9. Obstruction And Urolithiasis Flashcards
What do urinary tract obstructions increase the risk of?
UTI
Reflux
Stone formation
What can cause urinary retention?
Calculi Pregnancy Benign prostatic hypertrophy Recent surgery Drugs Urethral strictures Pelviureteric junction obstruction Pelvic masses Constipation Inflammation Tumours Neurogenic disorders
How can pregnancy cause urinary retention?
High levels of progesterone relax muscle fibres in renal pelvis and ureters and cause a dysfunctional obstruction
Can also put pressure on ureters, blocking them
What is the presentation of acute urinary retention?
Painful inability to void
Residual volume 300-1500ml
What is the presentation of chronic urinary retention?
Painless
May still be voiding
Residual volume 300-4000ml
What is the management of acute urinary retention?
Catheterise and record residual urinary volume
History
Examination (abdomen, ext. genitalia, DRE)
Urine dip
U and E
Treat any obvious cause (constipation)
BPH - alpha blockers
What is the management for chronic urinary retention?
Catheterise and record residual volume History Examination Urine dip, U and E Plan for long-term catheterisation or intermittent self catheterisation
How does high pressure chronic urinary retention present?
Abnormal U andE
Hydronephrosis
Repeat episodes can cause permanent renal scarring and CKD
Unable to void on own
What is the presentation of low pressure chronic urinary retention?
Normal renal unction
No hydronephrosis
Unable to void on own
What is post-obstructive diuresis?
Following resolution of urinary retention through catheterisation
Kidneys can often over-diuresis
Can lead to worsening AKI
How do you avoid post-obstructive diuresis?
Urine output should be monitored for 24hrs post catheterisation
Patients with high urine volumes should be supported with IV fluids
What is hydronephrosis?
Dilation of renal pelvis and calyces due to obstruction at any point in urinary tract causing increased pressure and blockage
Can be unilateral (upper urinary tract obstruction) or bilateral (lower urinary tract obstruction)
What happens as a result of hydronephrosis?
Progressive atrophy of kidney develops, back pressure from obstruction is transmitted to distal parts of nephron
GFR declines and if obstruction is bilateral, patient goes into renal failure
What does an obstruction at the pelviureteric junction cause?
Hydronephrosis
What does an obstruction at the ureter cause?
Hydroureter, developing into hydronephrosis
What does an obstruction of the bladder neck/urethra cause?
Bladder distension with hypertrophy, eventually leading to hydroureter and thus hydronephrosis
What can cause acute ureteric obstruction?
Usually calculus, but can be due to blood clots or sloughed papilla
What does acute ureteric obstruction result in and lead to?
Results in renal colic
Leads to acute renal failure if bilateral
Pyonphrosis can develop
What does acute ureteric obstruction present as?
Anuria
Oliguria
How is an upper urinary tract obstruction diagnosed?
CT or USS - show structure not function
Diuretic renography is a functional test
How is the upper urinary tract drained?
Nephrostomy
JJ stent
What is urolithiasis?
Urinary calculi
Dehydration increases concentration of urine and is a predisposing factor
Where can urolithiasis form?
Anywhere in urinary tract
Most common: pelviureteric junction, pelvic brim, vesicoureteric junction
How are urolithiasis diagnosed?
CT scan of kidneys, ureters and bladder
What are the 5 types of calculi?
Calcium oxalate stones - hypercalcaemia, hyperparathyroidism, hyperoxaluria
Mixed calcium phosphate and calcium oxalate stones - alkaline urine
Magnesium ammonium phosphate stones - urea splitting bacteria
Uric acid stones - gout and myeloproliferative disorders
Cystine stones - inherited cystinuria
What is the clinical presentation of stones?
Renal stones - continuous dull ache in loins
Ureteric stones - renal colic, radiates from loin to groin, sweaty, pale, restless, nausea, vomiting
Bladder stones - strangury
What is the treatment for stones?
Adequate analgesia and high fluid intake
Stones of 4-5mm or less pass spontaneously
Larger stones may require surgical intervention
Extracorporeal shock wave lithotripsy
Ureteroscopic destruction or removal
Open surgical removal
Endoscopic removal of stone (PCNL)
