FE FE Hemodynamics & Blood Flow 2 — Questions and Answers
Question 1: Which Doppler waveform index is most commonly used to assess umbilical artery resistance?
- E/A ratio
- Pulsatility index (PI) (Correct answer)
- Peak systolic velocity
- Deceleration time
Correct answer: Pulsatility index (PI)
The pulsatility index (PI) is the most widely used index for assessing umbilical artery flow resistance and placental vascular impedance.
Question 2: Absent or reversed end-diastolic flow in the umbilical artery indicates:
- Normal placental function
- Mild fetal growth restriction
- Severe placental insufficiency (Correct answer)
- Polyhydramnios
Correct answer: Severe placental insufficiency
Absent or reversed end-diastolic flow in the umbilical artery signals severely elevated placental resistance and is associated with poor fetal outcome.
Question 3: Which vessel's Doppler waveform shows a characteristic 'a-wave' reflecting atrial contraction?
- Umbilical artery
- Middle cerebral artery
- Ductus venosus (Correct answer)
- Aortic isthmus
Correct answer: Ductus venosus
The ductus venosus waveform has three components: S-wave (ventricular systole), D-wave (diastole), and the a-wave (atrial contraction).
Question 4: A reversed a-wave in the ductus venosus Doppler suggests:
- Normal cardiac function
- Mild anemia
- Elevated right atrial pressure or cardiac compromise (Correct answer)
- Placental abruption
Correct answer: Elevated right atrial pressure or cardiac compromise
A reversed a-wave in the ductus venosus indicates elevated right atrial pressure, often a sign of severe cardiac compromise or heart failure.
Question 5: The 'brain-sparing' effect in a growth-restricted fetus is identified by:
- Increased middle cerebral artery PI
- Decreased middle cerebral artery PI (Correct answer)
- Increased umbilical vein PI
- Decreased ductus venosus PI
Correct answer: Decreased middle cerebral artery PI
Brain-sparing is characterized by decreased middle cerebral artery PI, reflecting vasodilation of the cerebral vessels to maintain perfusion.
Question 6: Which ratio combines umbilical artery and middle cerebral artery Doppler to assess fetal well-being?
- E/A ratio
- Cerebro-placental ratio (CPR) (Correct answer)
- Resistance index ratio
- Ductus venosus index
Correct answer: Cerebro-placental ratio (CPR)
The cerebro-placental ratio (CPR) is the MCA PI divided by the umbilical artery PI and is used to detect early redistribution in at-risk fetuses.
FE FE Hemodynamics & Blood Flow 2
Which Doppler waveform index is most commonly used to assess umbilical artery resistance?