Lutz and Meudt used a modification of a formula by McLean and Edell to calculate the luminal volume of the urinary bladder using ultrasonography. This can be used to estimate the residual urine volume after voiding.


urinary bladder volume in mL =

= (width in cm) * (depth in cm) * (length in cm) / 2



• The width is measured in the transverse view.

• The length and depth are measured in the longitudinal view along the sagittal midline (see Figure, page 23, Richter et al).

• The depth is the length along the dome of the bladder.

• The length is the maximal length in the sagittal midline


post-voiding volume as percent of pre-voiding volume =

= residual urine in percent =

= (urinary bladder volume in mL after voiding) / (urinary bladder volume in mL before voiding) * 100%



• The equation on page 27 of Richter et al have the two volumes reversed, with pre-voiding as the numerator and post-voiding as the denominator)


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