Incontinence Flashcards
What is the bladder’s capacity?
600ml
Desire to void at approx 250ml
What does the process of micturition require?
The voluntary relaxation of the striated muscle around the urethra; this reduces urethral pressure
This is followed by a corresponding increase in bladder pressure as a consequence of detrusor contraction
How is the micturition cycle controlled in the brain?
The micturition cycle involves both the somatic (voluntary) and autonomic (sympathetic and parasympathetic) nervous systems
The frontal cortex provides voluntary control.
The pontine micturition centre (midbrain) co-ordinates detrusor contraction with urethral relaxation.
Bladder contraction is mediated by the parasympathetic system.
These parasympathetic fibres, along with those responsible for somatic control (pudendal nerve), originate from the sacral plexus (S2 to S4).
Excitation of the parasympathetic nerves stimulates the release of acetylcholine, which acts on muscarinic receptors (there are 5 subsets of muscarinic receptors with subset M3 being primarily responsible for bladder contraction) to cause detrusor contraction.
How is bladder filling controlled in the brain?
Bladder filling is mediated by the sympathetic system.
Sympathetic nerves arise from T11 to L2 and innervate the smooth muscle of the bladder neck and proximal urethra causing contraction, allowing the bladder to fill.
Excitation of the pudendal nerve causes contraction of the external urethral sphincter, allowing voluntary control.
Voiding therefore depends on parasympathetic activity, with opening of the bladder neck, which is involuntary, followed by voluntary relaxation of the external urethral sphincter.
A patient with advanced dementia presents with recurrent incontinence with no apparent attempt to move to the toilet before micturition. Dysfunction in which neurological centre is responsible for this presentation?
The frontal cortex
How does doxazosin affect incontinence?
It’s an alpha blocker, which blocks alpha adrenergic stimulation of the external urethral sphincter, resulting in decreased tone and consequent stress incontinence.
What should you ask during an incontinence history?
Full symptomatic history regarding LUTS
Ask specifically about pain, dysuria and haematuria, remembering that these symptoms would need urgent medical review
Bowel function and frequency
Co-morbidities and past surgeries particularly around the pelvis
Obstertric and gynaecological history
Impact on patient’s life
Smoking, alcohol, caffeine intake
What physical examinations should be carried out in someone who presents with incontinence?
Abbreviated mental test- cognition
Check dorsiflexion of the toes (S3) and perineal sensation (L1-L2), sensation of the sole (S1) and posterior aspect of the thigh (S3)- neurological
Palpate for masses or enlarged kidneys, palpate and percuss for a distended bladder. DRE should be performed in all patients to assess anal tone, presence of constipation or rectal mass and to assess prostate size in males- abdomen
Inspection may reveal vaginal atrophy or prolapse.
Pelvic floor muscle strength can be assessed during a vaginal examination- pelvis
Look for signs of chronic lung disease and CHF- cardiorespiratory
What investigations should be carried out when a patient presents with incontinence?
Frequency/volume chart- ask the patient to complete a diary over a three day period that records fluid intake, volume of urine passed and episodes of incontinence
Bloods- FBC (leucocytosis may indicate infection), U&Es, glucose (to rule out diabetes), calcium (useful to rule out hypercalcaemia which can cause constipation and confusion)
Imaging- post void bladder scan, USS abdo, CT urography, CT abdo
Urinalysis
Which are the more specialist investigations for incontinence?
Uroflowmetry- Urine flow rate and volume is measured
USS cystodynamogram- combines the flowmetry with pre and post void bladder scanning
Cystometry- measurement of bladder pressure, sensation, capacity and compliance during filling and voiding
Videourodynamics- Combination of cystometry and radiographic screening, so that both pressure and visual information is obtained.
Ambulatory urodynamics- it measures physiological filling and pressures during a patients usual daily routine
What provisional diagnoses can a flow chart show?
Frequent small volumes of urine - suggests overactive bladder
> 1/3 of the 24 hour urine is produced at night - indicative of nocturnal polyuria
> 2500 ml urine / day - indicates polyuria
What are normal uroflowmetry results?
Total voided volume > 200ml
Flow time 15-20 secs
Qmax > 20mls/sec
Smooth parabolic curve
What are the average Qmax readings in a uroflowmetry?
Males 40yrs = 22ml/sec
Females 40yrs = 25ml/sec
Males > 60yrs = 13mls/sec
Females >60yrs = 18mls/sec|
What does an overactive bladder look like on uroflowmetry?
More steep flow volume curve, resulting in decreased time to maximum flow, increased maximum flow rate and deceased maximum flow
What are the transient reversible causes of incontinence?
DIAPERS Delirium Infection Atrophy (vaginal) Pharmacological Psychological (depression + dementia) Excess urine output (diabetes) Restricted mobility Stool impaction (constipation)
