Which artery should be observed through Doppler ultrasound in Fetal Growth Restriction (FGR)?

Umbilical Artery Doppler is the Primary Vessel to Observe in FGR

The umbilical artery is the preferred vessel to interrogate by Doppler flow velocimetry to guide management in pregnancies complicated by suspected FGR, as it is the only vessel with Level I evidence demonstrating reduction in perinatal mortality. 1

Primary Surveillance: Umbilical Artery

• Umbilical artery Doppler should be initiated once FGR is suspected and the fetus is considered potentially viable 1
• This is the only antepartum fetal test with randomized controlled trial evidence (Level I) showing significant reduction in perinatal deaths (RR 0.71; 95% CI, 0.52-0.98), cesarean deliveries, and inductions of labor 1
• Serial umbilical artery Doppler assessment should be performed to assess for deterioration once FGR is diagnosed 1, 2

Frequency of Umbilical Artery Doppler Surveillance

• Weekly umbilical artery Doppler evaluation is recommended for severe FGR (EFW <3rd percentile) or when decreased end-diastolic velocity is present 1, 2
• Doppler assessment 2-3 times per week when umbilical artery absent end-diastolic velocity (AEDV) is detected, due to potential for rapid deterioration to reversed end-diastolic velocity (REDV) 1
• When REDV is present, heightened surveillance with cardiotocography at least 1-2 times per day is recommended 1

Other Vessels: Adjunctive Role Only

Middle Cerebral Artery - NOT Recommended for Routine Management

• Middle cerebral artery Doppler should NOT be used for routine clinical management of FGR 1
• While MCA Doppler can identify fetuses at increased risk for cesarean delivery due to abnormal fetal heart rate patterns and neonatal acidosis, it has not been evaluated in randomized trials and no specific interventions have been shown to improve outcomes based on abnormal findings 1
• The critical limitation: lack of randomized trial evidence demonstrating that MCA Doppler-guided interventions improve perinatal outcomes 1

Ductus Venosus - NOT Recommended for Routine Management

• Ductus venosus Doppler should NOT be used for routine clinical management of FGR 1
• Although abnormal ductus venosus Doppler dramatically increases stillbirth risk compared to isolated umbilical/MCA abnormalities, this alone is insufficient to recommend routine usage 1
• May be utilized by centers with specific experience in venous Doppler, but not as standard practice 1

Uterine Artery - NOT Recommended

• Uterine artery Doppler assessment should NOT be used for routine clinical management of early- or late-onset FGR 1

Clinical Algorithm for Doppler Surveillance

Once FGR is suspected:

1. Initiate umbilical artery Doppler as primary surveillance tool 1

2. Normal umbilical artery Doppler:

   • Weekly Doppler assessment can be extended to less frequent intervals 1
   • Consider delivery at 38-39 weeks for EFW 3rd-10th percentile 1, 2

3. Decreased diastolic flow (but forward flow present):

   • Weekly umbilical artery Doppler 1, 2
   • Delivery at 37 weeks of gestation 1, 2

4. Absent end-diastolic velocity (AEDV):

   • Doppler assessment 2-3 times per week 1
   • Delivery at 33-34 weeks of gestation 1
   • Administer antenatal corticosteroids 1, 2

5. Reversed end-diastolic velocity (REDV):

   • Hospitalization recommended 1
   • CTG monitoring at least 1-2 times per day 1
   • Delivery at 30-32 weeks of gestation 1
   • Administer antenatal corticosteroids 1, 2

Common Pitfalls to Avoid

• Do not rely on middle cerebral artery or ductus venosus Doppler for timing of delivery decisions - these vessels lack the evidence base that umbilical artery Doppler possesses 1
• Do not screen with Doppler in low-risk populations - umbilical artery Doppler is not recommended as a screening tool for identifying pregnancies that will develop IUGR, only for management once IUGR is suspected 1
• Ensure proper technique: Interrogate the umbilical artery at the abdominal cord insertion for optimal reproducibility, obtain waveforms in the absence of fetal breathing, and ensure uniform waveforms 1