Cerebroplacental Ratio: Clinical Guide

Clinical guide to Cerebroplacental Ratio including calculation, interpretation, assumptions, limitations and references.

Calculates the fetal middle cerebral artery to umbilical artery pulsatility-index ratio.

Overview

Calculates the fetal middle cerebral artery to umbilical artery pulsatility-index ratio.

Clinical Significance

Lower ratios may indicate fetal circulatory redistribution; interpretation requires gestational-age centiles.

When to Use

  • Use as structured clinical decision support when the required data are available and reliable.

How It Is Calculated

  • The displayed variables are combined using the published equation, decision rule or weighted point system.

Interpretation

  • Lower ratios may indicate fetal circulatory redistribution; interpretation requires gestational-age centiles.

Worked Example

Enter verified patient data in the displayed units; MedicalC applies the published model.

Limitations

  • Risk and classification tools can be misapplied outside their validated population.
  • Missing, estimated or non-contemporaneous data may materially change the result.

Clinical Pearls

  • Document the inputs, units, date and clinical setting with the result.
  • Use serial scores only when the same instrument and measurement method are used consistently.

Common Mistakes

  • Using the tool without confirming entry criteria.
  • Using approximate or incorrectly converted values.
  • Treating a prognostic score as a standalone treatment decision.

Frequently Asked Questions

What does this tool calculate?

Calculates the fetal middle cerebral artery to umbilical artery pulsatility-index ratio.

Can this result be used alone?

No. Interpret it with the full clinical assessment, applicable entry criteria and current guidance.

References

  1. Gramellini D et al. Obstet Gynecol. 1992;79:416-420. — Primary or supporting reference for the implemented model.

Reviewed by: MedicalC Clinical Editorial Team
Last reviewed: July 2026

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