In a fetus with growth restriction, progressive deterioration of placental function is tracked by sequential Doppler changes. Which finding represents the most advanced stage, usually preceding an abnormal cardiotocograph and signalling imminent decompensation?
- A Raised pulsatility index of the umbilical artery
- B Reversed flow during atrial contraction in the ductus venosus ✓
- C Absent end-diastolic flow in the umbilical artery
- D Reduced end-diastolic flow in the umbilical artery
Correct answer: B. Reversed flow during atrial contraction in the ductus venosus
Explanation
The Doppler sequence in placental insufficiency progresses from raised umbilical artery impedance, through absent then reversed end-diastolic flow, to venous changes. Reversal of the ductus venosus a-wave reflects cardiac compromise and hypoxaemic myocardial dysfunction, correlates strongly with acidemia on cord sampling, and is the last Doppler abnormality before CTG deterioration, guiding timing of delivery in very preterm FGR.
Reference: Williams Obstetrics, 26th ed.
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