Dietz et al. using translabial ultrasound proposed the following formula in 2012:
Postvoid Residual Bladder Volume (ml) =
Height x Depth x 5.6Dietz H.P. et al, 2012.
It is fairly accurate, simple and thus our method of preference.
- Dietz, H.P., Velez, D., Shek, K.L. et al. Determination of postvoid residual by translabial ultrasound. Int Urogynecol J 23, 1749–1752 (2012). https://doi.org/10.1007/s00192-012-1769-0