15) Micturition and Incontinence Flashcards
What structures of the bladder are involved in storage and micturition?
Detrusor muscle
Internal urethral sphincter (often only in males)
External urethral sphincter
At what volume do we first sense there is urine in the bladder?
150ml
Describe SNS activity on bladder in storage:
Hypogastric nerve (T10-L2) acts on beta 3 receptors in detrusor muscle to relax it
Describe SNS activity on internal urethral sphincter in storage:
Hypogastric nerve (T10-L2) acts on alpha 1 receptors in internal urethral sphincter to contract it
What does the SNS have an effect on during micturition?
Bladder and internal urethral sphincter to allow storage
What acts on external urethral sphincter during storage?
Somatic motor neurones from pudendal nerve (S2-4) act on nAChr to cause contraction
How do we know how full the bladder is?
Stretch receptors in wall which feed sensory information regarding bladder stretch back to spinal cord
What is the L centre and what does it control?
Is the pontine storage centre in the brainstem and controls storage phase of micturition:
Stimulates SNS and somatic NS
Inhibits PSNS
What does the PSNS have an effect on during micturition?
Pelvic nerve (S2-4) acts on M3 receptors to cause contraction of detrusor muscle
What stimulates the M centre and PSNS?
Afferent impulses from bladder stretch
What is the M centre and what does it control?
Pontine micturition centre in brainstem that:
Inhibits L centre -> relaxes EUS
Inhibits SNS
Stimulates PSNS
What are the M and L centre controlled by?
Cortex which can override these centres
Why can’t babies control when they micturate?
No descending neuronal modulation from brainstem, so automatic voiding when bladder reaches certain level
Where is the detrusor muscle located?
Below the submucosa and surrounded in adventitia
What are the muscle layers of the bladder and why are they important?
3: inner longitudinal, circular and outer longitudinal
Allow strength in all directions of stretch
What is the internal urethral sphincter?
Continuation of detrusor muscle at bladder neck
What is the external urethral sphincter?
Skeletal muscle derived from pelvic floor muscles
What effect does a lower motor neurone (below T12) lesion have on bladder?
Flaccid bladder - damage to parasympathetic outflow so detrusor muscle can’t contract. Bladder fills uncontrollably until overflow incontinence
What effect does a upper motor neurone (above T12) lesion have on bladder?
Reflex bladder - no afferent signals from bladder wall so no awareness of filling, micturition reflex so bladder empties as it fills. May get dyssynergia, where sphincters are poorly co-ordinated
How would you classify lower urinary tract symptoms?
Problems with storage, voiding or post micturition
How may storage problems present?
Frequency, urgency and nocturia
How may voiding problems present?
Slow stream
Hesitancy
Straining
Terminal dribble
How may post-micturition problems present?
Feeling of incomplete emptying or dribble
What is urinary incontinence?
Complaint of any involuntary leakage of urine
What is stress UI?
Involuntary leakage on effort or exertion, or on sneezing or coughing
What is urge UI?
Involuntary leakage accompanied by or immediately proceeded by urgency
What is mixed UI?
Involuntary leakage associated with urgency and exertion
What is overflow incontinence?
Retention of urine causes bladder to swell until it can’t hold anymore
What is overactive bladder syndrome?
Encompasses both MUI and UUI, and with symptoms of urgency, frequency and nocturia
What is the association of incontinence and age?
Increasing prevalence with age
What are some risk factors for incontinence?
Weakened pelvic floor muscles (child-birth, surgery) Age Obesity UTI Menopause
What examinations may you do to investigate incontinence?
BMI
Abdominal examine to exclude palpable bladder
Digital rectal examination
Stress test
What investigations may you carry out?
Urine dipstick
Freq-vol chart
Post-micturition residual volume - ultrasound
Invasive urodynamics - contrast and video
Cytoscopy - looking for cancer or stones
What general management may be recommended?
Modify fluid intake Weight loss Stop smoking Decrease caffeine Fixed schedule for voiding
What can be used if patients can’t have surgery and conservative management hasn’t worked?
Indwelling catheter
Sheath device - condom catheter
Incontinence pads
What specific management for SUI is there?
Pelvic floor muscle training - 8 contractions, 3 times a day for 3 months
Duloxetine - combined noradrenaline and serotonin uptake inhibitor, increases activity of EUS in filling, but many side effects
What surgical options can be offered for females with SUI?
Permanent intention:
Low-tension vaginal tapes - support mid-urethra
Retropubic suspension procedures - corrects position of proximal urethra
Classical sling procedures - supports urethra
Temporary intention:
Intramural bulking agents - allows urethra to resist abdominal pressure
What surgical options can be offered for males with SUI?
Artificial urinary sphincter - stimulates normal sphincter to close
Male sling procedure
What specific management for UUI is there?
Bladder training Anticholinergics (M2, M3) - oxybutynin B3 agonist - mirabegron Botulinum toxin - prevents ACh release so no detrusor muscle contraction, 3-6 months Surgery - sacral nerve neuromodulation
