What is the recommended course of action for a fetus with absent end diastolic flow on the umbilical artery (UA)?

Management of Absent End-Diastolic Flow in Umbilical Artery

The answer is B. Cesarean Section (CS). A fetus with absent end-diastolic flow (AEDF) in the umbilical artery requires delivery, and cesarean section is the strongly preferred mode of delivery due to the severe placental insufficiency and high risk of intrapartum fetal compromise 1.

Rationale for Immediate Cesarean Delivery

Absent end-diastolic flow represents severe placental compromise with obliteration of approximately 70% of placental tertiary villi arteries, creating a high-risk situation that mandates delivery rather than expectant management or labor augmentation 1.

Why Not Amniotomy or Oxytocin?

• Amniotomy (Option A) and Oxytocin (Option C) are contraindicated because they are interventions designed to augment labor in a fetus that should not undergo the stress of labor 1
• AEDF is associated with fetal hypoxemia and represents advanced placental dysfunction that cannot tolerate the additional stress of uterine contractions 1
• Perinatal death occurs in >20% of pregnancies with AEDF, with significantly worse outcomes when vaginal delivery is attempted 1

Evidence Supporting Cesarean Section

• Absent or reversed end-diastolic flow is the most predictive Doppler finding for adverse perinatal outcomes, outperforming other antenatal tests like NST and biophysical profile 1
• Research demonstrates that perinatal mortality is twice as high with vaginal delivery compared to cesarean section in AEDF cases 2
• One study showed 19% intranatal mortality with vaginal birth versus significantly lower mortality with cesarean delivery in AEDF pregnancies 2
• Historical data reveals that fetuses with AEDF who underwent vaginal delivery had substantially higher rates of NICU admission (4.4 times higher) compared to those delivered by cesarean 2

Timing Considerations

If Preterm (Before 34 Weeks)

• Do not deliver immediately if gestational age is <34 weeks unless there are additional concerning features 3, 4
• Implement intensive surveillance: daily cardiotocography, twice-weekly umbilical artery Doppler, and twice-weekly amniotic fluid assessment 3
• Administer antenatal corticosteroids for fetal lung maturation between 24-34 weeks 3
• Give magnesium sulfate for neuroprotection if delivery planned before 32 weeks 3
• Plan delivery at 33-34 weeks gestation unless deterioration occurs earlier (abnormal biophysical profile, progression to reversed flow, or non-reassuring fetal testing) 3, 4

If Term (≥37 Weeks)

• Proceed with immediate cesarean delivery 1
• At 37 weeks with AEDF, the fetus has already exceeded the recommended delivery window of 33-34 weeks, making immediate delivery mandatory 5, 3

Critical Clinical Pitfalls to Avoid

• Never attempt labor induction or augmentation with AEDF - the fetus cannot tolerate the stress of contractions given the severe placental insufficiency 1, 2
• Do not delay delivery beyond 34 weeks in AEDF cases - this significantly increases adverse outcomes 3
• Distinguish AEDF from reversed end-diastolic flow (REDF) - REDF is even more severe (63.6% mortality in one series) and requires earlier delivery at 30-32 weeks 6, 7
• Avoid managing AEDF without specialist consultation - these cases require experienced obstetric or maternal-fetal medicine involvement 3

Pre-Delivery Management

• Ensure neonatal team is prepared for potential complications given the high-risk nature 2, 8
• Obtain cord arterial and venous pH at delivery to assess degree of fetal compromise 5
• Send placenta for histopathologic examination to guide future pregnancy management 5, 3