Cerebroplacental Ratio (CPR)
Cerebroplacental ratio (Gramellini 1992): MCA pulsatility index / umbilical-artery pulsatility index; < 1 indicates cerebral redistribution.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Middle-cerebral-artery pulsatility index
- 1.2
- Umbilical-artery pulsatility index
- 1.5
Result: CPR 0.8 — below 1: cerebral redistribution.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Threshold
- A CPR below 1 (or below the gestational-age centile) indicates cerebral redistribution / brain-sparing and warrants closer surveillance.
What you enter
- Middle-cerebral-artery pulsatility index (MCA-PI)
- Umbilical-artery pulsatility index (UA-PI)
How this is calculated
- Formula
- CPR = MCA-PI / UA-PI.
Gramellini D, Folli MC, Raboni S, et al. Cerebral-umbilical Doppler ratio as a predictor of adverse perinatal outcome. Obstet Gynecol. 1992;79(3):416-420. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.