cerebroplacental ratio
Pronunciation: ser-eh-bro-pla-SEN-tal
Doppler ultrasound ratio comparing fetal middle cerebral artery to umbilical artery resistance, used to detect placental insufficiency.
Full Definition
The cerebroplacental ratio (CPR) is a Doppler ultrasound parameter calculated by dividing the middle cerebral artery pulsatility index by the umbilical artery pulsatility index. This ratio reflects the balance between cerebral vasodilation and placental vascular resistance, serving as a sensitive marker of fetal compromise and placental insufficiency. A low CPR indicates brain-sparing circulation, where the fetus redistributes blood flow to protect vital organs in response to hypoxemia or growth restriction. The CPR is more sensitive than individual Doppler parameters alone for predicting adverse perinatal outcomes and is increasingly used in the management of fetal growth restriction.
Usage
Usage note: Commonly abbreviated as CPR. Should not be confused with cardiopulmonary resuscitation in obstetric contexts.
In Context
- "The cerebroplacental ratio was below the 5th percentile, suggesting fetal brain-sparing circulation." — Ultrasound report
- "Serial CPR monitoring showed progressive deterioration, prompting delivery planning." — Surveillance note