Obstructions + Urolithiasis Flashcards
What does a unitary tract obstruction increase your risk of?
UTI
Reflux
Stone formation
Causes of urinary retention
- calculi
- pregnancy
- benign prostatic hypertrophy
- recent surgery
- drugs
- urethral strictures
- constipation
- pelvic masses or tumours
- inflammation of lower urinary tract
- issues with spinal cord
How can pregnancy causes urinary retention?
- high levels of progesterone relax muscle fibres in renal pelvis + ureters
- causes dysfunctional obstruction
Describe acute urinary retention
Painful
Inability to void
Residual volume 300-1500ml
Describe chronic urinary retention
Painless
May still be voiding
Residual volume 300-4000ml
Acute vs chronic urinary retention
- Acute: painful + unable to void
- Chronic: painless + may be able to void
Management of acute urinary retention
- catheterise + record residual volume
- history
- abdomen + external genitalia exam
- urine dipstick + U&Es
- treat any obvious cause
- BPH - alpha blocker
Management of chronic urinary retention
- catheterise + record residual volume
- exam
- urine dipstick + U&Es
- long term catheterisation
high pressure:
- abnormal U&Es, hydronephrosis
- repeat episodes can cause permanent renal scaring + CKD
low pressure:
- normal renal function
- no hydronephrosis
What is a staghorn calculus?
Renal stone in the renal collecting system
What are the most common locations of stones in the urinary tract?
Pelviureteric junction
Pelvic brim
Vesicoureteric junction
What is acute on chronic urinary retention?
Patient has chronic UR but something else happens + causes acute UR so patient has both
What is hydronephrosis?
- Dilation of the renal pelvis + calyces
- due to obstruction at any point along urinary tract > increased pressure + blockage > urine accumulates in kidneys
- unilateral or bilateral
What is unilateral hydronephrosis caused by?
Upper urinary tract obstruction
e.g. in ureter
What is bilateral hydronephrosis caused by?
Obstruction in lower urinary tract
e.g. enlarged prostate
What is post obstructive diuresis?
Kidneys eliminate excess amounts of water after resolution of urinary retention through catheterisation
Management of patients with post obstructed diuresis
- monitor urine output for 24hours post catheterisation
- support with IV fluids if losing high urine volumes
What type of AKI can hydronephrosis cause?
Post renal AKI
Why does GFR decline in hydronephrosis?
- accumulation of urine in kidneys + calyces
- back pressure from obstruction transmitted to distal parts of nephron
- increases pressure pushing back against hydrostatic pressure in glomeruli
- GFR declines
What does an obstruction at the ureter cause?
Hydroureter
Develops into hydronephrosis
What does an obstruction in bladder neck cause?
Bladder distension with hypertrophy
Then hydroureter
Then hydronephrosis
What pain does acute ureteric obstruction cause?
Renal colic
What can cause an acute ureteric obstruction?
Calculus (mainly)
Blood clots
Sloughed papilla
What is pyonephrosis?
Infected obstructed kidney
Pus, fluid + inflammation in kidney
What may failure of prompt treatment in pyonephrosis cause?
Death from sepsis
Permanent loss of renal function
Diagnosis of upper urinary tract obstruction
CT or US
Diuretic renography
What can be used to drainage the upper urinary tract?
Nephrostomy
JJ stent
What is urolithiasis?
Urinary stone
What demographic do urinary stones most commonly effect?
Men
Caucasians
Diagnosis of urinary stones
CT scan of kidneys, ureters + bladder
What are the types of urinary stones?
- calcium oxalate stone (most common)
- mixed calcium phosphate + calcium oxalate stone
- magnesium ammonium phosphate stones
- uric acid stone
- cystine stone
Types of urinary stones + what is associated with each type
- calcium oxalate: hypercalcaemia, hyperparathyroidism, hyperoxaluria
- mixed calcium phosphate + calcium oxalate: alkaline urine
- magnesium ammonium phosphate: urea splitting bacteria
- uric acid: gout + myoproliferative disorders
- cystine: inherited cystinuria
Clinical presentation of urinary stones (renal, ureteric + bladder)
- renal stones: continuous dull ache in lions
- ureteric stones: renal colic (radiates from loin to groin), sweaty, restless with N+V
- bladder stones: strangury
- recurrent UTI, haematuria or rental failure
What is strangury?
Urge to pass something that will not pass
(Feeling like they need to pee all the time)
Treatment of urinary stones
- analgesia
- high fluid intake
- urine sieved for analysis
- surgery for larger stones
- thiazide
What drug can be used to decrease urinary stones?
Thiazide
Increases absorption of Na+
Interventional treatment of urinary stones
- extracorporeal shock wave lithotripsy
- ureteroscopy
- percutaneous nephrolithotomy
What is extracorporeal shock wave lithotripsy?
- non-invasive procedure
- shock waves break down stones into smaller fragments > easier to pass
- suitable for smaller stones <2cm
What is ureteroscopy?
- for stones in ureter + smaller stone in kidney
- use of thin, flexible instrument to visualise + access stones
- can remove or fragment stones
What is percutaneous nephrolithotomy?
- for larger stones in kidney >2cm
- invasive
- small incision to access + remove or breakdown stones
What is the most common composition of ureteric stones?
Calcium oxalate stone
What factors predispose the development of ureteric stones?
Low urine volume
Hypercalcaemia
Hyperoxaluria
(Calcium oxalate is most common)
What has high levels of oxalate in?
Tea
Features of hypercalcaemia
‘Bones, stones, thrones, moans, groans’
- bone pain + increased fracture risk
- renal sones
- polyuria
- constipation
- confusion + mood disturbance
- abdominal pain
