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BJUI > Urolithiasis > Flashcards

Urolithiasis Flashcards

1
Q

staghorn stones are most frequently composed

A

magnesium ammonium phosphate (struvite) and/or calcium carbonate apatite and rarely due to calcium oxalate or phosphate stones.

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2
Q

Urea splitting organisms

A 
Proteus
    Pseudomonas
    Klebsiella
    Staphylococcus
    Mycoplasma.
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3
Q

Treatment options for Staghorn

A 
Open pyelolithotomy
open anatrophic pyelolithotomy
ESWL
flexible ureteroscopy 
PCNL (+ESWL,) or (PCNL+ESWL+PCNL)
Endoscopic combined intrarenal surgeries  (nephroscope + ureteroscope)
Medical dissolution with RENACIDIN
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4
Q

give 3 stone scoring systems created with the aim of determining complications and stone-free rates

A

Guy’s stone score
S.T.O.N.E nephrolithometry system
CROES nomogram.

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5
Q

GUYS STONE SCORE

A

grade 1 - single stone in mid/lower pole or single stone in the pelvis with simple anatomy
grade 2 - single stone in upper pole or multiple stones in a patient with simple anatomy or a single stone in a patient with abnormal anatomy
grade 3 - multiple stones in a patient with abnormal anatomy or stones in a calyceal diverticulum or partial staghorn calculu
grade 4 - staghorn calculus or any stone in a patient with spina bifida or spinal injury

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6
Q

Proper diet for urolithiasis (diet)

A

(+)promote low-salt, low-protein diet combined with normal calcium intake,high intakes of fresh fruit, fibre from wholegrain cereals and magnesium were associated with decreased stone formation risk
(-) high oxalate, modern high-protein/low-carbohydrate dietary fads, fructose consumption

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7
Q

Physical properties of SWL

A

Shock waves
Spallation
Cavitation

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8
Q

DEFINE CAVITATION

A

occurs as a shock wave passes through fluid, creating microscopic air bubbles. These bubbles coalesce at the stone’s surface and as the next shock wave arrives the bubbles collapse and release microjets of energy against the surface of the stone

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9
Q

DEFINE SPALLATION

A

The wave of energy passes uninterrupted through media of similar density such as water. However, when the wave meets an object of differing density, like a stone, there is increased resistance to energy transmission, termed acoustic impedance.

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10
Q

Components of a shockwave lithotripter

A
  1. SHOCK WAVE
  2. FOCUSING DEVICE
  3. COUPLING MEDIUM’
  4. LOCALIZATION MEDIUM
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11
Q

etiology of New-onset htn from SWL

A

Shock wave injury to surrounding normal parenchyma results in vasoconstriction and ischaemia, while shear stress may also induce vascular injury–>Vascular damage and ischaemia results in an inflammatory cascade and free radical formation

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12
Q

Incidence of STreinstrasse in SWL for stones less than 2 cm

A

The incidence of steinstrasse depends on the size of the treated stone, but ranges are reported from 2-6% in stones less than 2cm

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13
Q

Patient Selection for Shockwave therapy –> composition, HU and size, SSD

A

Composition -> not cystine stones they are able to deform and absorb shock wave energy, Brushite and calcium oxalate are harder making them resistant to cavitation and spallation
HU - 900, 50% less likely to be Stone free
Size- <1 cm stones approaches 80% SFR, 2 CM do not attempt
Skin-to-stone distance <10 cm

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14
Q

LIP Variable on stone-free rates fir SWL

A

LIP angle >70%
IW >5mm
IL <3cm

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15
Q

Adjunctive measures for SWL

A

Success, defined as the patient being stone-free or having fragments smaller than 3mm on ultrasound, was higher at three months in the tamsulosin group

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16
Q

Conservative management of ureteric calculi, % of passage by size

A

4 mm: 78-95%
5 mm: 68%
5-10mm: 47%

17
Q

when to use MET for ureteric stones

A

<10 mm

no evidence of sepsis,normal crea, adequate pain cntrol

18
Q

when to use pre-SWL stenting?

A

for solitary kidney,obstruction,sepsis,uncontrollable pain otherwise stents impedes stone passage and does not prevent Steinstrasse

19
Q

Surgical Management of stone for pregnant patients and what semester to avoid to do procedure

A

Failing conservative management, diversion via ureteric stenting or nephrostomy drainage is recommended.
URS with laser lithotripsy has been deemed safe during pregnancy.
When possible, deferring URS beyond the first trimester is preferred to avoid potential teratogenic effects of anaesthesia

20
Q

medications linked with stone formation

A

Carbonic anhydrase inhibitors (such as topiramate and zonisamide) cause a renal acidification defect similar to RTA and increase the risk of calcium phosphate stones.
Excessive use of supplements such as calcium or vitamins C and D can promote calcium stone formation.
Probenecid increases urinary uric acid and poses a risk for calcium or uric acid stones.
On the other hand, triamterene, certain protease inhibitors and guaifenecine/ephedrine can cause formation of stones composed of the drug or its metabolites.

21
Q

Interpretation of Ua and CS for stone formers

A

urease-producing bacteria suggests struvite stones
high urine pH suggests calcium phosphate or struvite stones
low urine pH suggests uric acid stones
hexagonal crystals indicate cystine stones
coffin-lid shaped crystals are pathognomonic for struvite stones.

22
Q

serum panel for stone formers

A 
sodium
    potassium
    chloride
    bicarbonate
    calcium
    creatinine
    uric acid
RTA --> High chloride, low bicarbonate and low K
hyperparathyroidism --> If high CA, suggest PTH
23
Q

when to order metabolic work-up for stone formers

A

High-risk patients include those with recurrent stones (including those with multiple or bilateral stones at initial presentation) and first time stone formers who have medical, genetic, anatomic or dietary predisposition to recurrent stone formation. In addition, any first time stone former who expresses interest in more extensive evaluation and directed medical therapy should be offered metabolic testing.

24
Q

metabolic workup for stone

A 
1. 24-hr urine x 2
then analysed with 9 criteria :
    total volume
 calcium, citrate, creatinine.
oxalate
 potassium,  pH
Sodium    
 uric acid

Urine urea nitrogen and urinary sulphate, which estimate animal protein intake, and urinary supersaturation, which provides an estimate of stone forming propensity, are considered optional tests.

25
Q

tx: hypercalciuria -> drugs and mechanism

A

hydrochlorothiazide 12.5-50mg twice daily
chlorthalidone 25-50mg per day
indapamide 1.25-5mg per day.
Increases calcium reabsorption from renal tubule; lowers urinary calcium.

26
Q

tx: hypercalciuria

A

potassium citrate 15-30milliequivalent twice daily
potassium citrate/citric acid (liquid)15-30milliequivalent 2-4 times daily
sodium bicarbonate 650mg 2-4 times daily.

Mode of action
Inhibits calcium oxalate and calcium phosphate crystallisation and reduces urinary ionised calcium; increases urinary citrate and urine pH.

27
Q

tx: hyperuricosria

A

allopurinol 100-300mg per day
febuxostat 40mg per day.

Mode of action
Inhibits xanthine oxidase; lowers serum and urine uric acid.

28
Q

tx: cystinuria

A

Drug and dose

d-penacillamine, start 250mg twice daily, titrate to effect
α-mercaptopropionyl glycine, start 200mg twice daily, titrate to effect. Thiol disulfide exchange; lowers urinary cystine.
29
Q

tx: struvite stones

A

acetohydroxamic acid 250mg 2-3 times daily

Mode of action
Inhibits bacterial urease; lowers urine pH and ammonia levels.

30
Q

Potential risks for stone events during pregnancy

A 
premature rupture of membranes
preterm labour and delivery
preeclampsia
hypertension
infection
pregnancy loss
31
Q

how to order low dose ct in pregnancy

A
  1. 2nd and third trimester only (most stone events appear)
  2. very low dose of radiation of only 4mGy, while a dose of less than 50mGy is thought to be safe for the duration of pregnancy
32
Q

expectant management for stone events in pregnancy

A
  1. Good pain control
  2. ability to tolerate food
  3. no signs of infection
  4. a stable uncomplicated pregnancy
  5. stone burden less than 1cm
  6. normal kidney
33
Q

mainstay of stone tx for pregnancy pxs

A

acetaminophen, hydration,anti-nausea, narcotics

Avoid NSAIDS –> may cause premature closure of ductus arteriosus and effects on renal development.

34
Q

anatomical variation of horseshoe kidney

A
  1. Pelvis and ureters of the horseshoe kidney are usually anteriorly placed
  2. calyces are normal in number,but they are atypical in orientation (pointing posteriorly)
  3. ureter may have a high insertion on the renal pelvis and a characteristic bend as it crosses over and anterior to the isthmus.
  4. vascular supply can be variable both in terms of number and origin of vessels.
    4 characteristics that might cause stasis and obstruction
35
Q

Medical treatment of stones (bladder), however, bear in mind that medical treatment of bladder stones is time consuming and impractical

A
  1. Hemiacidrin - > potent irreversible urease inhibitor, for struvite
  2. Sodium or potassium citrate -> URic acid stones
  3. Direct irrigation with sodium bicarbonate
36
Q

It has been suggested that stones greater than __ in normal bladder, augmented bladder or neobladder require open surgery.

A

4 cm

BJUI (5 decks)

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