Chapter 118 USMI Flashcards
What is most common cause of inconitnence in adult bithches?
And juvenile?
USMI
Ectopic ureters (next most common, USMI)
Describe the innervation to be bladder
List 4 factors that contribute to urinary continence
- 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)
When does urinary continence occur?
When intravesicular pressure involuntarily exceeds that exerted by the urethral sphinters
What type of receptors ‘innervate’ the external urethral sphinter?
Nicotinic cholinergic
What might be caused for congenital USMI in cats?
Andmale dogs?
Abnormally short or absent urethra
Diverticula and dilations
List 6 factors thought to contribute to the development of USMI
-
Urethral tone and length
- USMI dogs have lower urethral pressure
- Shorter urethras
- Tail docking
-
Bladder neck position
- Pelvic bladder
-
Body size and breed
- Large and giant breeds x7 more liekly
- Doberman, Old english and Irish setter
-
Gonadectomy
- Neutering x8 increased risk (according to tobias, x2.2 according to O’neill JSAP 2017)
- Neutering –> more collagen, less muscle
- Hormonal status
-
Genital conformation
- Vestibulovaginal stenosis? Recessed vulva? May exacerbate signs
What 2 breeds are at risk of USMI in UK, according to tobias?
And according to O’Neill JSAP 2017
Tobias: Doberman + Old English Shepdog
O’Neil JSAP 2017: Irish setter (OR 8.09) and Doberman (OR 7.98)
In O’neill JSAP 2017, what was overal rate of urinary incontinence
3.14%
What should be performed in USMI work up?
- PE inc rectal and vaginal exam + vulva insoection
- Haem + Biochem
- Urinaysis + culture + susceptibility
- Advanced imaging to rule out other causes of incontinence
What two drugs can be used in the medical management of USMI? How do they work?
- 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.
IN general, what is cure rate with single therapy treatment (i.e. single sx therapy)
50%
How are surgical treatments for USMI broadly categorised. List specific tx options for each category
-
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
-
Bulking agents
What structures need to be avoided during palceemnt of colposuspension sutures?
External pudendal vessels
Where are colpo sutures placed
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)
What is success for complete continence after colpo?
What is complication rate?
53-55% cure
11-15% complication
Increased frequency of urination, recurrent UTI, tenesmus, pain during defaecation
Where are urethropexy sutures placed
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)
What was cure rate of urethropexy as sole procedure
And complication rate
What was cure rate following colpo + urethropexy?
56% cure
21% complication (N.B. higher than colpo). Dysuria, anuria, increased frequency of urination
70% (with 10% complication rate)
Comment on cystopexy alone for USMI
Contraindicated because results in detrusor instability (–> further incontinence)
Where are urethral bulking agents injected?
2cm caudal to vesicourethral junction
What material is used in transpelvic urethral sling?
Polyester ribbon
Label the instruments
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:
- helical passers
- polyethylene tubes
- polypropylene tape
(Gynecare TVT Obturator System, Ethicon).
What is complication rate after transobturator vaginal tape?
33% inc fistula formation
Where is artificial urethral sphinter placed?
2cm caudal to bladder neck (to avoid impingement on ureters) in females
1cm caudal to prostate in males
Briefly describe procedure for artificial urethral sphinter
- 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
How do you decide size of articicial sphincter?
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
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?
0.05 - 0.2ml
Observe patient urinating before discharge
56% cure
17% urethral obstruction and 63% uti!
What medication is most effective for USMI in male dogs?
How does response rate compare with females
Propalin
<50% of males respond
List 3 reported surgical interventions for male dogs with USMI
Vas deferes pexy (i.e. –> relocation of intrapelvic bladder neck)
Prostatopexy to prepubic tendon
Artificial urethral sphincter placement
