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what makes up the lower urinary tract?

the bladder and urethra


how is the ower urinary tract protected?

Lower urinary tract is protected by layers of fascia
Protection from pubic rami anteriorly and the iliac wings posteriorly
Peritoneum reflects over the dome of the bladder


describe the makeup of the bladder

• Has transitional epithelium
• Then lamina propria
• Then submucosa

• Multilayered epithelium; Apical (umbrella cells)
• Functions include: Barrier, afferent signaling
Lamina propria
• Functional centre’ coordinating urothelium and Detrusor
• Blood vessels, nerve fibres, myofibroblasts
Detrusor muscle
• Smooth muscle arranged in bundles
• Functional syncytium
• Each detrusor cell- 600 microns long by 5 microns

• collagen and elastin
• Innervation of muscle: postganglionic parasym.


how is the male detrusor muscle different

thicker to work against the resistance caused by the prostate


what are bladder tight junctions involved in

play a major role in cell signalling during bladder stretching


describe normal bladder function

• Compliant Reservoir for urine storage
• Barrier function (GAG layer, tight junctions):
• Passive passage of urea, Na,K;
• Resists water passage but not truly waterproof
• Damage to urothelium plays a role in disease

• Volitional Voiding (muscular function)

• Bladder pressure remains constant despite increase in volume
• Bladder is highly compliant
• Visco-elastic properties (elastin/collagen; detrusor relaxation without change in tension)

• Bladder filling- sensors detect increase in wall tension
• Afferent neurons to dorsal horn of sacral spinal cord-
• sensory/real time data on bladder state relayed to brainstem and higher centres


describe Volitional Micturition/Voiding

• voiding is through the spino-bulbar reflex and children who have not been potty trained void through this reflex
• this can be controlled by higher centres through modulation by Pontine Micturition Centre (Barrington’s nucleus) - PONS
• further processing and relaying of signals in Onuf’s nucleus in intermediolateral S2,3,4
• feel full at 250ml and uncomfortable at 500ml
• during voiding
o coordination of
 detrusor contraction
 urethra relaxation
o if this is not coordinated it can lead to voiding difficulties

Micturition: Positive feedback loop (inhibitory controls)
Detrusor contracts  Wall tension rises  Afferent signals to PMC  Efferent signals- increase detrusor contraction


what is the role of neurotransmitters in voiding

• Excitatory neurotransmission: Cholinergic (Ach)
• Role for nitric oxide in relaxation of bladder neck/EUS
• GABA and glycine inhibitory neurons
• Bladder activity subject to facilitation and inhibition (higher centres and local reflexes)
o Facilitation = contraction of detrusor & relaxation of sphincter when bladder less than full e.g anxiety states
o Inhibition = allows postponement of voiding


what happens to bladder control in spinal injuries

• Loss of central inhibition
• Typically reflex voiding through pelvic sympathetic nerves and pudendal nerves
• The level of the spinal injury can change the clinical picture – different storage and voiding symptoms


what are we interested in, in terms of bladder control

We are interested in how often the person urinates, and how much urine the person passes at once
• Bladder responsible for STORAGE of urine
• When the bladder contains c. 300mls (and it is socially convenient) VOIDING is initiated.
• Normal voiding pattern - 300-400mls per void, 4-5 per day (<7)- depending on input
• No urgency or incontinence.
Can use a frequency/volume chart - to show if they have nocturia or frequency issues


what is a bladder diary

• Collected by patient
• 3 consecutive days
• NB - Monitors Input as well as Output
• Most informative chart
• Frequency
• Functional capacity
• Nocturia
• Also Input diary: detects Hyperhydration / Excessive intake; Effects of caffeine, EtOH; Diurnal Ingestion Patterns & Binges
• “Wet” (Urinary incontinence) episodes


what are storage LUTS (lower urinary tract symptoms)

• Urgency
• Frequency
• Nocturia
• UI


what are voiding LUTS (lower urinary tract symptoms)

• Hesitancy
• Poor flow
• Intermittency
• Terminal dribbling


describe causes of frequency and nocturia

Reflects increased urinary production or decreased storage capacity
• Polyuria: Consider DM/DI, excess fluid intake
• Decreased bladder capacity: reduced compliance, reduced functional capacity, neurogenic bladder, irritation
Nocturia: Nocturnal frequency
• Normal <2x night
• Ageing bladder, BOO, decreased compliance, dietary habits
• Effect of ageing: Renal concentrating ability decreases with age-
• increased renal blood flow at night (lying down) leads to increased urine
• production
• Risk of falls and injury 2x
Nocturnal polyuria:
• Production of more than one third of 24-hour urine output between midnight and 0800


describe poor flow, hesitancy and dribble

• Decreased force of micturition usually secondary to bladder outlet obstruction (BOO – bladder outflow obstruction, urethral stricture) - “Plumbing problem”-
• May also occur with underactive / hypocontractile bladder (eg Sp cord injury) – “Pump problem”
• Hesitancy: Delay in start of micturition
• Intermittency: Involuntary start-stop; Prostatic enlargement
• Post-void dribble: Release of small amount of urine after micturition
• Due to release of urine retained in bulbar/prostatic urethra
• Straining: Use of abdominal muscles to void (Valsalva only normally required at end of voiding)


describe incontinence

• Defined as ‘involuntary loss of urine that is a social or hygienic problem and is objectively demonstrable’
• Involuntary loss of urine associated with strong desire to void (detrusor contraction)
• Involuntary loss of urine when intra-abdominal pressure rises without detrusor contraction eg with coughing, sneezing, laughing, straining, exerting


how do we assess bladder control symptoms

• Take history
– F/V chart or Bladder diary
– Examination
• Urinalysis
• Special investigations
– IPSS (International Prostate Symptom Score)
– Flow rate & PVR (post-void residual vol)
– Urodynamics


what is the International Prostate Symptom Score (IPSS)

7 questions:
• Frequency
• Nocturia
• Weak urinary stream
• Hesitancy
• Intermittency
• Incomplete bladder emptying
• Urgency
Plus quality of life (QoL) / Bother Score question: 0 = Delighted; 6 = Terrible

• Score: 0-7 / 35: Mild symptoms
• 8-19 / 35: Moderate symptoms
20-35 / 35: Severe symptoms


describe Urodynamic Assessment

• Pressure transducers
– Bladder
– Rectum
• Pressure from bladder and rectum measured during filling and voiding
• Patient asked to cough periodically
• Subtracting rectal (abdominal) pressure from bladder = detrusor activity

During filling phase, a catheter is placed in the urethra. It has a transducer which measures the pressure and there is another in the rectum measuring abdominal pressure. The intravesicle pressure minus the abdominal pressure gives the detrusor pressure. Fluid is pumped into the bladder. The squiggles are when the patient coughs


what is unstable bladder

detrusor overactivity

urination during filling phase but coughing has no effect


what is stress incontinence

coughing causes leaks


what is BOO (bladder outflow obstruction)

• No unstable contractions during filling
• No leak whilst coughing during filling
• Very high pressure and low flow during voiding


Symptoms of outflow obstruction

• “The bladder is an unreliable witness”
• Storage symptoms may come first
• Then voiding (obstructive) symptoms
• Then decompensation of detrusor
• Residual urine, chronic retention
• Bladder failure
• Renal failure


what is the management of LUTS

• Over-active bladder – Lifestyle, anti-muscarinics (Solifenacin, Fesoterodine, Oxybutynin), selective β-3 adrenoreceptor agonist (Mirabegron), Intradetrusor Botox

• Stress Incontinence – Pelvic floor exercises, weight loss, surgery (autologous rectus abdominis sling, artificial sphincter)

• Bladder Outlet Obstruction – Medical therapies: alpha-blockers (Tamsulosin), 5ARI (Finasteride), surgery (TURP, laser prostatectomy)


what is Bartter’s syndrome

blocks 2 Cl, Na, K transporter - effects similar to loop diuretics – loss of Na, K, H2O, hypercalcuria


what is Gitelman’s syndrome

blocks Cl, Na transporter - effects like thiazide diuretics – loss of Na, K, a more modest amount of water


what is Liddel’s syndrome

hyperactive ASC - opposite effect of any diuretic, leads to volume expansion and hypertension - can treat with amiloride


what is Pseudohypoaldosteronism

inactive ASC - Na loss, K retention, high aldosterone – like amiloride diuretics - note this is high aldosterone even though it says hypo as the lack of a working ASC means the body acts as if there is little aldosterone even though the body is trying to correct by producing lots


what do inactivating mutations of aquaporins lead to

(nephrogenic) Diabetes insipidus - polyuria, polydipsia ( drinking lots)


what is Addison’s disease

destruction of adrenal glands - loss of Na, hyperkalaemia, hypovolaemia - less aldosterone -> same renal result as spironolactone