Urology: Urinary Tract Obstruction Flashcards
where can this obstruction damage?
from the renal calyces to the urethral meatus
classification of a urinary tract obstruction
- partial/complete
- unilateral/bilateral
what are the types of obstructing lesions?
- luminal
- mural
- extra-mural
what happens if there is an obstruction?
- the tract proximal to the obstruction dilates
- dilatation of the renal pelvis and calyces is hydronephrosis
what are the luminal causes of obstruction?
- calculus
- blood clot
- sloughed papilla
- tumour of the renal pelvis or ureter bladder tumour
what are mural causes of obstruction?
- pelviureteric neuromuscular dysfunction
- ureteric stricture
- ureterovesical stricture
- congenital megaureter
- congenital bladder neck obstruction
- neuropathic bladder
- urethral stricture
- congenital urethral valve
- pin-hole meatus
what are extramural causes of obstruction?
- pelviureteric compression
- tumours of surrounding organs
- diverticulitis
- aortic aneurysm
- retroperitoneal fibrosis
- accidental ligation of the ureter
- retrocaval ureter
- prostatic obstruction
- phimosis
in which population is renal tract obstruction more common?
elderly men due to the frequency of bladder outflow obstruction due to prostatic disease
unilateral causes of hydronephrosis
- pelviureteric junction obstruction
- congenital pelviureteric junction obstruction
- aberrant renal vessels
- calculus
- tumours of the renal pelvis
- ureteric obstruction: calculus, ureteric invasion, iatrogenic
bilateral causes of hydronephrosis
- urethral valves
- urethral or meatal stenosis
- prostatic enlargement
- extensive bladder tumours
- retroperitoneal fibrosis
pathophysiology of an urinary tract obstruction
- if urine is still being produced, there is an increase in the intraluminal pressure, a dilatation proximal to the obstruction site, compression of the renal parenchyma, eventually reducing it to a thin rim and resulting in a decrease in the size of the kidney
- acute obstruction is followed by transient renal arterial vasodilatation succeeded by vasoconstriction
symptoms of upper tract obstruction
- loin pain (dull/sharp)
- exacerbated by a high urine volume, diuretics, distension
- loin tenderness (in acute obstruction)
- chronic obstruction: flank pain, renal failure, superimposed infection, polyuria
what happens in bilateral obstruction?
complete anuria
symptoms of bladder outflow obstruction
- hesistancy
- diminished force of the urinary stream
- terminal dribbling
- sense of an incomplete bladder
- if infection occurs: increased frequency, urgency, urge incontinence, dysuria, passage of cloudy smelly urine
signs of renal obstruction
- loin tenderness
- palpable enlarged hydronephrotic kidney
- enlarged bladder can be felt if there is retention, dull to percussion
- examination of genitalia is essential
investigation of obstruction
- U&E
- creatinine
- urine for MC&S
- ultrasound
- CT scan (if hydronephrosis or hydroureter are suspected)
- radionuclide imaging (functional assessment of the kidney)
what do the routine investigations show in acute obstruction
- raised serum urea or creatinine
- hyperkalaemia
- anaemia of chronic disease
- haematuria
what can an AXR be used for?
looking for radiolucent calculi
what can a CT scan be used for?
visualise uric acid or radiolucent stones
why is an ultrasound used in an obstruction?
upper urinary tract dilatation
why are radionuclide studies done in an obstructive picture?
differentiates between true obstructive nephropathy from a false obstructive picture with retention
why are antegrade pyelography and ureterography used?
define the site and cause of obstruction
why are cystoscopy, urethroscopy and urethrography used?
used to directly focus on the obstructing lesion from within the organ
treatment of urinary obstruction
- nephrostomy (upper obstruction)
- treat the underlying cause
- urethral or suprapubic catheter (lower obstruction)
aftermath of relieving the obstruction
diuresis - due to the high amounts of ANP in the bloods, the osmotic effect of the electrolytes retained in the blood and the high blood volume. severe diuresis can lead to water, Na and K depletion, which need supplementation
complications of ureteric stenting
- stent-related pain
- trigonal irritation
- haematuria
- fever
- infection
- tissue inflammation
- encrustation
- biofilm formation
- obstruction
- kinking
- ureteric rupture
- stent misplacement
- stent migration
- tissue hyperplasia
what is retroperitoneal fibrosis?
The ureters become embedded in dense retroperitoneal fibrous tissue with resultant unilateral
or bilateral obstruction
cause of periaortitis
- idiopathic retroperitoneal fibrosis
- inflammatory aneurysms of the abdominal aorta
- perianeurysmal RPF
what is associated to periaortitis?
- drugs
- autoimmune disease
- smoking
- asbestos
treatment for periaostitis?
- retrograde stent placement to relieve obstruction
- ureterolysis (separating the ureters from the retroperitoneal tissue)
- immunosuppression
