What are the expected fetal Doppler velocimetry results in a pregnant woman with maternal hypertension?

Expected Fetal Doppler Velocimetry Results in Maternal Hypertension

In pregnancies complicated by maternal hypertension, expect abnormal umbilical artery Doppler with elevated resistance indices, potential absent or reversed end-diastolic flow in severe cases, and brain-sparing changes in the middle cerebral artery indicating fetal adaptation to placental insufficiency. 1, 2

Umbilical Artery Doppler Findings

Progressive Abnormalities in Hypertensive Disorders

• Elevated systolic/diastolic (S/D) ratio >2.6 with notching is the earliest abnormal finding, associated with 93% positive predictive value for complications including stillbirth, preterm birth, and intrauterine growth restriction (IUGR) 3

• Increased pulsatility index (PI) and resistance index (RI) reflect rising placental vascular resistance due to impaired trophoblastic invasion and defective spiral artery remodeling 2, 4

• Absent end-diastolic velocity (AEDV) indicates severe placental compromise with fetal hypoxemia, occurring in >20% of cases progressing to perinatal death 1

• Reversed end-diastolic flow (REDF) represents critical placental failure with imminent fetal decompensation, requiring delivery at 30-32 weeks 5, 6

Clinical Significance

• Abnormal umbilical artery Doppler is the most predictive marker of adverse perinatal outcomes compared to NST or biophysical profile in IUGR secondary to hypertensive disorders 1

• Management incorporating umbilical artery Doppler reduces perinatal death by 38% and decreases unnecessary interventions in high-risk pregnancies 1

Middle Cerebral Artery (MCA) Doppler Changes

Brain-Sparing Physiology

• Decreased MCA pulsatility index and resistance index indicates cerebral vasodilation as the fetus redistributes blood flow to protect vital organs 7

• MCA-RI <5th percentile demonstrates brain-sparing with 70.1% sensitivity and 64.3% specificity for predicting fetal distress at 35-40 weeks gestation 7

• Brain-sparing detected by MCA Doppler is associated with neurobehavioral impairment in survivors, making it clinically significant beyond immediate fetal status 1

Cerebroplacental Ratio (CPR)

• CPR (MCA-PI/UA-PI) <1.0 indicates pathologic redistribution and identifies fetuses at higher risk for adverse outcomes 1, 7

• Abnormal CPR combined with abnormal maternal uterine artery Doppler effectively discriminates small-for-gestational-age fetuses at risk for adverse outcomes 1

Maternal Uterine Artery Doppler Patterns

Expected Abnormalities

• Elevated PI and RI with persistent notching beyond 24 weeks indicates failed second-wave trophoblastic invasion 1

• Bilateral abnormal uterine artery waveforms in the third trimester predict adverse outcomes including cesarean delivery, IUGR, preterm delivery, and low Apgar scores 1

• Abnormal maternal uterine artery Doppler at IUGR diagnosis predicts higher risk of developing abnormal fetal brain Doppler and adverse perinatal outcomes 1

Screening Performance

• Combined maternal characteristics, fetal biometry, and uterine artery Doppler at 19-24 weeks identifies 90% of IUGR delivering <32 weeks with 10% false-positive rate 1

Ductus Venosus Doppler in Severe Cases

Advanced Compromise Indicators

• Absent or reversed A-wave reflects diastolic dysfunction and cardiac compromise, occurring late in the deterioration sequence after arterial changes 1

• Absent or reversed A-wave for >7 days predicts stillbirth with 100% sensitivity and 80% specificity 1

• Ductus venosus assessment is typically performed after umbilical artery abnormalities are detected and guides timing of delivery in preterm IUGR 1

Temporal Sequence of Doppler Deterioration

Characteristic Progression Pattern

The fetal circulatory adaptation follows a predictable sequence 1:

1. Umbilical artery abnormalities (elevated PI/RI, then AEDV, then REDF)
2. Middle cerebral artery changes (decreased PI/RI indicating brain-sparing)
3. Venous Doppler abnormalities (ductus venosus A-wave changes)
4. Biophysical profile deterioration (late finding)

Clinical Pitfall

• Doppler and biophysical profile results do not always show consistent relationships in IUGR fetuses—328 IUGR cases demonstrated discordance, requiring integration of multiple parameters for management decisions 1

Severity Stratification by Doppler Findings

Mild Hypertensive Disease

• Normal or mildly elevated umbilical artery indices with preserved end-diastolic flow
• Normal MCA Doppler without brain-sparing
• Delivery timing: 38-39 weeks if IUGR with normal Doppler 5, 6

Moderate Disease

• Decreased but present end-diastolic flow in umbilical artery
• Early brain-sparing changes in MCA
• Delivery timing: 37 weeks 5, 6

Severe Disease

• AEDV or REDF in umbilical artery
• Marked brain-sparing with very low MCA-PI
• Abnormal ductus venosus A-wave
• Delivery timing: 33-34 weeks for AEDV, 30-32 weeks for REDF 5, 6

Monitoring Frequency Based on Findings

• Normal Doppler with hypertension: Weekly umbilical artery assessment 5
• Decreased end-diastolic velocity: Weekly to twice-weekly Doppler 5
• AEDV: 2-3 times weekly due to rapid deterioration risk 5
• REDF: Hospitalization with daily cardiotocography and continuous monitoring 1, 5