What is uroflowmetry?
Uroflowmetry is a simple test that measures the speed, volume and shape of a child’s urine stream while passing urine. The child passes urine into a special toilet fitted with a sensor, and the device records the flow as a graph.
What does it show?
A normal urine stream is bell-shaped: it starts quickly, peaks in the middle and ends smoothly. Altered shapes point to different problems:
- Tower-shaped: a very strong, short stream, in overactive bladder.
- Staccato: the pelvic floor muscles do not relax while passing urine.
- Interrupted: the bladder contracts weakly, and the child strains to pass urine.
- Plateau-shaped: a flat, low stream, from a narrowing in the urinary tract (meatal stenosis, urethral stricture).
Preparation
- The child should come to the test with a naturally full bladder. Drinking 1–2 glasses of water 1 hour before coming is enough.
- There is no need to make the child drink too much water, as this can change the result.
- Explain to your child that he or she will simply use the toilet as usual.
Residual urine
Right after passing urine, the urine left in the bladder is measured with ultrasound. In a healthy child, the bladder empties almost completely. A large amount of residual urine makes infections more likely.
Note for pediatricians and family doctors
For reliable uroflowmetry, the voided volume should be at least 50% of the expected bladder capacity for age [(age + 1) × 30 ml]. The curve shape (bell, tower, staccato, interrupted, plateau) is more informative than Qmax and should be confirmed with at least two measurements when possible. Residual urine is measured by ultrasound immediately after voiding; at age 4–6, a residual of more than 30 ml or 21%, and at age 7–12, more than 20 ml or 15%, is considered elevated.
What happens at the visit?
- The child passes urine into a special toilet or container fitted with a sensor.
- Then the urine left in the bladder is measured with ultrasound.
- The result is assessed together with the bladder diary and symptoms.
Frequently asked questions
My child cannot pass urine in front of the doctor. What should we do?
This is very common. The child can stay alone in the toilet, and the test can be repeated a few times. A relaxed setting improves the result.
Related topics
- Daytime wettingOveractive bladder, voiding dysfunctionCondition
- Meatal stenosisMeatal stenosis, narrowing of the urinary opening after circumcisionCondition
- Posterior urethral valvesCongenital membrane in the urethra, PUVCondition
- Constipation and the bladderBladder and bowel dysfunction (BBD)Condition
- Kidney and bladder ultrasoundUltrasound scan, sonographyTest
Sources
- Austin PF et al. The standardization of terminology of lower urinary tract function in children: update report from the ICCS. Neurourol Urodyn, 2016.
This page is for education. Decisions about your child’s treatment are made together with the doctor after an examination.