Uroflowmetry is a procedure for the objective determination of bladder emptying disorders. Among other things, it determines the maximum urine flow (Qmax) and produces a urine flow curve.
Normally, the bladder holds about 300-400 ml of urine. In total, a healthy adult excretes about 1,500 ml of urine daily.
Bladder voiding dysfunction can occur in several forms:
- Pollakisuria – urge to urinate frequently without increased urination.
- Alguria – painful urination.
- Dysuria – difficult (painful) urination.
- Residual urine – incomplete emptying of the bladder.
- Urinary retention / urinary retention – bladder emptying not possible.
- Incontinence – inability to retain urine.
Indications (areas of application)
- Urinary stream attenuation
- Dysuria – painful urge to urinate with difficulty urinating.
- Prolonged urination
- Intermittent micturition – temporary cessation during urination.
- Miktionsstartstörungen – disturbances at the beginning of urination.
- Residual urine feeling
- Pollakiuria – urge to urinate frequently without increased excretion.
- Nocturia – urination at night
- Imperative urination with or without urge incontinence – sudden, uncontrollable urge to urinate with or without involuntary loss of urine.
- Incontinence – inability to retain urine.
- Reflux – backflow of urine from the urinary bladder into the ureter, possibly even into the renal pelvis.
- Urinary retention with suspected bladder emptying disorder.
- Therapy control after surgery on the urethra, prostate or drug treatment of bladder emptying disorder.
The procedure
With the help of a uroflowmeter, the outflow of urine during micturition – emptying the bladder – is recorded and graphically displayed as a urine flow curve.
The following information is recorded:
- Mean urine flow rate
- Maximum urine flow rate (Qmax)
- Urine flow time
- Micturition time (bladder emptying time)
- Flow rise time
- Total miction volume
Note: Uroflowmetry should only be assessed when the total micturition volume is > 150 ml.
To perform uroflowmetry, the bladder should be filled and there should be a sufficient urge to urinate. The bladder is then emptied into the examination device, which records the above data during micturition. The patient is alone and unobserved during bladder emptying. Subsequently, ultrasound can be used to accurately check the amount of residual urine remaining in the bladder.
The normal range for maximum urine flow is between 15 and 50 ml/s in adults.
A maximum urine flow below 10 ml/s indicates an obstruction or obstruction (occlusion). Values between 10-15 ml/s require further clarification.An altered curve progression may indicate benign prostatic hyperplasia (benign prostatic enlargement) or urethral stenosis.
By using a rectal and vesical pressure probe (in the urinary bladder and rectum), a distinction can be made between increased bladder outlet obstruction (BOO) and and hypotonic detrusor (detrusor underactivity; flaccid detrusor).