What does a urine flow curve show?
One of the simplest tests in urology is a curve. What it shows, and what it does not.
A urine flow test (uroflowmetry) does not ask much of you: you pass urine into a special container or toilet. The machine measures the amount and how fast it comes out, and draws a graph of the flow over time.
What does the doctor look for?
The doctor looks at when the flow was highest and how many seconds it took to get there. The result can show whether the bladder muscle is weak or the flow is being blocked.
What does it not show?
A weak flow alone does not say where the cause lies. The prostate may have narrowed the way out, or the bladder may not have enough strength. Telling these apart sometimes takes other tests, such as measuring bladder pressure together with the flow. That is why this result is always read alongside your symptoms and examination.
Residual urine
After you pass urine, ultrasound is usually used to measure how much is left in the bladder. If 100 to 150 millilitres or more remains, the bladder is not emptying fully.
How to prepare
Most of these tests need no special preparation. You may be asked to change how much you drink, arrive with a full bladder or stop certain medicines, so ask before you go. The result is often ready straight away.