Urinary flow rate

Urinary flow rate is simply the volume of urine passed in a certain time. It is usually measured electronically, for which, several types of equipment are available.

Flow rate provides useful information with the advantages of being non-invasive and relatively inexpensive.

Typical maximum values, in ml per second, would be:

• young adult (up to 55 years)
  • male 20
  • female 18
• over 55 years
  • male 12
  • female 15

The shape of the curve is also informative:

• in the normal individual, flow rate rises rapidly to a peak which is then maintained until the bladder is nearly empty
• in an individual with outflow obstruction, the curve is prolonged and the maximal flow rate reduced