FE Hemodynamics & Blood Flow Flashcards

Which Doppler waveform index is most commonly used to assess umbilical artery resistance?

Answer: Pulsatility index (PI)

The pulsatility index (PI) is the most widely used index for assessing umbilical artery flow resistance and placental vascular impedance.

Absent or reversed end-diastolic flow in the umbilical artery indicates:

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.

Which vessel's Doppler waveform shows a characteristic 'a-wave' reflecting atrial contraction?

Answer: Ductus venosus

The ductus venosus waveform has three components: S-wave (ventricular systole), D-wave (diastole), and the a-wave (atrial contraction).

A reversed a-wave in the ductus venosus Doppler suggests:

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.

The 'brain-sparing' effect in a growth-restricted fetus is identified by:

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.

Which ratio combines umbilical artery and middle cerebral artery Doppler to assess fetal well-being?

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.