Bladder Volume Calculator

Evaluating bladder volume

Estimating bladder volume via ultrasound findings can provide useful diagnostic information in a variety of conditions affecting the lower urinary tract and to evaluate urinary bladder function.

For example, age related changes in the lower urinary tract may include decreased urinary volume and compliance. Investigation of bladder volume may be required in assessing causes of decreased urinary output.

In order to find the three dimensions of the bladder longitudinal (length), maximal transverse (width) and anterior-posterior (height), an ultrasound investigation will be required.

Ultrasounds may be performed:

• Transabdominal – using an external probe on the abdomen;
• Transvaginal – using an intra-vaginal probe;
• Transrectal – using an intra-rectal probe.

According to Liu-Ing et al. bladder volume can be computed as product of:

• Bladder Volume = Dimension 1 (Length) x Dimension 2 (Width) x Dimension 3 (Height) x Coefficient

Where the coefficient varies with bladder shape:

To the estimated bladder volume, a mean error of 12.7% is applied, according to the original study. This has been decreased from 16.9%, given the use of shape-specific coefficients in the product of the three dimensions.

Rageth and Langer proposed another method, usually employed in research:

• Bladder Volume = exp(C1 + C2 x ln(A1)+ C3 x ln(A2))

Where:

• A1 = maximal longitudinal cross-section
• A2 = maximal transverse cross-section
• C1 = 0.8304
• C2 = 0.5625
• C3 = 0.7211

References

Liu-Ing,B. et al. Bladder Shape Impact on the Accuracy of Ultrasonic Estimation of Bladder Volume'. Arch Phys Med Rehabil Vol79, 1998; pp1553-1556.

Rageth JC, Langer K. Ultrasonic assessment of residual urine volume. Urol Res. 1982; 10(2):57-60.

McLean GK, Edell SL. Determination of bladder volumes by gray scale ultrasonography. Radiology. 1978; 128(1):181-182.

Hartnell GG, Kiely EA, Williams G, Gibson RN. Real-time ultrasound measurement of bladder volume: a comparative study of three methods. Br J Radiol. 1987; 60(719):1063-1065.