Chapter 118 USMI

Question 1

What is most common cause of inconitnence in adult bithches?

And juvenile?

Answer 1

USMI

Ectopic ureters (next most common, USMI)

Question 2

Describe the innervation to be bladder

Answer 2

Question 3

List 4 factors that contribute to urinary continence

Answer 3

• Tone in urethral smooth muscle
• Tone in striated muscle
• Natural eleasticity of urerthal wall
• Physical properties of the urethra (e.g. length, diameter, pelvic diaphragm)

Question 4

When does urinary continence occur?

Answer 4

When intravesicular pressure involuntarily exceeds that exerted by the urethral sphinters

Question 5

What type of receptors ‘innervate’ the external urethral sphinter?

Answer 5

Nicotinic cholinergic

Question 6

What might be caused for congenital USMI in cats?

Andmale dogs?

Answer 6

Abnormally short or absent urethra

Diverticula and dilations

Question 7

List 6 factors thought to contribute to the development of USMI

Answer 7

1. Urethral tone and length
   
   • USMI dogs have lower urethral pressure
   • Shorter urethras
   • Tail docking
2. Bladder neck position
   
   • Pelvic bladder
3. Body size and breed
   
   • Large and giant breeds x7 more liekly
   • Doberman, Old english and Irish setter
4. Gonadectomy
   
   • Neutering x8 increased risk (according to tobias, x2.2 according to O’neill JSAP 2017)
   • Neutering –> more collagen, less muscle
5. Hormonal status
6. Genital conformation
   
   • Vestibulovaginal stenosis? Recessed vulva? May exacerbate signs

Question 8

What 2 breeds are at risk of USMI in UK, according to tobias?

And according to O’Neill JSAP 2017

Answer 8

Tobias: Doberman + Old English Shepdog

O’Neil JSAP 2017: Irish setter (OR 8.09) and Doberman (OR 7.98)

Question 9

In O’neill JSAP 2017, what was overal rate of urinary incontinence

Answer 9

3.14%

Question 10

What should be performed in USMI work up?

Answer 10

• PE inc rectal and vaginal exam + vulva insoection
• Haem + Biochem
• Urinaysis + culture + susceptibility
• Advanced imaging to rule out other causes of incontinence

Question 11

What two drugs can be used in the medical management of USMI? How do they work?

Answer 11

• Phenylpropanolamine (Propalin) = alpha-adrenergic agonist –> increased sphinter tone
• Oestrogen (Incurin) = may improve smooth muscle tone and contractility (dont use in juvenile USMI)
• (GnRh agonist (e.g. deslorelin) also shown to temporarily restore continence in USMI bitches.

Question 12

IN general, what is cure rate with single therapy treatment (i.e. single sx therapy)

Answer 12

50%

Question 13

How are surgical treatments for USMI broadly categorised. List specific tx options for each category

Answer 13

• Increase urethral length or relocation of baldder neck
  
  • ​Colposuspension
  • Urethropexy and cystourethropexy
• Increase urethral resistance
  
  • ​Bulking agents
    
    • Teflon originally but –> peritoneal granuloma
    • Bovine cross-linked collagen. Now out of production
    • Dextranomer/hyaluronic acid co-polymer reported by Lüttman JSAP 2019 (previosuly collagen –> 71% success rate at 6 months, dextranomer/HA co-polymer –> 58% success)
  • Transpelvic urethral sling
    
    • N.B sling passed between urethra and vagina, through obrturator foramen and secured ventral midline pelvis
  • Transobtruator vaginal tape
  • Artificial urethral spincter

Question 14

What structures need to be avoided during palceemnt of colposuspension sutures?

Answer 14

External pudendal vessels

Question 15

Where are colpo sutures placed

Answer 15

Insert approx 1-1.5cm lateral from midline (avoiding external oudendal vessels), into side of vaginal (after it has been pushed cranially by insertion of finger/poole suction tip into vestibule/vagina), then back out (ideally 2 sutures each side in average sized dog)

Question 16

What is success for complete continence after colpo?

What is complication rate?

Answer 16

53-55% cure

11-15% complication

Increased frequency of urination, recurrent UTI, tenesmus, pain during defaecation

Question 17

Where are urethropexy sutures placed

Answer 17

In one side into prepubic tendon, throgh ventral urethral muscular layer and out (withouth penetrating lumen) then out other side of pre-pubic tendon (i.e. so results in closure of caudal abdo wall)

Question 18

What was cure rate of urethropexy as sole procedure

And complication rate

What was cure rate following colpo + urethropexy?

Answer 18

56% cure

21% complication (N.B. higher than colpo). Dysuria, anuria, increased frequency of urination

70% (with 10% complication rate)

Question 19

Comment on cystopexy alone for USMI

Answer 19

Contraindicated because results in detrusor instability (–> further incontinence)

Question 20

Where are urethral bulking agents injected?

Answer 20

2cm caudal to vesicourethral junction

Question 21

What material is used in transpelvic urethral sling?

Answer 21

Polyester ribbon

Question 22

Label the instruments

Answer 22

A-B, Transvaginal tape inside-out technique.

A, Depiction of the tape as it should appear after placement. The tape should maintain the O shape and is located in the distal third of the urethra just proximal to the urethral meatus.

B, Transvaginal tape inside-out instrumentation:

1. helical passers
2. polyethylene tubes
3. polypropylene tape

(Gynecare TVT Obturator System, Ethicon).

Question 23

What is complication rate after transobturator vaginal tape?

Answer 23

33% inc fistula formation

Question 24

Where is artificial urethral sphinter placed?

Answer 24

2cm caudal to bladder neck (to avoid impingement on ureters) in females

1cm caudal to prostate in males

Question 25

Briefly describe procedure for artificial urethral sphinter

Answer 25

* Caudal abdominal celiotomy that extends to the pubis. * Stay sutures are placed in the apex of the urinary bladder, and it is retracted cranially. Using Mixter right-angled forceps, a 2-cm section of urethra is isolated by careful and minimal blunt dissection. Excessive dissection is avoided to limit trauma to the blood supply of the urethra and minimize swelling. * Once the appropriate size has been determined, the selected artificial urethral sphincter is primed with fluid by inserting a catheter into the actuating tubing and instilling saline in the device to flush out any air. The vascular access port is flushed with sterile saline using a specialized Huber needle. The actuating tubing is secured onto the male adaptor of the port, and the artificial urethral sphincter is inflated to check for leaks. * The artificial urethral sphincter is then deflated and passed around the urethra in the area of dissection. The cuff is oriented so that the actuating tubing is directed cranially. The port is temporarily disconnected from the actuating tubing, and the tubing is tunneled through the caudal abdominal wall lateral to the rectus abdominis muscle. The port is reattached to the tubing, the boot cuff is advanced over the male adaptor-tubing connection to further secure the tubing to the port, and the port is sutured to the external rectus fascia with polypropylene suture. * A strand of 2-0 polypropylene suture is threaded through the eyelets of the artificial urethral sphincter and tied to itself to secure the cuff closed. The cuff is temporarily inflated by saline injection into the port, and the volume required to produce total urethral occlusion is measured and recorded for future reference in management of the case. The saline is then removed so that the cuff is fully collapsed. * The abdominal layers are closed, including reapposition of the elevated subcutaneous tissue to the external rectus sheath medial to the port. * Patients are kept in hospital until they are observed to urinate without straining. * Wait 6 weeks post-op until infalting cuff to allow revascularization of peri-urethral tissue

Question 26

How do you decide size of articicial sphincter?

Answer 26

Roughly 50% of the urethral circumference: for instance, if the circumference of the urethra measures 20 mm, a 10-mm artificial urethral sphincter is chosen. Artificial urethral sphincter implants are sized based on luminal diameter of the closed cuff; available sizes have diameters ranging from 6 mm to 16 mm and a cuff width of 11 or 14 mm. The urethral circumference is measured by using a strand of suture or Penrose drain. The artificial urethral sphincter selected should be slightly oversized to avoid obstruction of the urethra. The most commonly used sizes are 8, 10, and 12 mm, and in most dogs a cuff width of 14 mm is preferable

Question 27

Artificial sphinter shouldn't be inflated for 6 weks post op. 33-35% of dogs continent without any inflation. If inflation is necessary, how much is instilled?

Answer 27

0.05 - 0.2ml Observe patient urinating before discharge 56% cure 17% urethral obstruction and 63% uti!

Question 28

What medication is most effective for USMI in male dogs? How does response rate compare with females

Answer 28

Propalin \<50% of males respond

Question 29

List 3 reported surgical interventions for male dogs with USMI

Answer 29

Vas deferes pexy (i.e. --\> relocation of intrapelvic bladder neck) Prostatopexy to prepubic tendon Artificial urethral sphincter placement