Urinary Tract Obstruction

Question 1

posterior urethral valve

Answer 1

• obstructing membrane over the posterior urethra in males as a result of abnormal utero development
• causes bladder outlet obstruction and bilateral hydronephrosis
• there is bladder wall hypertrophy and diverticula form

Question 2

management of posterior urethral valve

Answer 2

catherisation

Question 3

what can hypoxa in utero cause

Answer 3

ischaemia and scarring, leading to pelvi-ureteric stenosis

Question 4

complications of prolonged bladder obstruction

Answer 4

• Prolonged bladder obstruction can lead to hypertrophy of the detrusor muscle - trabeculation, and eventually diverticulum formation
• Atonic bladder – doesn’t empty properly due to detrusor muscle hypofunction

Question 5

management of urethral stricture

Answer 5

urethotomy of anastomotoic urethroplasty

Question 6

which medications can cause urinary retention

Answer 6

• anti-cholinergics eg oxybutynin and tolterodine
• sympathomimetic drugs eg cocaine, MDMA

Question 7

management of acute urinary retention

Answer 7

• catheter and start an alpha blocker (to increase voiding success) for at least 2 days before catheter is removed
• if there is painful retention with <1l residue and normal serum electrolytes, a TWOC can be tried during the same admission (with alpha blocker)

Question 8

post obsructive diuresis

Answer 8

• Polyuric state in which copious amounts of salt and water are eliminated after the relief of a urinary tract obstruction
• Bladder adapts physiologically to obstructed outflow, when mechanical obstruction is removed the physiological mechanisms are still in place
• Osmotic diuresis

Question 9

management of post obstructive diuresis

Answer 9

• monitor fluid balance and beware of hypovolaemia if urine output >200ml/hour
• usually resolves within 24-48 hours, severe cases may require IV fluid and sodium replacement

Question 10

obstructive uropathy

Answer 10

• the blockage of urinary flow, which may afect one or both of the kidneys
• if only one kidney is affected, urinary output may be unchanged and serum creatinine can be normal

Question 11

define hydronephrosis

Answer 11

• the dilation of the renal pelvis and can be present with/out obstruction