1. What is Umbilical Artery Pulsatility Index?

Definition: The Pulsatility Index (PI) is a Doppler ultrasound measurement that assesses blood flow resistance in the umbilical artery during pregnancy.

Purpose: It helps evaluate fetal well-being and placental function, particularly in high-risk pregnancies.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( PI \) — Pulsatility index (dimensionless)
• \( PSV \) — Peak systolic velocity (cm/s)
• \( EDV \) — End-diastolic velocity (cm/s)
• \( MV \) — Mean velocity (cm/s)

Explanation: The difference between peak and end-diastolic velocities is divided by the mean velocity to calculate resistance to blood flow.

3. Importance of PI Measurement

Details: Abnormal PI values may indicate fetal distress, intrauterine growth restriction, or placental insufficiency.

4. Using the Calculator

Tips: Enter the PSV, EDV, and MV values obtained from Doppler ultrasound measurements. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal PI range?
A: Typically 0.6-1.2 in third trimester, but varies with gestational age.

Q2: What does a high PI indicate?
A: Increased resistance in umbilical circulation, possibly due to placental insufficiency.

Q3: What if EDV is absent?
A: This indicates very high resistance; consult a specialist immediately.

Q4: How often should PI be measured?
A: Frequency depends on risk factors, typically every 2-4 weeks in high-risk pregnancies.

Q5: Can PI predict pregnancy outcomes?
A: While informative, PI should be interpreted with other clinical findings and tests.