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Yr 3 renal > urinary tract calculi > Flashcards

urinary tract calculi Flashcards

1
Q

definition of urinary tract calculi

A

crystal deposition in the urinary tract

also known as nephrolithiasis

stones form in collecting ducts and deposited anywhere from renal pelvis to urethra.

classically at pelviureteric junction, pelvic brim, vesicoureteric junction

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2
Q

aetiology of urinary tract calculi

A

many cases idiopathic

metabolic - hyperclaciuria, hyperuricaemia, hypercystinuria, hyperoxaluria

infection - hyperuricaemia

anatomic factors - hypercystinuria, hyperoxaluria

drugs - indinavir - only stones that dont show on CT, look more like a filling defect

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3
Q

RF for urinary tract calculi

A

low fluid intake

structural urinary tract anomalies (eg horseshoe kidney, medullary sponge kidney)

FH increase risk 3fold - x-linked nephrolithiasis and Dent’s disease (proteinuria, hypercalciruria and nephrocalcinosis), cystinuria/cystine stones

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4
Q

pathophysiology of urinary tract calculi

A

calculi formed by supersaturation of urine by stone forming compounds

allowing crystallisation around a focus (eg infection, tumour, foreign bodies)

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5
Q

main types of renal tract calculi

A

calcium oxalate - commonest, sharp projections = cause trauma - known as ‘mulberry stones’

struvite (Mg, ammonia, phosphate) - common, smooth and dirty white, associated with urea splitting bacteria eg proteus, pseudomonas, klebsiella, may form ‘staghorn’ stones in kidneys

calcium phosphate

urate - uncommon, hard, smooth, brown, faceted, occurs in acidic urine

hydroxyapatite

brushite

cystine - uncommon, white and translucent, occurs in acidic urine

mixed

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6
Q

importance of renal tract calculi

A

Pain

Infection – life threatening, gram -ve sepsis (pyelonephrosis)– ITU/surgery

Renal damage if blockage – kidney wont drain well = damage

Underlying met problems – gout uraemic acid stones, cystenuria – predispose hard stones, hyperparathyroidism

Anatomical problems – pelvioutero junction obstruction, urine stagnant/stasis, MSK, horseshoe kidney, ureteric stricture – more chance could form stones

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7
Q

area of stone impaction

A

o PUJ – between pelvis and ureter

o Midureter – where ureter crosses iliac vessels, natural constriction of ureter

o Intramural ureter at entrance to bladder

• If go through all 3 constrictions = pass

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8
Q

epidemiology of renal tract calculi

A
  • common
  • Caucasian
  • 1% of hospital admissions
  • prevalence: 2-3% of the population per year
  • male
  • lifetime risk 10-15% in men, 5-10% women
  • 20-50yrs
  • bladder stones more common in developing countries, upper tract stones in developed countries
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9
Q

sx of urinary tract calculi

A

often asymptomatic

severe ‘loin to groin’ flank pain (renal, caliceal or ureteric colic)

often cant lie still (differentiates from peritonitis)

may be associated with nausea and vomiting when severe

urinary urgency, frequency or retention

haematuria

obstruction of kidney - felt in loin between rib 12 and lateral edge of lumbar muscles (like intercostal nerve irritation pain, not colicky, worsened by specific movements/pressure on a trigger spot)

obstruction of mid-ureter - mimic appendicitis/diverticulitis

obstruction of lower-ureter - symptoms of bladder irritability, pain in scrotum, penile tip or labia majora

obstruction of bladder or urethra - cause pelvic pain, dysuria, strangury (desire but inability to void) +- interrupted flow

infection can co-exist - increased risk if impaired voiding eg UTI, pyelonephritis (fever, rigor, loin pain, nausea, vom), pyonephrosis (infected hydronephrosis)

proteinuria

sterile pyuria

anuria

nausea and vom

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10
Q

signs of urinary tract calculi

A

loin or lower abdominal tenderness, without signs of peritonism

leaking AAA is most important ddx to consider

signs of systemic sepsis if there is obstruction and infection above a stone

abdo soft

pain is spectrum - if acutely blocking kidney = pain

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11
Q

Ix for urinary tract calculi

A

bloods

urine

radiology

IVU

US

non-enhanced spiral CT

isotope renography - eg with DPTA or DMSA; assessment of kidney function in complex stone disease

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12
Q

bloods for urinary tract calculi

A

FBC - raised WCC indicates possible infection

U&E

urate

PO3-4 (if raised - need more investigation for causes)

Ca

glucose

bicarb

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13
Q

urine for urinary tract calculi

A

dipstick (if no haematuria diagnosis is questionable)

culture and senstivity

24hr urine collection - for calculi and measure calculi-forming ion levels, ca, oxalate, urate, citrate, Na, creatinine

MC&S

pH and nitrites - show UTI

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14
Q

radiology for urinary tract calculi

A

KUB - 80% stones are radio-opaque and will show on plain radiograph of lower abdo or pelvis

  • w/o contrast because the contrast and stones are white

plane XR - radioopaque shadow between transverse processes because ureter runs across tip of the transverse processes of lumbar vertebrae

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15
Q

IVU for urinary tract calculi

A

enables visualistion of the kidneys and ureters

if ureteric stone, can be a delayed dense nephrogram phase, later films showing a dilated pelvicaliceal system and a standing column of contrast down to the stone

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16
Q

US for urinary tract calculi

A

ureteral dilation or hydronephrosis from an obstructive uropathy

not sensitive for detecting smaller stones

used when IVU contrast is CI

17
Q

Mx of acute urinary tract calculi

A

analgesia (NSAID and opiate) eg diclofenac

AB eg poperacillin/tazobactam or gentamycin if infection

fluids - IV or oral

urine collection to collect any calculi for analysis

suitable for stones not causing obstruction (<5mm will pass)

obstructed infected kidney = emergency - need urgent relief of obstruction

placement of percutaneous nephrostomy under radiological guidance with AB and other supportive measures

18
Q

what size stones pass spontaneously

A

stones <5mm in lower ureter 90-95% pass spontaneously

19
Q

medical expulsive therapy for urinary tract calculi

A

nifedipine or a-blockers (tamsulosin) promote expulsion and reduce pain relief requirements

  • distal ureter rich in a receptors, so this relaxes sm of distal ureter

alkanise urine: K citrate if uric acid to dissolve

20
Q

removal of calculi

A

active intervention indicated if calculi obstructs or there is continuing pain or pyrexia

urethroscopy

  • flexible or rigid urethroscope passed into the bladder and up ureter to visualise the stone
  • removed by basket, grasper or broken up with laser, US or other methods
  • if stone is impacted and cannot be removed a JJ stent is placed to ensure urine drainage

extracorporeal shock wave lithotripsy

  • non-invasive, quick, no anaesthesia
  • electromagnet or piezoelectric shock wave is focused onto calculus to break it up into smaller fragments - they can pass spontaneously
  • suitable if <2cm as long as no obstruction - if bigger = too many fragments = stuck
  • if stone hard - wont break
  • have to pass the stone themselves - might be painful

percutaneous nephrolithotomy

  • for large complex stones eg stag-horn calculi
  • following creation of nephrostomy tract, a nephroscope is introduced and allows disintegration and removal of stones
  • nephrostomy tube left in situ for 1-2 days post op with a nephrostogram perfomed to ensure stone removal and confirm normal ureteric drainage

open nephro-, pyelo-, ureterolithotomy

  • less commonly performed
  • usually for complex stones

nephrectomy - may be indicated in a non-functioning kidney

21
Q

treatment of cause of urinary tract calculi

A

parathyroidectomy

dietary ca or oxalate restriction - dont cut out dairy just no supplements

less salt, animal protein (red meat)

allopurinol

urine alkanisation with oral potassium citrate - dissolves urate and cystine stones

treat UTI

22
Q

indications for urgent intervention with urinary tract calculi

A

infection and obstruction - percutaneous nephrostomy or ureteric stent may be needed to relieve obstruction

urosepsis

intractable pain or vomiting

impending AKI

obstruction of solitary kidney

bilateral obstructing stones

23
Q

admit to hospital for urinary tract calculi if:

A
  • Single kidney
  • Pyrexia
  • Continuing pain
  • Renal impairment
  • Pregnancy
  • Large stone/severe obstruction – need removal
  • infected and obstructed
  • vomiting/dehydration
  • social circumstance

otherwise discharge with stone clinic

24
Q

complications of urinary tract calculi

A

of stones - infection especially pyelonephritis, septicaemia, urinary retention

of ureteroscopy - perforation, false passage

of lithotripsy - pain, haematuria, Steinstrasse (ureteric obstruction caused by a column of stone fragments), renal injury, raised BP and DM

25
Q

Px of urinary tract calculi

A

generally good

infection of renal calculi can potentially lead to irreversible renal scarring

recurrence rate is about 50% within 5yrs

26
Q

classification of urinary tract calculi

A

size <5mm, 5-20mm, >20mm, staghorn

location - renal (calcyceal, pelvic, diverticular), ureteric

XR characteristics - radiolucent (uric acid), radioopaque

stone composition: CaOx, CaP, uric acid, cysteine, indinavir, infection magnesium ammonium phosphate/struvite

27
Q
A

Blocked R kidney – not on XR – uric acid stone

28
Q
A

Stone in VUJ lowest part of ureter

29
Q

conservative Mx of urinary tract calculi

A

observe if non-sx and non-obstructive

metabolic screen

30
Q

follow up issues with urinary tract calculi

A

renal deterioration if complete obstruction

JJ encrustation <6mo in stone formers

50% recurrent stones - fluid intake advice

40% of conservatively managed stones will enlarge - monitor by imaging

31
Q

summarise obstructive pyonephrosis

A

= obstruction and infection

risk of fatal gram -ve sepsis

immediate resus and IV AB

culture

urgent imaging - KUB and US

discuss with urology

consider urgent nephrostomy or JJ stent

monitor in HDU

32
Q

Mx of obstructive pyonephrosis once stable

A

Imaging to determine cause - CT KUB, nephrostigram

antegrade stent

plan uretoscopy/ESWL/PCNL

may need drainage if perinephric abscess

may need nephrectomy if XGP or EPN

Yr 3 renal (18 decks)

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