PU Doppler Ultrasound in Pregnancy 1 — Questions and Answers
Question 1: What does absent end-diastolic flow (AEDF) in the umbilical artery indicate?
- Severely elevated placental resistance with high risk of fetal compromise (Correct answer)
- Normal placental function
- Mild IUGR only
- Polyhydramnios
Correct answer: Severely elevated placental resistance with high risk of fetal compromise
Absent end-diastolic flow in the umbilical artery indicates markedly elevated placental vascular resistance and is associated with severe fetal compromise and increased perinatal mortality.
Question 2: What is the S/D ratio in umbilical artery Doppler?
- The ratio of peak systolic to end-diastolic velocity (Correct answer)
- The ratio of systolic to mean velocity
- The ratio of diastolic to systolic velocity
- The pulsatility index
Correct answer: The ratio of peak systolic to end-diastolic velocity
The S/D ratio (systolic-to-diastolic ratio) compares peak systolic velocity to end-diastolic velocity in the umbilical artery and reflects placental vascular resistance.
Question 3: Reversed end-diastolic flow (REDF) in the umbilical artery is associated with what outcome?
- Imminent fetal deterioration requiring urgent delivery consideration (Correct answer)
- Mild placental insufficiency
- Normal third-trimester finding
- Maternal hypertension only
Correct answer: Imminent fetal deterioration requiring urgent delivery consideration
REDF in the umbilical artery indicates critical placental resistance with reverse flow during diastole and is associated with very high perinatal morbidity and mortality, often requiring urgent delivery.
Question 4: Which Doppler waveform is used to assess fetal cerebral blood flow?
- Middle cerebral artery (MCA) (Correct answer)
- Anterior cerebral artery
- Posterior cerebral artery
- Circle of Willis
Correct answer: Middle cerebral artery (MCA)
The middle cerebral artery is the standard vessel used to assess fetal cerebral blood flow, particularly for detecting brain-sparing in IUGR and anemia.
Question 5: What is the brain-sparing effect in Doppler assessment?
- Increased MCA flow with decreased umbilical artery flow indicating redistribution to protect the brain (Correct answer)
- Normal MCA and UA flow
- Decreased MCA flow with normal UA flow
- Equal MCA and UA resistance
Correct answer: Increased MCA flow with decreased umbilical artery flow indicating redistribution to protect the brain
Brain-sparing refers to vasodilation of the middle cerebral artery with reduced resistance, allowing more blood to reach the fetal brain when placental insufficiency is present.
Question 6: What does an elevated pulsatility index (PI) in the uterine artery suggest in early pregnancy?
- Increased risk of preeclampsia and IUGR (Correct answer)
- Normal placental development
- Fetal anemia
- Placenta previa
Correct answer: Increased risk of preeclampsia and IUGR
An elevated uterine artery PI in the first or second trimester, especially with a diastolic notch, indicates impaired trophoblastic invasion and raises the risk of preeclampsia and IUGR.
PU Doppler Ultrasound in Pregnancy 1
What does absent end-diastolic flow (AEDF) in the umbilical artery indicate?