Uroflowmetry

What is Uroflowmetry?

Uroflowmetry is a simple, non-invasive diagnostic test that measures the speed and volume of urination. It is the first and most common test for any urinary complaints, providing a quick assessment of lower urinary tract function.

The procedure is completely painless: the patient urinates naturally into a specialized device — a uroflowmeter — which records the flow pattern (uroflowmetry curve). The test gives your doctor objective information about how your bladder and urethra are working.

When is Uroflowmetry Recommended?

Uroflowmetry is recommended for the following conditions and symptoms:

Difficulty urinating — weak stream, need to strain, intermittent urination
Frequent urination — increased frequency during day and night (nocturia)
Suspected bladder outlet obstruction (BOO) — enlarged prostate, urethral stricture, bladder neck sclerosis
Urinary incontinence — as part of a comprehensive urodynamic evaluation
Detrusor dysfunction — weak or overactive bladder muscle
Treatment follow-up — before and after medication or surgery
Detrusor-sphincter dyssynergia (DSD) — lack of coordination between the detrusor muscle and the sphincter
Screening evaluation — for any urinary complaints

Uroflowmetry is often the first step in a comprehensive urodynamic study (UDS).

How is Uroflowmetry Performed?

The test is performed in the office and takes about 10–15 minutes:

You will be asked to urinate naturally into a specialized device — a uroflowmeter, which looks like a regular toilet
Your doctor will ask you to arrive with a full bladder (drink 500–800 ml of fluid 1–2 hours before the test and avoid urinating beforehand)
You will be alone in the room during urination, ensuring complete privacy
No special preparation, catheters, or instruments are needed
Immediately after urination, the device produces a graph — the uroflowmetry curve

After urination, you may be asked to undergo an ultrasound to measure post-void residual urine volume.

What Parameters Are Measured?

The uroflowmeter records the following parameters:

Maximum flow rate (Q_max) — the highest urine flow rate, ml/s. Normal values: men under 50 — above 15 ml/s, men over 50 — above 10 ml/s; women — above 20 ml/s
Average flow rate (Q_avg) — total volume divided by voiding time, ml/s
Voided volume (V_comp) — amount of urine passed, ml. Diagnostic significance requires 150–500 ml
Voiding time (T_Q) — total duration of urination, seconds
Time to maximum flow (T_Qmax) — interval from start of urination to Q_max, seconds
Flow curve pattern — the graphical shape of the flow (curve type)

An important additional measurement is the post-void residual (PVR) urine volume, assessed by ultrasound immediately after urination. A normal PVR is less than 50–100 ml.

Types of Flow Curves

Based on the graphical shape, several curve patterns are recognized:

Normal (bell-shaped) curve — typical for healthy individuals. The flow rises rapidly to its peak and then declines smoothly
Flattened (obstructive) curve — low Q_max, prolonged voiding time. Characteristic of prostate enlargement, urethral stricture, bladder neck sclerosis
Intermittent curve — flow stops and starts. May indicate detrusor-sphincter dyssynergia or abdominal straining to void
Super-fast (funnel-shaped) curve — very high Q_max with low volume. May be seen in urinary incontinence

Advantages of Uroflowmetry

Non-invasive — no instruments or catheters required
Painless — you simply urinate naturally
Quick — the test takes only 10–15 minutes
Cost-effective — one of the most affordable urodynamic tests
Highly informative — can detect a wide range of urinary disorders
Repeatable — easy to repeat for treatment monitoring

Preparation

For accurate results, please follow these recommendations:

Drink 500–800 ml of fluid (still water, unsweetened tea) 1–2 hours before the test
Do not urinate before the procedure — your bladder should be full
Inform your doctor about any medications you are taking, especially diuretics
Avoid alcohol and caffeine on the day of the test