Bladder Point of Care Ultrasonography
Back-link: +Palliative Wiki+Point of care ultrasound 

 
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:
  • Does the patient have a very full bladder? (I.e. is the patient in urinary retention?)

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:
  • Bladder volume (in ml) = length across (in  cm) x depth back x height x 0.72

 

Images


Images measuring bladder volume:

Miscellaneous bladder images:

Technique

The structures to identify:
  • Bladder

The probe to use:
  • A 1-5 MHZ transducer

Technique
  • 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
 

Resources

 
Tags: #POCUS
 
Authors: #GroveGL