acute management of renal colic
- Analgesia
- diclofenac PR - Antiemetic
- Metoclopramide - IV fluids
If stone <0.5cm, could wait to pass.
If emergency/ larger
- Nephrostomy/ stent insertion
