PU Doppler Ultrasound in Pregnancy 2 — Questions and Answers
Question 1: What is the cerebroplacental ratio (CPR) and why is it significant?
- MCA PI divided by UA PI; low CPR indicates brain-sparing and fetal compromise (Correct answer)
- UA PI divided by MCA PI
- MCA PI plus UA PI
- MCA velocity divided by UA velocity
Correct answer: MCA PI divided by UA PI; low CPR indicates brain-sparing and fetal compromise
The CPR is calculated as MCA PI divided by UA PI; a ratio below 1.0 indicates brain-sparing (redistribution) and is associated with adverse perinatal outcomes.
Question 2: Peak systolic velocity (PSV) in the middle cerebral artery is used to diagnose which fetal condition?
- Fetal anemia (Correct answer)
- IUGR
- Ventriculomegaly
- Placenta accreta
Correct answer: Fetal anemia
MCA PSV greater than 1.5 multiples of the median (MoM) for gestational age is the standard non-invasive method to screen for fetal anemia.
Question 3: What does reversed flow in the ductus venosus (DV) indicate?
- Severely abnormal cardiac function and imminent fetal deterioration (Correct answer)
- Normal finding in the third trimester
- Mild placental insufficiency
- Umbilical cord compression
Correct answer: Severely abnormal cardiac function and imminent fetal deterioration
Reversed or absent flow in the ductus venosus a-wave indicates elevated cardiac afterload and severe cardiac compromise, signaling imminent fetal deterioration.
Question 4: Which Doppler measurement is used in the biophysical profile scoring?
- Doppler findings are not part of the standard biophysical profile (Correct answer)
- Umbilical artery S/D ratio
- MCA peak systolic velocity
- Uterine artery PI
Correct answer: Doppler findings are not part of the standard biophysical profile
The classic biophysical profile (BPP) consists of five components including fetal breathing, movements, tone, amniotic fluid, and NST — Doppler is not a standard BPP component.
Question 5: What is a normal umbilical artery S/D ratio in the third trimester?
- Less than 3.0 (Correct answer)
- Greater than 4.0
- Less than 5.0
- Greater than 6.0
Correct answer: Less than 3.0
In the third trimester, a normal umbilical artery S/D ratio is generally less than 3.0; higher values indicate elevated placental resistance.
Question 6: What Doppler finding in the umbilical vein is associated with severe cardiac compromise?
- Pulsatile umbilical venous flow (Correct answer)
- Continuous flow
- High velocity flow
- Low velocity flow
Correct answer: Pulsatile umbilical venous flow
Pulsatile (phasic) flow in the normally continuous umbilical venous waveform indicates severe right heart failure and elevated central venous pressure in the fetus.
PU Doppler Ultrasound in Pregnancy 2
What is the cerebroplacental ratio (CPR) and why is it significant?