Renal stones (module 2) Flashcards
epidemiology of stone disease
1-15% lifetime prevalence
peaks at 40-60 years, uncommon before age 20
Men > women, ratio 3:1
caucasian whites more commonly affected than asians
higher incidence in hot dry climates eg. northern Australia, Mediterranean countries, Central Europe.
higher BMI correlates with incidence of renal stones
occupation with exposure to excessive heat and dehydration eg. cooks and steel workers
cystine stones
> 5%
radiolucent and rare
form as a result of an inherited disorder, cystinuria, related to abnormal renal handing of dibasic amino acids
uric acid stones
approx. 12%
radiolucent
incidence increasing and may be associated with western diet
uric acid is a product of purine metabolism and its serum and urinary excretion in increased by diet high in animal protein.
magnesium ammonium phosphate
approx. 16%
also called infective stones, struvite, triple phosphate
usually radiopaque
these stones are caused by urease producing bacteria e.g. proteus
calcium stones
vast majority of stones are calcium stones
may be calcium oxalate (like 35%), calcium phosphate (like 7%) or mixed calcium phosphate and oxalate (like 30%)
usually can be seen on plain x-ray
about 10% of stones do not appear on traditional KUB-XR
symptoms and signs of renal stones
moderate to severe colicky pain
typically loin to groin pain
nausea/vomiting
haematuria
dysuria
oliguria
pyuria
fevers/rigors
what investigations should be conducted for someone with acute renal/ureteric colic
urine dipstick (microscopic haematuria is present >90%)
blood tests: FBC, U&Es, calcium, phosphate, uric acid
radiological tests: CT-KUB, IVU (intravenous urethrogram), RGPG (retrograde pyelogram), USS renal tracts
what should you rule out before diagnosing renal colic
leaking abdo inal aortic aneurysm, perforated peptic ulcer, peritonism
renal colic with obstruction and/or infection may lead to
urological emergency and can lead to death of kidney or patient
does the location of the stone change its likelihood of passing
stone at distal ureter is more likely to pass than stone at proximal ureter
how does size of the stone affect whether it will pass
stone <4mm: passes spontaneously
stone 4-7mm: might pass
stone >7mm: unlikely to pass
*this is only a guide, some very large stones may pass and some very small stones may require surgery
alpha blockers used to help pass stones
there has been some evidence to suggest that alpha blockers such as tamsulosin assist the spontaneous passage of stones
however, the largest randomised trail failed to show any benefit
staghorn calculus
a branched stone that fils the collecting system of the kidneys, filling renal calyces and pelvis
usually associated with infected urine, commonest organism is proteus vulgaris
as it grows it may destroy renal tissue by pressure and infection can cause renal damage
what to do when you encounter a patient with an obstructing ureteric stone
must be immediately referred to a urologist for further surgical management because infected and obstructed stones can cause sepsis and renal failure
the patient may require insertion of a JJ stent under GA, therefore they should be fasted
sometimes percutaneous nephrostomy (performed radiologically) is preferable to relieve infected, obstructive stones
management for non obstructing stones that are <7mm
analgesia and NSAIDs eg. panadeine forte, indomethacin
encourage increased PO fluid intake
IVH if dehydrated
urology outpatient follow-up with XR-KUB
dietary advice: reduce intake of animal protein, avoid highs oxalate containing foods
food that are high in oxalate
tea, coffee, chocolate rhubarb, spinach, okra, eggplant
indications for surgical management of a stone
infected obstruction (urgent)
persisting pain
persisting obstruction
any ureteric stone that fails to pass following a period of conservative management
ESWL - extracorporeal shockwave lithotripsy pros
day case
no general anaesthetic needed
least invasive
stones <2cm
ESWL cons
poor clearance rates
may require repeat procedures
contraindications for ESWL
pregnancy
distal obstruction
untreated bleeding
hypertension
UTI
cysteine stones
calcified AAA
renal failure
pacemaker
uteroscopy/lasertripsy pros
minimally invasive
excellent stone clearance <2cm
uteroscopy/lasertripsy cons
expensive
may require repeat precedes
may lead to open surgery if complications occur
possible complications in uteroscopy/lasertripsy
ureteric perforation
stricture
calculus obstruction
bleeding
pros of PCNL (percutaneous nephrolithotomy)
high stone clearance rate
renal/upper ureteric stones only
good for stones >2cm, including staghorns
cons of PCNL
invasive
possible complications of PCNL
bleeding
loss of kidney
ureteric obstruction
pneumothorax
PCNL stands for
percutaneous nephrolithotomy
pros of open/laparoscopic removal of stones
high stone clearance
cons of open/laparoscopic removal of stones
invasive
rarely used
which is the least invasive intervention for stones
ESWL
extracorporeal shockwave lithotripsy
which intervention is the mainstay of treatment
ureterenoscopy/lasertripsy
what are stents used for
stents are placed to relieve obstruction or following ureteric injury
how long can you leave a JJ stent in
can be left in situ for up to 6 months
what happens if a JJ stent is left in too long
can become grossly encrusted
side effects of JJ stents
usually well tolerated
mind intermittent haematuria and discomfort is common
some people find them intolerable/worse than the stone
prevelance of different stones
infected + obstructed stones =
sepsis + renal failure
percutenous nephrostomy
the placement of small, flexible tube through the skin into the kidney to drain the urine
pros and cons of different stone interventions
mainstay of management of stones in WA
flexible ureterenoscopy and laser
what advice should you not forget to give to patients
fluid and dietary advice because stones recur
