Author: Dr Graham Grove, 2014

The volume of urine the bladder can be determined very easily with Point of care ultrasonography. Determining this can be very relevant when you are concerned that a restless patient near the end of life is restless because of urinary retention. Thus the focussed question being asked is:

The bladder appears as an anechoic balloon in the suprapubic region. It is very easy for the human eye to tell the difference between ascites and a full bladder whereas a “bladder scanner” may misinterpret urine volume in the presence of ascites.

The bladder can be viewed initially in the transverse plane to measure the length across +/- depth back and then the sagittal plane to measure the height +/- depth back. A good approximation or urine volume for most people is:

Transverse bladder view using a Signostic RT Sagittal bladder view of the same patient. Total urine volume of about 9.4 x 11.5 x 4.3 x 0.72 = 335ml

Bladder ultrasound showing a large echogenic bladder cancer anteriorly

The structures to identify:

  • Bladder

The probe to use:

  • A 1-5 MHZ transducer


  • Place the probe in the midline directly above the pubic symphasis in the sagittal plane
  • Identify the bladder and measure the its height (z) by measuring across ways (horizontally)
  • Turn the probe 90 degrees into the transverse plane
  • Measure the length across (x) by measuring across ways (horizontally)
  • Measure the depth back (y) by measuring downwards (vertically)
  • There are various formulae the approximate the bladder volume such as the one noted above
  • bladder_point_of_care_ultrasonography.txt
  • Last modified: 2019/07/27 17:26
  • by Graham Grove