343 Urinary Tract Obstruction

Question 1

3 Normal points of narrowing that are are common sites of obstruction

Answer 1

ureteropelvic and ureterovesical junctions,
bladder neck, and
urethral meatus

Question 2

most common cause of bilateral hydronephrosis in boys (child)

Answer 2

Posterior urethral valves

Question 3

most common Congenital malformation in GU tract

Answer 3

narrowing of the ureteropelvic junction and abnormal insertion of the ureter into the bladder

Question 4

Diagnostic exam that is useful in evaluating incomplete emptying and bladder neck and urethral

Answer 4

voiding cystourethrogram

Question 5

Acute effects of BILATERAL tubular obstruction

Answer 5

PAIN
azotemia
Anuria or oliguria
Increased urine concentration due to Na urea and water reabsorption

Question 6

Chronic effects of BILATERAL ureteral obstruction

Answer 6

Increased RAAS activation —> Hypertension
Decreased medullary osmolarity —> Decreased concentrating ability —> Polyuria and nocturia
AVP insensitive polyuria—> Acquired nephrogenic diabetes insipidus
Decreased salt reabsorption—> Natriuresis

Question 7

Partial bilateral UTO often results in What metabolic disturbances

Answer 7

acquired distal renal tubular acidosis—>H secretion via H - ATPases
hyperkalemia—> Decreased K secretion due to ENaC channels
renal salt wasting—> decreased function of the ENaC, in the apical membrane of neighboring collecting duct principal cells — natriuresis

Question 8

Release of obstruction causes changes such as

What you need to watch out

Answer 8

Postobstructive diuresis
Potential volume depletion
Electrolyte imbalance due to losses of Na K PO4 Mg and water

Question 9

First Diagnostic test for obstruction? 90% sensitive and specific

Answer 9

KUB UTZ

Question 10

Expected Urine sediment results in obstruction

Answer 10

Normal

Question 11

Hydronephrosis may be absent if obstruction is less than how many hours

Answer 11

48 hours

Question 12

Principles of management for UTO

Answer 12

If infection is present, immediate relief of obstruction is warranted
If no infection, acid-base, fluid, and electrolyte status is restored prior to surgery

Question 13

PARTIAL return of glomerular filtration rate is expected following relief of complete obstruction after how many weeks?
Goal must be to relieve obstruction LESS THAN this duration

Answer 13

1 to 2 weeks

Question 14

Irreversible damage is expected on how many weeks of obstruction?

Answer 14

After 8 weeks

Question 15

Diagnostic test that may be use to predict the reversibility of renal dysfunction

Answer 15

renal radionuclide scan

Question 16

Management of postobstructive diuresis

Answer 16

Strict output monitoring
Serum and urine sodium and osmolal concentration monitoring to guide appropriate IV replacement—>0.45% saline is often used
Replacement with intravenous fluids in amounts less than urinary losses
WOF hypernatremia, dehydration, vascular collapse