[12] Urinary Tract Obstruction Flashcards
What are the categories of causes of urinary tract obstruction?
Luminal
Mural
Extramural
What are the luminal causes of urinary tract obstruction?
Stones
Blood clots
Sloughed papilla
What are the mural causes of urinary tract obstructions?
Congential or acquired stricture
Tumour
Neuromuscular dysfunction
What tumours can cause urinary tract obstructions?
Renal
Ureteric
Bladder
What are the extramural causes of urinary tract obstruction?
Prostatic enlargement
Abdominal/pelvis mass or tumour
Retroperitoneal fibrosis
How does acute upper urinary tract obstruction present?
Loin to groin pain
How does acute lower urinary tract obstruction present?
Severe suprapubic pain with distended, palpable bladder
What causes suprapubic pain and palpable bladder in acute lower urinary tract obstruction?
Bladder outflow obstruction
How does chronic upper urinary tract obstruction present?
Flank pain
Renal failure
How does chronic lower urinary tract obstruction present?
Frequency Hesitancy Poor stream Terminal drippling Overflow incontinence
What may be found on examination in chroinc lower urinary tract obstruction?
Distended, palpable bladder
Sometimes large prostate on PR
What investigations are done in urinary tract obstruction?
Bloods
Urine dip and MC&S
Imaging
What imaging is done in urinary tract obstruction?
Ultrasound
Anterograde/retrograde ureterograms
Radionucleotide imaging
CT/MRI
What might be found on US in urinary tract obstruction?
Hydronephrosis or hydroureter
What do anterograde/retrograde ureterograms allow in urinary tract obstruction?
Therapeutic drainage
What is the purpose of radionucleotide imaging in urinary tract obstruction?
Check renal function
How is an upper urinary tract obstruction managed?
Nephrostomy
Ureteric stent
How is a lower urinary tract obstruction managed?
Urethral or supra-pubic catheter
What might happen following catheterisation in a lower urinary tract obstruction?
May be a large post-obstructive diuresis
What are the common complications of ureteric stents?
Infection
Haematuria
Trigonal irritation
Encrustation
What are the rare complications of ureteric stents?
Obstruction
Ureteric rupture
Stent migration
What are the causes of urethral stricture?
Trauma
Infection
Chemotherapy
Balantitis xerotica obliterans
Give two examples of urethral trauma that can cause strictures
Instrumentation
Pelvic fractures
Give an example of an infection that can cause urethral strictures
Gonorrhoea
How do urethral strictures present?
Hesitancy Strangury Poor stream Terminal dribbling Pis en deux
What is done on examination in urethral stricture?
PR to exclude prostatic cause
Palpate urethra through penis
Examine meatus
What investigations are done in urethral stricture?
Urodynamics
Urethroscopy and cystoscopy
Retrograde urethrogram
What is found on urodynamics in urethral strictures?
Decreased peak flow rate
Increased micturition rate
How are urethral strictures managed?
Internal urethrotomy
Dilatation
Stent
Why might obstructive uropathy go unnoticed for days?
Because acute retention on a chronic background may not produce pain
What might serum creatinine be in obstructive uropathy?
Up to 1500uM
What is the long-term outcome of obstructive uropathy?
Renal function should return to normal over days, but some background impairment may remain
What are the complications of obstructive uropathy?
Hyperkalaemia Metabolic acidosis Post-obstructive diuresis Na and HCO3 losing nephropathy Infection
What causes post-obstructive diuresis?
Kidneys produce a lot of urine in the acute phase after relief of obstruction
What do you need to ensure with post-obstructive diuresis?
Need to ensure you keep up with loses to avoid dehydration
What might cause Na and HCO3 losing nephopathy in obstructive uropathy?
Post-obstructive diuresis might cause loss of Na and HCO3
What management might Na and HCO3- losing nephropathy require?
Replacement with 1.26% NaHCO3
