PUBLIC LIBRARY / CALCULATOR

Prostate volume (ellipsoid)

Estimates prostate volume from the three diameters measured by ultrasound or MRI. Optionally, it also calculates PSA density.

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Check the population, units and version. The result shows the formula or classification; it does not make an automatic treatment decision.

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Method · Limits of application

Ellipsoid π/6×3 diameters/Terris–Stamey 1991; PSA density=PSA/volume

The ellipsoid formula is a geometric approximation. The cited study compared transrectal ultrasound estimates with the weight of surgical specimens and found different performance across methods and sizes. It does not automatically confirm equivalence between MRI and ultrasound or diagnosis through PSA density.

Conditions of use

Check the population, units, inclusion and exclusion criteria, and version in the original source. A result alone does not establish a diagnosis, discharge decision or prescription.

Documented parameters

Longitudinal diameter (craniocaudal) · cm
Transverse diameter (laterolateral) · cm
Anteroposterior diameter · cm
Total PSA (optional, for density) · ng/mL

3/3 reference cases checked. Numerical tests are not clinical validation.

Sources and documentation

Documented formula

Transcribed from the source or a recorded revision; this is not a clinical recommendation.

Volume (mL) = π/6 × longitudinal × transverse × anteroposterior (cm), approximately 0.52 × product of three measurements.

PSA density = PSA ÷ Volume.

References

Identifier: volume-prostatico

Original clinical content: Brazilian Portuguese.

Method version

Ellipsoid π/6×3 diameters/Terris–Stamey 1991; PSA density=PSA/volume

volume-prostatico@native-2026-10-03+df0c163d0f19

Source for the active edition

The bibliographic edition identifies the source. By itself, it proves neither full conformity of the formula nor clinical approval.

Synthetic cases checked (3)

Synthetic cases for checking the implementation, with no patient data.

Case 1

reference-001

Inputs

Longitudinal diameter (craniocaudal): 4 cm
Transverse diameter (laterolateral): 4.5 cm
Anteroposterior diameter: 3.5 cm

{
  "long": 4,
  "transv": 4.5,
  "ap": 3.5
}

Expected result

{
  "vol": 32.987
}

Actual result

{
  "vol": 32.98672286269283,
  "psad": null
}

Case 2

reference-002

Inputs

Longitudinal diameter (craniocaudal): 5 cm
Transverse diameter (laterolateral): 6 cm
Anteroposterior diameter: 5 cm
Total PSA (optional, for density): 4 ng/mL

{
  "long": 5,
  "transv": 6,
  "ap": 5,
  "psa": 4
}

Expected result

{
  "vol": 78.54,
  "psad": 0.0509
}

Actual result

{
  "vol": 78.53981633974482,
  "psad": 0.050929581789406514
}

Case 3

reference-003

Inputs

Longitudinal diameter (craniocaudal): 6 cm
Transverse diameter (laterolateral): 7 cm
Anteroposterior diameter: 6 cm

{
  "long": 6,
  "transv": 7,
  "ap": 6
}

Expected result

{
  "vol": 131.947
}

Actual result

{
  "vol": 131.94689145077132,
  "psad": null
}

Code and reproducibility

This tool’s code on GitHub

Download code and tests

Sources, version and reproduction instructions

The code tests are technical checks. Clinical approval and professional translation review are recorded separately.

Relationship with cancer research

General context — relationship to be defined

A resource for general clinical contexts. This edition does not assign a specific oncological relationship; selecting it for a study requires a justified question, population and purpose.