renology and urology - wk 4 Flashcards
describe the structure and function of the bladder wall
- Apical membrane with tight junctions
- Tight junctions important wall in cellular signalling
- As bladder fills it stretches and tight junctions send signals to further centres
- Allow control of bladder – voiding
papillary bladder tumour - type of cancer and symptoms
- Papillary bladder tumour – type of urothelial cell cancer (transitional cell cancer)
- Leads to painless visible haematuria (blood in urine)
- Bladder discomfort
- Urgency and frequency to pass urine
what are the 4 layers of the bladder wall
Urothelium
- Multi-layered epithelium
- Apical (umbrella cells)
- Functions – barrier, afferent signalling
Lamina Propria
- ‘functional centre’ coordinating urothelium and detrusor
- Blood vessels, nerve fibres, myofibroblasts
Detrusor muscle stroma
- Smooth muscle arranged in bundles
- Functional syncytium
- Each detrusor cell – 600 microns long by 5 microns
- Stroma – collagen and elastin
- Innervation of muscle – postganglionic parasymp
Adventitia/ Serosa
what are the normal bladder functions - (remember to talk about its function as a barrier)
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 – role of disease Volitional Voiding - (muscular function)
describe the bladders function as a compliant urine storage
- Bladder pressure remains constant despite increase in volume
- Bladder is highly compliant
- Visco-elastic properties (elastin/ collagen – detrusor relaxation)
- Without change in tension
how does the bladder respond to filling
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
- Higher centres control the bladder muscle further
explain why and how volitional micturition/ voiding happens
- Spino-bulbar reflex
- Modulation by pontine micturition centre (Barrington’s nucleus)
- Onuf’s nucleus in intermediolateral S2, 3, 4
Fullness at 250ml – uncomfortable at 500ml (detrusor contractions)
- Coordination of
o Detrusor muscle
o Urethral relaxation
- Relaxation of external urethral sphincter –
o Urine enters posterior urethra
describe higher control of voiding
- Involves prefrontal, hypothalamic, thalamic, cerebellar areas
- Most important is the pons – pontine level
o PMC – pontine micturition centre
o This takes afferent signals from sacral level up signal cord
o Processed by PMC
o Fires down efferent signals back to bladder – sphincter muscles
o Leading to voiding
whats the positive feedback loop involved in micturition
During voiding itself the detrusor muscle is firing a positive feedback loop
- As detrusor muscle contracts
- Wall tension in detrusor muscle rises
- Afferent signals to PMC to be processed
- Efferent signals sent out to increase detrusor contraction
what muscles and nerves are involved in voiding
- Voiding achieved by detrusor muscle contraction and sphincter muscle relaxation
o Via the pelvic nerves, pudendal nerves and Parasympathetic motor nerves
what neurotransmitters are involved in bladder control
Excitatory – cholinergic (Ach)
- Role of nitric oxide in relaxation of bladder neck/ EUS (external urethral sphincter)
Inhibitory - GABA and glycine
- Bladder activity subject to facilitation and inhibition (higher centres and local reflexes)
- Facilitation = contraction of detrusor and relaxation of sphincter when bladder less than full eg anxiety states
- Inhibition = allows postponement of voiding
how do different spinal cord injuries effect bladder control
SPINAL CORD INJURY
- Loss of central inhibition
- Typically, reflex voiding (pelvic parasympathetic nerves)
- Involves pudendal nerves
Suprapontine lesion
- Detrusor overactivity
- Urgency and frequency
Spinal (infrapontine – suprasacral) lesion
- Detrusor overactivity, detrusor-sphincter dyssynergia
- Urgency and dysfunctional voiding
- Difficulty voiding
- Don’t empty bladder to depletion
Sacral/ infrasacral lesion
- Poor intermittent urinary flow
- Hypocontractile or acontractile detrusor (underreactive)
- Urinary incompetence
what’s a normal voiding pattern
- When bladder contains 300mls (and its socially convenient) VOIDING is initiated
- Normal voiding pattern – 300-400mls per void, 4-5 per day (<7) depending on input
- No urgency or incontinence
what does a frequency chart record
- Used to figure out how troubling the patient’s urinary frequency is
- Collected by patient
- Informative
o Frequency
o Functional capacity
o Nocturia - Doesn’t give info on digested fluids by the patient
what does a bladder diary record
(INPUT AND OUTPUT CHART) – the ideal diary chart
- Collected by patient
- 3 consecutive days
- NB – monitors input as well as output
- Type of fluid eg water, caffeine, alcohol noted
- Most informative chart
o Frequency
o Functional capacity
o Nocturia
o Also input diary detects hyperhydration / excessive intake, effects of caffeine, EtOH, diurnal ingestion patterns and binges
o “Wet” (UI) episodes
storage symptoms
Storage symptoms are characterised by an altered bladder sensation
- Urgency
- Frequency
- Nocturia
- UI – urinary incontinence
voiding symptoms
- Hesitancy
- Poor flow
- Intermittency
- Terminal dribbling
what can increase urinary or decrease storage capacity (leading to freqeuncy)
- Polyuria – consider DM/DI, or excess fluid intake
- Decreased bladder capacity – reduced compliance, reduced functional capacity, neurogenic bladder, irritation (bladder stones/ tumour)
define nocturia and explain whos at risk and why
- Normal <2x night
- Ageing bladder, bladder outlet obstruction BOO, decreased compliance, dietary habits
- Effect of ageing – renal conc. Ability decreases with age
- Increased renal blood flow at night (lying down) leads to increased urine production
- Risk of falls and injury
- Patients with ankle oedema (heart problems) renal system reabsorbs fluid at night = nocturia
define nocturnal polyuria
- Production of more than 1/3rd of 24-hour urine output between midnight and 8am
what are the 2 general causes of poor flow, hesitancy and dribbling
- Decreased force of micturition usually secondary to bladder output destruction (BOO, urethral stricture) – aka ‘plumbing problem”
- May also occur with underactive/ hypocontractile bladder (eg SC injury) – aka ‘pump problem’
define hesitancy, intermittency, post-void dribbling and straining
- Hesitancy – delay in start of micturition
- Intermittency – involuntary start-stop; prostatic enlargement
- post-void dribbling ¬– release of small amount of urine after micturition
o 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)
define incontinence
‘involuntary loss of urine that is a social or hygienic problem and is objectively demonstrable’
what are the 2 types of incontinence and give a brief description
Urge incontinence (UUI) - Involuntary loss of urine associated with strong desire to void (detrusor contraction) Stress incontinence (SUI) - Involuntary loss of urine when intra-abdominal pressure rises without detrusor contraction eg with coughing, sneezing, laughing straining, exerting
how do we assess bladder symptoms
Take history
- F/ V chart or bladder diary
- Examination
o Rectal examination in men – expect prostate, and rectal turn (to check for spinal injury)
Urinalysis
Special Investigations
- IPSS (international prostate symptom score)
- Flow rate and PVR (post-void residual vol)
- Urodynamics
international prostate symptom score (IPSS), what does it consist of and what do the results imply
7 questions - Patient rates each symptoms out of 5 - Frequency - Nocturia - Urgency - Weak urinary stream - Hesitancy - Intermittency - Incomplete bladder emptying 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
UroFlowMeter - what does it measure/ assess
- Asses voided volume, maximal urinary flow rate
- Bladder scan – assess residual volume
o Over 200ml significant - Voiding time
o Prolonged voiding time = bladder output obstruction
urodynamic assessment - why, how and on who do you carry this out
- Determine underlying cause
- Indicated in patients with complex voiding patterns, suspected neurological abnormalities, young patients with severe symptoms
- Involves placement of pressure transducers in
o Bladder and rectum - Pressure from each of these measured during filling and voiding
- Patient asked to cough periodically
- Subtracting rectal (abdominal) pressure from bladder = detrusor activity
what is measured in a urodynamic assessment and how
urethral catheter is placed in the patient
o within this is the pressure transducer
o measure intravesical pressure
- Also a pressure transducer in the rectum to measure the abdominal pressure
- Intravesical pressure – abdominal pressure = detrusor pressure
- During filling phase constant rate of fluid infused into bladder – usually saline
what is seen in a normal urodynamic trace
during filling phase
- detrusor pressure kept low
- when patient coughs no urinary flow or increase in detrusor pressure
- no spontaneous rises in detrusor pressure
during voiding phase
- rise in intravesical and detrusor pressure
- normal urinary flow
what is seen in a urodynamic trace of someone with urinary incontinence - via detrusor overactivity
during filling phase
- spontaneous rises in detrusor pressure = increase urinary flow
- when patient coughs there’s no rise in detrusor pressure
during voiding phase
- rise in intravesical and detrusor pressure as normal leading to urinary flow (no evidence of blockage)
what is seen in a urodynamic trace of someone with stress incontinence
In filling phase
- when patient coughs the urinary flow increases
- detrusor pressure is constant ie compliance is normal
voiding phase is normal
what is seen in a urodynamic trace of someone with outflow obstruction
in filling phase
- no urinary leakage
During voiding phase
- flow of urine is quite low
- large rise in detrusor pressure
symptoms of outflow obstruction of the bladder - why is the “bladder and unreliable witness”
- ‘the bladder is an unreliable witness’ because symptoms that patients describe do not always determine the main underlying problems
o The storage symptoms may come first (bother the patients the most)
o Then voiding (obstructive) symptoms come later
o Then decompensation of detrusor
Residual urine, chronic retention
Bladder failure
Renal failure
management of the 3 main low urinary tract syndromes
Over-active bladder
- Lifestyle (cut back on diuretics), anti-muscarinics (solifenacin, fesoterodine, oxybutynin), selective beta-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
what are the 3 main blood markers in advanced kidney disease
- High creatinine
- High potassium
- Low bicarbonate – acidosis
what are the symptoms of advanced kidney disease
- Tired
- Itchy skin
- Short of breath – anaemic
- Cramps – low calcium
whats the definition of CKD
GFR of less than 60ml/min for >90 days/ 3 months
what are some important causes of CKD
- Diabetes/ hypertension/ glomerulonephritis/ cystic kidney disease/ renovascular disease
how do we estimate renal function
- Normal GFR – 125 ml/min/1.73m^2
- Serum creatinine clearance (24 hr urine collection)
o May be affected by age/ muscle mass/ drugs
o Urea and creatinine clearance more accurate - Isotope GFRs
o Expensive and time consuming - Formulae
o For estimated GFR (MDRD) or Creatinine clearance (cockcoft and gault) – based on creatinine
(Urine concentration x volume) / plasma concentration for CREATININE
why is serum creatinine not a good marker of renal function
- Older people have decreased muscle mass
o So creatinine can be normal even in advanced disease
the stages of CKD - what are the factors that must be met for stage 1 and 2, at what stage would you start dialysis/ transplantation
For stage 1 and 2 you must have another factor
- Biopsy proven/ radiology proven kidney disease
- Presence of polycystic kidney disease
Stage 4 – plan for dialysis
Stage 5 – plan for dialysis / transplantation
how common in CKD
- 6.2% population have CKD 3
- Given elderly population have more CKD, up to >25% of elderly pts may be expected to have stage 3 ckd 3 or worse
what are prevention strategies for CKD
- Control blood pressure (RAS inhibititors)
- Reduce proteinuria (RAS inhibition)
- If diabetes, optimise glycaemic control
- SGLT2 inhibitors (diabetes)
o CREDENCE trial – Canagliflozin
Good outcomes for renal and CV
o Dapagliflozin
o Empagliflozin
proteinuria as a cause of CKD
- In glomerulus
- All have protein in filtrate which is taken up into tubular cell and taken up into peritubular capillaries and recycled
- If we have lots of protein in blood (eg diabetes) this system is overloaded
- Leading to free radicals and cell dies
- In effort to clear away dead glomerulus fibroblasts and macrophages come and get rid of dead cell
o This allows for regeneration of new cell
o But leaves fibrosis behind
what drug is useful in proteinuria and why
ACE inhibitors are useful…
- Dilate the efferent arteriole
- Reduces glomerular pressure
- Reduces amount of proteinuria
how to safely prescribe drugs in CKD, what drugs to avoid
Avoid potential toxins
- NSAIDs/ contrast/ gentamicin
- Phosphate enemas
Drug dosing - Many drugs need to be given at a lower dose in patients with CKD o Especially chemotherapy/ antibiotics - If in doubt check BNF app - Rem - >25% of elderly pts may have CKD