9. Obstruction And Urolithiasis

Question 1

What do urinary tract obstructions increase the risk of?

Answer 1

UTI
Reflux
Stone formation

Question 2

What can cause urinary retention?

Answer 2

Calculi 
Pregnancy
Benign prostatic hypertrophy
Recent surgery
Drugs
Urethral strictures
Pelviureteric junction obstruction 
Pelvic masses
Constipation 
Inflammation
Tumours 
Neurogenic disorders

Question 3

How can pregnancy cause urinary retention?

Answer 3

High levels of progesterone relax muscle fibres in renal pelvis and ureters and cause a dysfunctional obstruction
Can also put pressure on ureters, blocking them

Question 4

What is the presentation of acute urinary retention?

Answer 4

Painful inability to void

Residual volume 300-1500ml

Question 5

What is the presentation of chronic urinary retention?

Answer 5

Painless
May still be voiding
Residual volume 300-4000ml

Question 6

What is the management of acute urinary retention?

Answer 6

Catheterise and record residual urinary volume
History
Examination (abdomen, ext. genitalia, DRE)
Urine dip
U and E
Treat any obvious cause (constipation)
BPH - alpha blockers

Question 7

What is the management for chronic urinary retention?

Answer 7

Catheterise and record residual volume
History
Examination
Urine dip, U and E
Plan for long-term catheterisation or intermittent self catheterisation

Question 8

How does high pressure chronic urinary retention present?

Answer 8

Abnormal U andE
Hydronephrosis
Repeat episodes can cause permanent renal scarring and CKD
Unable to void on own

Question 9

What is the presentation of low pressure chronic urinary retention?

Answer 9

Normal renal unction
No hydronephrosis
Unable to void on own

Question 10

What is post-obstructive diuresis?

Answer 10

Following resolution of urinary retention through catheterisation
Kidneys can often over-diuresis
Can lead to worsening AKI

Question 11

How do you avoid post-obstructive diuresis?

Answer 11

Urine output should be monitored for 24hrs post catheterisation
Patients with high urine volumes should be supported with IV fluids

Question 12

What is hydronephrosis?

Answer 12

Dilation of renal pelvis and calyces due to obstruction at any point in urinary tract causing increased pressure and blockage
Can be unilateral (upper urinary tract obstruction) or bilateral (lower urinary tract obstruction)

Question 13

What happens as a result of hydronephrosis?

Answer 13

Progressive atrophy of kidney develops, back pressure from obstruction is transmitted to distal parts of nephron
GFR declines and if obstruction is bilateral, patient goes into renal failure

Question 14

What does an obstruction at the pelviureteric junction cause?

Answer 14

Hydronephrosis

Question 15

What does an obstruction at the ureter cause?

Answer 15

Hydroureter, developing into hydronephrosis

Question 16

What does an obstruction of the bladder neck/urethra cause?

Answer 16

Bladder distension with hypertrophy, eventually leading to hydroureter and thus hydronephrosis

Question 17

What can cause acute ureteric obstruction?

Answer 17

Usually calculus, but can be due to blood clots or sloughed papilla

Question 18

What does acute ureteric obstruction result in and lead to?

Answer 18

Results in renal colic
Leads to acute renal failure if bilateral
Pyonphrosis can develop

Question 19

What does acute ureteric obstruction present as?

Answer 19

Anuria

Oliguria

Question 20

How is an upper urinary tract obstruction diagnosed?

Answer 20

CT or USS - show structure not function

Diuretic renography is a functional test

Question 21

How is the upper urinary tract drained?

Answer 21

Nephrostomy

JJ stent

Question 22

What is urolithiasis?

Answer 22

Urinary calculi

Dehydration increases concentration of urine and is a predisposing factor

Question 23

Where can urolithiasis form?

Answer 23

Anywhere in urinary tract

Most common: pelviureteric junction, pelvic brim, vesicoureteric junction

Question 24

How are urolithiasis diagnosed?

Answer 24

CT scan of kidneys, ureters and bladder

Question 25

What are the 5 types of calculi?

Answer 25

Calcium oxalate stones - hypercalcaemia, hyperparathyroidism, hyperoxaluria
Mixed calcium phosphate and calcium oxalate stones - alkaline urine
Magnesium ammonium phosphate stones - urea splitting bacteria
Uric acid stones - gout and myeloproliferative disorders
Cystine stones - inherited cystinuria

Question 26

What is the clinical presentation of stones?

Answer 26

Renal stones - continuous dull ache in loins
Ureteric stones - renal colic, radiates from loin to groin, sweaty, pale, restless, nausea, vomiting
Bladder stones - strangury

Question 27

What is the treatment for stones?

Answer 27

Adequate analgesia and high fluid intake
Stones of 4-5mm or less pass spontaneously
Larger stones may require surgical intervention
Extracorporeal shock wave lithotripsy
Ureteroscopic destruction or removal
Open surgical removal
Endoscopic removal of stone (PCNL)