Uroflowmetry

Norm of Uroflowmetry

Normal uroflow curve, with normal peak and normal voiding time for quantity voided.

			Rate (Q[max])
		Volume	Female	Male
Postvoid residual amount
	Normal		≤50 mL	≤50 mL
	Equivocal		100–200 mL	100–200 mL
	Abnormal		>200 mL	>200 mL
Adults
Young <45 years		≥150 mL	18 mL/second	21 mL/second
Middle 46–65 years		≥150 mL	15 mL/second	15 mL/second
Older >65 years		>150 mL	10–15 mL/second	10–15 mL/second
		1100–2000 mL/24 hr
Children
Younger <8 years		≥100 mL	10 mL/second	10 mL/second
Older 8–13 years		≥100 mL	15 mL/second	12 mL/second

 

Usage of Uroflowmetry
Part of diagnostic evaluation for voiding abnormalities (e.g., evaluating cystourethrocele, identifying postvoiding residual volumes, determining voiding speed as an indicator of obstruction).

 

Description of Uroflowmetry

Uroflowmetry involves measuring the voiding duration, amount, and rate of urine voided into a funnel with a urine flowmeter that records the above information in a graphic format. The Q[max] is the maximum number of milliliters of urine per second. A Q[max] of less than 12 mL/second is associated with a higher risk for urinary retention. This simple, noninvasive test is usually performed with other tests such as cystometry and voiding cystourethrography.

 

Professional Considerations of Uroflowmetry

Consent form NOT required.
Preparation

1. Provide a private environment for voiding.

 

Procedure

1. Several types of urine flowmeters are available. The exact procedure depends on the type of flowmeter used and should be followed according to the manufacturer's instructions and institutional protocol.
2. In general, the flowmeter is activated just before the void, as described above. The client voids while standing to avoid straining pressure effects on urine volume. The volume voided and the rate, pattern, and duration of voiding are analyzed and displayed graphically by the urine flowmeter. A uroflow curve displays the changes in the urine flow rate throughout the void.
3. Serial recordings of each void over 2–3 days may be performed to provide the most accurate evaluation of the client's urine flow patterns. This helps correct for aberrancies such as hesitancy as a result of nervousness, or single voided specimens of extremely small or large volume.
4. The client's position during each void and the amount and route of fluid intake throughout testing should be recorded.

 

Postprocedure Care

1. None.

 

Client and Family Teaching

1. Do not void for several hours before the test. Drink several glasses of water at least 1 hour before the test so that your bladder is full and you are feeling like you have to urinate.
2. When the urge to void is felt, assume a standing voiding position and perform a normal void, completely emptying the bladder urine into the funnel of the flowmeter. The void should be performed without straining and while the rest of the body is held as motionless as possible. Urinate before defecating, and do not allow stool or toilet tissue to enter the funnel.

 

Factors That Affect Results

1. The quantity of urine voided affects the flow rate. Optimal amounts for evaluation of bladder function are between 150 and 400 mL. Quantities greater than 400 mL cause deterioration of bladder detrusor muscle function.
2. Recent urethral instrumentation may cause decreased flow rates.

 

Other Data

1. None.