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Flashcards in Urinary tract obstruction Deck (14):

common causes of UT obstruction

prostatic obstruction
gynaecological cancer and calculi
inflammatory (TB, infec)
Congenital (cysts)


clinical features upper urinary tract obstruction

dull ache in the flank or loin - provoked by inc in urine volume

complete anuria = strongly suggestive of complete bilateral obstruction

partial obstruction = polyuria as a result of tubular damage and impairment of concentrating mechanisms


clinical features bladder outlet obstruction

poor stream
terminal dribbling
sense of incomplete emptying
retention with overflow is characterised by the frequent passage of small quantities of urine
infection usually occurs


what might be found on examination in UT obstruction

enlarged bladder or hydronephrotic kidney
pelvic (for malignancy) and rectal (for prostate) exam is essential in determining the cause of obstruction


investigations UT obstruction

USS and spiral CT to look at site of obstruction


management UT obstruction

surgery if persistent
sometimes definitive relief of obstruction not poss = catheter needed


what might happen after elimination of the obstruction

a massive post op diuresis (lots of wee), resulting partly from a solute diuresis from salt and urea retained during obstruction & partly from the renal concentrating defect


obstructive uropathy

functional or anatomical obstruction of urine flow at any level of the urinary tract


supravesical obstruction

above the level of the bladder


infravesical obstruction

below the level of the bladder


haemodynamic changes with unilateral ureteral occlusion

1. inc in RBF and hydraulic pressure of fluid in the tubule & collecting system pressure for first 1-2hr
2. 3-4h pressures remain elevated by RBF declines
3. 5h further RBF decline and dec in pressure


haemodynamic changes with bilateral ureteral occlusion

small inc in RBF for 90min followed by profound dec
accumulation of vasoactive substances = preglomerular vasodilation and post glomerular vasoconstriction
when obstruction released GFR an RBF remain depressed due to persistent vasoconstriction of afferent arteriole
= post op diuresis (bigger in BUO than UUO)


effects of obstruction on tubular function

dysregulation of aquaporin channels = polyuria & impaired concentrating capacity
sodium transport decreased = post obstructed kidneys impaired ability to concentrate and dilute urine


sequelae from obstruction

release of angiotensin 2, cytokines and growth factors = changes to kidney
tubulointerstitial fibrosis
tubular atrophy and apoptosis
interstitial inflammation