Incontinence Flashcards
Describe detrusor muscle (structure, function)
3 layers of smooth muscle which gives strength irrespective of direction of stretch
It has stretch receptors in its wall which give rise to afferent pelvic nerves
Describe the internal urethral sphincter (structure, function)
Continuation of detrusor muscle acting as a physiological sphincter at the bladder neck
Prevents retrograde transport of ejaculate in males
Describe the external urethral sphincter (structure)
Anatomical sphincter derived from pelvic floor muscles under somatic control (skeletal muscle)
Nerve supply of detrusor muscle
Parasympathtic - pelvic nerve (S2-4) releases ACh which acts via M3 receptors causing contraction
Sympathetic - hypogastric nerve (T10-L2) releases NA which acts via B3 receptors causing relaxation
Nerve supply of IUS
Sympathetic - Hypogastric nerve (T10-L2) releases NA which acts via A1 receptors causing contraction
Nerve supply of EUS
Somatic - pudendal nerve (S2-4) from Onof’s nucleus of the ventral horn releases ACh which acts via nicotinic receptors causing contraction
Describe the storage phase of micturation
As the bladder receives urine from the ureters it distends to keep intravesical pressure constant until ~400ml
At low activity of the afferent pelvic nerve (low detrusor stretch) there is increased sympathetic stimulation so the hypogastric nerve causes detrusor relaxation and IUS contraction
The L centre of PONS stimulates the pudendal nerve to cause EUS contraction
Describe the voiding phase of micturation
At high activity of the afferent pelvic nerve (high detrusor stretch) there is increased parasympathetic and M centre stimulation.
The pelvic nerve causes detrusor contraction.
The M centre (when stimulated by cerebral cortex) stimulates parasympathetic neurones and inhibits sympathetic neurones and the L centre, leading to rhythmic detrusor contraction and relaxation of both urethral sphincters.
Describe the volume pressure graph of micturation
Pressure on y axis, Volume on X axis
Pressure is constant for first ~300ml because of detrusor relaxation and then pressure increases rapidly
As volume decreases during voiding the pressure rapidly increases and decreases with progressive decreasing peaks (rhythmic contraction)
Effects of spinal cord transection below T12
Damage to parasympathetic outflow to bladder so there is a low detrusor pressure
Bladder becomes abnormally distended with no action and overflow incontinence will occur
Effects of spinal cord transection above T12
Damage to sympathetic outflow to bladder so there is high detrusor pressure
Bladder empties frequently with little volume
Detrusor sphincter dyssynergia occurs where the detrusor muscle and EUS contract together (dramatic increase in pressure) which may result in diverticulae or urine reflux into the kidneys
Symptoms of storage problems
Frequency
Urgency
Nocturia
Symptoms of voiding problems
Slow urine stream Intermittency Hesitancy (delay before stream) Straining Terminal dribble
Symptoms of post micturation problems
Incomplete emptying
Post micturation dribble
What is urinary incontinence and what are the types
UI - any involuntary urine leakage 4 types: Stress Urge Mixed Overflow
What is stress UI
Involuntary leakage of urine on exertion, effort, coughing or sneezing
What is urge UI
Involuntary leakage of urine associated with urgency
What is mixed UI
Involuntary leakage of urine associated with urgency AND exertion, effort, coughing or sneezing
What is overflow UI
Bladder accepts too much urine with no action
Risk factors for UI
Childbirth Pelvic surgery Pelvic prolapse Increasing age (BPH in males) Anatomical abnormalities e.g ectopic urethral opening Obesity Smoking UTIs Diabetes
Examinations performed for UI
BMI
Abdominal exam (exclude palpable bladder)
DRE
Vaginal exam
What investigation are performed for UI
Urine dipstick - UTI, haematuria and glucosuria
Non invasive urodynamics - frequency volume charts and ultrasound to measure post micturation residual volume
Invasive urodynamics - pressure flow study with catheter
General management of UI
Less fluid intake Avoid diuretics and constipation Stop smoking Lose weight Voiding schedule
What options are for UI patients that can’t be managed by surgery, pharmacological or lifestyle management
Indwelling catheter
Condom catheter
Incontinence pads
Initial management for stress UI
Pelvic floor muscle training - 8 contractions 3 times a day for at least 3 months
Pharmacological option for stress UI
Duloxetine to increase tone of EUS
Not recommended due to side effects
Surgical options for females with stress UI
Permanent - low tension vaginal tapes, retropubic suspension procedures, fascial sling to support urethra
Temporary - intramural bulking agent (usually inject silicone) to improve urethra’s ability to resist increased abdominal pressure
Surgical options for males with stress UI
Artificial urethral sphincter - cuff closed around urethra which opens when need to void bladder
Fascial sling to support urethra
Initial management of urge UI
Bladder training to increase capacity - schedule for voiding for at least 6 weeks
Pharmacological options for urge UI
Anticholinergics e.g oxybutynin
B3 agonists e.g mirabegron
Injected botulinum toxin to inhibit ACh release (reversible so need every 3-6 months)
Surgical options for urge UI
Sacral nerve neuromodulation
Auto augmentation - remove bladder
Augmentation cystoplasty - increase bladder capacity
Urinary diversion
