Urinary Tract Obstruction Flashcards Preview

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Flashcards in Urinary Tract Obstruction Deck (32)
1

Causes of upper urinary tract causes?

Vaginouretral fistula d/t ligature of the ureter at spaying

2

Causes of intra urethral obstruction?

- tumour
- granulomatous inflammation
- prostatitis
- calculi
- foreign bodies

3

Extra urethral causes of obstruction?

- bladder/pelvis masses
- prostatic dz
- trauma (penile, pelvic, iatrogenic with perineal rupture repair, TPO)

4

Causes of bladder displacement

- retroflexion with perineal rupture
- displacement (abdo wall rupture/pelvic fractures)
- bladder torsion (often 2* to surgery not replacing)

5

Neurogenic causes of urine retention? LOOK UP

> LMN
- flaccid, over distended, easy to express, urine leakage
- sacral nerves affected (anywhere L5 caud jally)
- may be congenital (Manx cats)
- lumbosacral dz, cauda equina syndrome, vertebral fx
> UMN
- more common
- firm, tense bladder
- lesions cranial to sacral nerve segmented
- intervertebral disk dz, tumours, luxations, fx
> functional urethral obstruction (reflex dysynergia)
- more common dogs
- no relaxation of urethra
- hard to Tx

6

Which animals most commonly affected with urethral obstruction?

- males
- just caudal to os penis or any bend
- penile urethra in cats

7

General history Clinical signs of urethral obstruction

- dependant if obstruction complete or partial, acute or chronic, underlying cause
- inability or difficulty passing urine
- may be mistaken for constipation
- vulval/penile bleeding, Haematuria, V+
- collapse

8

PE findings with urethral obstruction

> full bladder
- beware rupture may feel like no bladder!
> inability to pass catheter
- can give false results, just because you can get in doesn't mean there is no blockage
> poss mass on palp of pelvic region
- abdo pain, depression, unproductive straining and abdo distension

9

pathophysiology of obstruction

- changes similar regardless of underlying cause
- urethral -> bladder, kidney effects, 2* systemic effects
- upper tract less life threatening unless both kidneys affected
- can be lethal

10

How does obstructive uropathy affect kidney function

- ^ ureteral and tubular pressure -> bowmans space
- GFR falls
- v renal blood flow maintains low GFR
> ischaemia nephropathy may result in permenant nephron loss

11

Is azotaemia d/t urethral obstruction reversible?

Yes!! No matter how severe

12

Will a bladder be able to acutely distend to the rib cage?

No only chronic (will rupture if acute)

13

What Effects can obstruction have on bladder ?

> overdistension
- dependnt on rate of urine production, bladder capacity and compliance
- ^ intravesical pressure prevents ureteral emptying -> ureteral reflux
- ischaemia, oedema, haemorhage and mucosal sloughing may occour

14

Systemic effects of obstruction. Reversible?

> hypovolaemia, hypotension
> biochem
- azotaemia
- acidaemia
- hyperohosphataemia
- hypocalceamia (phosphate ^ binds free ca)
- hyperkalaemia
> all reversible

15

How is hyperkalaemia seen on ECG?

- prolonged pR interval
- tall or peaked T waves
-brady cardia
- ventricular arrythmias

16

How do hyperkalaemic ECG traces differ in cats and dogs?

- cats more wide and bizarre almost like VPC but will not be tachycardic

17

What Is the most life threatening bit of obstruction?

Hyperkalaemia and hypovolaemia.
- CNS depression, vomiting, anorexia

18

How can hyperkalaemia be identified and managed?

- HR ( place IV catheter for IVFT
- before sedating etc. (Tx hypovolaemia don't worry about rupture atm!)
- dilutes potassium
- calcium gluconate IV (stabilises myocardium to counteract potassium)
> cystocentesis to alleviate blockage
- risk of leakage of urine into abdo, potential per acute septic peritonitis if have a UTI
- empty completely
- don't put off GA
- prophylactic Abx
- allows stabilisation temporarily
- buys time to call in back up
- in cats risk of UTI very low

19

When shouldn you relieve the obstruction and empty the HR bladder?

Only when stable
- needs GA or sedation unless moribund

20

What should be remembered when passing a catheter in a male cat

- kink in the urethra
- pull penis caudally and dorsal lay to straighten
- stay suture or tissue forceps
- don't push catheter, float the catheter into bladder
- lube, penile massage, flushing for clots, generally avoid stylet
- avoid Walpoles solution (v caustic for bladder and damage to urethral)

21

What needs to be done after unblocking

- save urine/plug for analysis (better if taken from cysto otherwise diluted with saline)
- bladder lovage with warm saline (until urine clear)
- when removing catheter express bladder and evaluate urine stream (urethral spasm can block)
-> if required place Indwelling catheter and closed collection system
- not always necessary, not well tolerated, may worsen urethral spasm

22

Should Abx be given prophylactically when they have a catheter in?

NO will not stop UTI but will make bacteria growing there resistant

23

What occours naturally following obstruction?

> post obstructive diuresis
- match fluid ins and outs
- (osmotic effect of retained solutes and damage to tubular feels)
> hypokalaemia poss
- check electrolytes
- supplements IV FLUIDS
- oral in food

24

What should be monitored for after obstruction

- UTIs
- Detrusor atony d/t excessive distension
- bladder outflow obstruction d/t bloodclot or sloughed mucosa
-stricture formation

25

What pharmacological agents may help post-obstruction

- Smooth muscle relaxants
> a adrenergic blockers
- phenoxybenzamine
- prazosin
> skeletal muslce relaxants
- dantrolene
- diazepam

26

What further investigation may need to be done post-obstruction clearance?

- not always done in first instance (may be better to r/o lesion)
- plain and contrast rads
- ultra sound and endoscopy

27

How can urinary tract obstruction be managed?

> surgery
- removing obstruction (urethrotomy, cystotomy)
- urinary diversion (cystotomy tube min 1w, can be permenant /scrotal/perineal urethrostomy / vaginitis-urethroplasty)
- re-establish urethral patency (end to end anastomoses in pelvic urethra for trauma or neoplasia)
> minimally invasive techniques/flushing
- retrograde hydropulsion
> medical or conservative management
> cutting edge technologies

28

Is urethrotomy a good procedure?

No better to flush into bladder and do a cystotomy

29

Eg. of cutting edge techniques for obstructions

> urethral stenting
- strictures and tumours
> balloon dilation
- stricture
> endoluminal lithotripsy
- calculi
> endoluminal resection/ablation
- tumours/polyps

30

Which is most common upper or lower obstruction?

??-

31

Egs of ureteral surgery

- ureteronephrectomy
- ureterotomy
- ureteral anastomosis
- ureteroneocystostomy (± psoas cystopexy, ± renal descensus)
- implants (subcut ureteral bypass system, ureteral stent, nephrostomy tube

32

Surgical options for management of upper urinary tract obstruction

- nephrotomy
- pyelolithotomy