POSTRENAL AKI

Question 1

When does Postrenal AKI occur?

Answer 1

When there’s partial or complete OBSTRUCTION of urinary flow sec to functional or structural derangements anywhere from the RENAL PELVIS to the TIP OF THE URETHRA

Question 2

True or False. Preserved urine output means there’s no obstruction.

Answer 2

FALSE. GFR is 2x higher in magnitude than the urine output hence preserved UO may mask a decreased GFR due to the obstruction

Question 3

In healthy individuals, AKI will occur only if both kidneys are affected by the obstruction. True or False.

Answer 3

True

Question 4

When will AKI due to unilateral obstruction occur?

Answer 4

If there’s significant underlying CKD or reflex vasospasm of the contralateral kidney (rare).

Question 5

Causes of obstruction in Postrenal AKI

Answer 5

-Bladder neck obstruction
(BPH, prostate ca, neurogenic bladder, anticholinergic drugs)
-obstructed foley cath
-blood clots
-calculi
-urethral strictures
-ureteric obstruction
(-INTRALUMINAL ex. calculi, blood clots, sloughed renal papillae
-INFILTRATION of the wall ex. neoplasia
-EXTERNAL COMPRESSION ex. retroperitoneal fibrosis, neoplasia, abscess, surgical damage)