Tip: Ultrasound can be used to estimate bladder volume using a simple to remember formula: Height x Width x Length x 0.7
- The Width and Depth of the bladder are measured in the transverse view.
- The superior-inferior dimension (Height) is measured in the longitudinal view.
- Most ultrasound machines will automatically calculate the entire bladder volume which should be less than 300-400 mL in healthy adults and Post Void Residual (PVR) should be less than 50-100mL (Fitzgerald; Latini).
The actual formula used to calculate bladder volume is Width x Depth x Height x Correction Coefficient. If you want more accurate bladder volume measurements, you can use the correction coefficient that most closely corresponds to the patient’s bladder shape.
The table below shows you the correction coefficient for each of the bladder shapes:
| Bladder Shape | Correction Coefficient |
| Unknown | 0.72 (most commonly used) |
| Triangular prism | 0.66 |
| Cylinder (Ellipsoid) | 0.81 |
| Cuboid | 0.89 |
| Spherical | 0.52 |
