Urinary incontenence Flashcards
what muscles and sphincters make up the bladder?
- The detrusor muscle – smooth muscle which forms the body and the neck of the bladder
- The internal urethral sphincter (IUS)– smooth muscle at the urethrovesicular (urethra to bladder)
- junction.
- External urethral sphincter (EUS) – includes striated muscle encircling portions of the urethra distal
- to the IUS.
- Ureterovesicular junction – where the ureters meet the bladder, usually proximal to the IUS.
What nerves and muscles are involved in bladder filling?
The **sympathetic **nervous system predominates:
* Positive stimulus (via alpha-adrenergic fibres) causes urethral smooth muscle contraction (prevents leakage)
* Inhibition of detrusor muscle (via beta-adrenergic fibres) allows passive filling of the bladder
“The voluntary squeeze” - Voluntary input to the striated urethral musculature (EUS) is via what nerve? what does this allow for?
the pudendal nerve (spinal segments S1-3 Somatic). During the “storage” phase there is contracture of this area, and “extra” closure when needed eg when coughing or the ability to voluntarily override the need to urinate when appropriate.
What nerves and muscles are involved in urination?
How does urination occur?
The parasympathetic nervous system dominates:
* When threshold is reached, stretch receptors in the bladder wall stimulate detrusor muscle contraction = detrusor reflex
* Urethral sphincter muscles relax
* Micturition reflex = detrusor reflex and inhibition of sympathetic and somatic stimulation to bladder and ureters
What are the three types of incontinece and the definitions?
True urinary incontinence: the patient is unaware that they are leaking urine.
Usually due to poor sphincter functionality. (Uncommon in cats)
Urge incontinence: the patient is aware that they need to urinate but may have lack of control. Can be caused by bladder irritation or seen as inappropriate urination
Overflow incontinence: the patient is (usually) unaware that they are urinating, occurs when urine pressure within the bladder is greater than the urethra. Considered a ‘voiding’ rather than storage disorder.
What are the two general reasons for incontinence?
- Neurogenic
- Non-neurogenic (anatomical or unctional disorder)
What are the problems and presentig signs of Cerebral lesions causing incontinence?
Problem - Rare, loss of voluntary control.
Present - The bladder can empty normally but often at inappropriate times
What are the problems and presentig signs of Brainstem-L7 lesions causing incontinence?
Problem:
- Upper motor neurone bladder
- “Autonomic bladder”
- Damage to the brain or higher spinal cord
Present:
- Absent voluntary micturition
- Bladder is hard to express
- Increased urethral sphincter tone
- High volume urinary retention
- Development of automatic bladder*
What are the problems and presentig signs of S1-S3 or nerve root lesions causing incontinence?
Problem:
- Lower motor neurone bladder
- “Paralytic bladder”
- Damage to the sacral spine/pelvic plexus/tail pull injury in cats
Present:
- Absent voluntary micturition
- Bladder is atonic, flaccid and easy to express
- Concurrent reduced perineal reflex and anal tone, may have tail paralysis
- Atonic urethral sphincters
- Absent detrusor reflex
- Can result in overflow incontinence when full
what is an Automatic bladder?
may develop over time when initial shock has passed. Where sympathetic and parasympathetic pathways enable bladder emptying reflex when threshold is reached. Not under voluntary control.
what is the most common non-neurogenic cause of canine incontinence?
How does it present?
What can it be made worse by?
Waht are the breed predispositiions?
What is the most common presentation/signalment?
Urethral Sphincter Mechanism Incompetence (USMI)
- Normally presents as intermittent involuntary leaking of urine when dog is relaxed (sleeping) or excited
- Can occur concurrently with ectopic ureters
- Patient may have good/bad leaking days
- May be congenital (less common, and some may resolve post 1-2 seasons)
- Can be exacerbated by intrapelvic bladder position
- Uncommon presentation: male entire or castrated dogs
- Breed predispositions: Irish setter, Doberman, bearded collie, rough collie and Dalmatian (O’Neill et al 2017*)
Most common presentation:
* Female
* Spayed
* Older
* Large breed
* Overweight
What is the medical management of Urethral Sphincter Mechanism Incompetence (USMI)?
Sympathomimetic agents = aim to mimic the ‘storage’ of urine phase Phenylpropanolamine; propalin (vetoquinol) and urolin (dechra)
~ 75% respond well
Oestrogens = acts on oestrogen
receptors in sphincters
Estriol; Incurin (intervet) and enurace (ianssen)
- Takes longer to get a response
- Cannot use in males/entire bitches or cats
What are the surgical management options for Urethral Sphincter Mechanism Incompetence (USMI)?
Referral level surgery (to be aware of):
Colposuspension – for intrapelvic bladders. Reposition the bladder neck into the abdomen and urethra is moved between vagina and pubic brim
Urethropexy – urethra is fixed surgically in a new cranial position.
Bulking agents for submusca of urethra (collagen injections)
Urethral occluders (expandable cuffs provide external pressure to urethra)
Prostatopexy – similar to urethropexy
Intersex patients (rare)– may have combination of genital and reproductive organs resulting in different anatomy or functional problem
This is a anatomical congenital cause of incontinence.
What is the other anatomical congenital cause of incontenance?
how does this present?
what is the treatment?
Ectopic ureters
* Incontinence observed shortly after birth
* Bladder is bypassed and urine may empty into vagina or urethra
* Grossly ureter could look normal, but ‘burrows’ along bladder
* submucosa into “intra-luminal” position.
* Can occur concurrently with other abnormalities
* Secondary infection is common (including pyelonephritis)
* Treatment: surgical
*
what is the ‘other’ (non congenital) anatomical cause of incontinence?
how does this present?
what is the underlying cause?
Detrusor instability: an overactive bladder presenting as pollakiruria. Most animals have underlying cystitis, irritating the bladder lining and over stimulating the detrusor reflex. = URGE INCONTINENCE
