Late Pregnancy · Fetal Doppler
UA + DV Doppler
Umbilical artery + ductus venosus Doppler. UA tracks placental resistance (AEDF / REDF concerning). DV reflects fetal cardiac compromise (a-wave changes pre-terminal). Used in growth restriction surveillance + delivery timing. NICE / RCOG / ISUOG.
Last reviewed 2 June 2026
Umbilical artery + ductus venosus Doppler
Placental insufficiency staging
Umbilical artery (UA) Doppler
Ductus venosus (DV) Doppler — if measured
Select UA Doppler status (DV optional).
Educational tool only — not medical advice. UA Doppler progression (normal → elevated PI → AEDF → REDF) reflects worsening placental insufficiency. DV reflects cardiac response (forward a-wave → absent → reversed = decompensation). Used in FGR surveillance per ACOG PB 230, SMFM, ISUOG, RCOG GTG 31.
What does this mean?
The umbilical artery Doppler shows blood-flow resistance in the placenta. As placental vessels become obliterated by insufficiency, end-diastolic flow falls — first elevated PI, then absent end-diastolic flow (AEDF, ~70 % obliteration), then reversed (REDF, ~80–90 %). The TRUFFLE trial (Lancet 2015) defined the ductus venosus (DV) Doppler as the marker of fetal cardiac decompensation — an absent or reversed a-wave means the right atrium is struggling, and is the modern trigger for delivery in early-onset FGR before 32 wk. Compared with computerised CTG, DV Doppler-led delivery in TRUFFLE improved neurodevelopmental survival at 2 years. Cerebroplacental ratio (CPR) — MCA-PI / UA-PI — pulls in the brain-sparing response and is increasingly the single most useful late-third-trimester surveillance number. Doppler decisions are individualised by GA, EFW trajectory, maternal condition, and ANS coverage.
UA Doppler
Measures blood flow through baby’s umbilical artery. Reflects placental resistance. Parameters: PI (pulsatility index), RI (resistance index), end-diastolic flow.
Progressive abnormal findings:
- Raised PI / RI.
- Absent end-diastolic flow (AEDF).
- Reversed end-diastolic flow (REDF) — pre-terminal.
DV Doppler
Ductus venosus — major fetal vessel directing oxygenated blood toward heart. Three components: S, D, A (atrial contraction).
- Normal: A-wave positive (forward flow).
- Abnormal: reduced A-wave → absent → reversed (very late, cardiac decompensation).
Delivery timing by Doppler
- >37 wk + AEDF: induction.
- >37 wk + REDF: immediate delivery.
- 34-37 wk + AEDF: delivery after consultant review.
- 34-37 wk + REDF: delivery soon.
- 28-34 wk + AEDF: steroids; deliver within days.
- 28-34 wk + REDF: deliver within 48h after steroids.
- <28 wk: difficult; balance very preterm risks; sometimes deliver if REDF.
Scan frequency
- Normal UA: weekly / every-2-weeks.
- Raised PI + positive end-diastolic flow: weekly.
- AEDF: 2-3x weekly or daily inpatient.
- REDF: daily inpatient.
- DV abnormal: daily; usually delivery within 24-72h.
Combined with other Dopplers
- MCA: brain-sparing detection; PSV for anaemia.
- Uterine artery: maternal side; high resistance + notch = PE / IUGR risk.
- CPR: MCA-PI ÷ UA-PI; sensitive for late-onset growth restriction.
Hospital admission
- Normal / mildly raised PI: outpatient.
- AEDF: usually admission for daily monitoring.
- REDF: admission.
- DV abnormal: admission.
Long inpatient stays emotionally difficult — mental health support available.
Neonatal team preparation
- Anticipate preterm delivery.
- Low birth weight.
- Possible needs resuscitation.
- Hypoglycaemia, hypothermia, jaundice monitoring.
- Possible respiratory distress.
- NICU brief / extended stay.
Future pregnancies
- If PE-related: aspirin from <16 wk + close monitoring.
- Optimise maternal disease pre-pregnancy.
- Idiopathic IUGR: surveillance + serial scanning next time.
- Thrombophilia / APS workup if recurrent.
Different scenarios
Scenario 1: 30 wk EFW <3rd centile + AEDF
Admit; steroids; daily monitoring; deliver within days. Magnesium <32 wk.
Scenario 2: 36 wk IUGR + raised PI but positive flow
Twice-weekly monitoring; deliver 37-38 wk if otherwise stable.
Scenario 3: 26 wk REDF + abnormal DV
Difficult decision; specialist counselling about outcomes. Often deliver if maternal/fetal stability allows.
Scenario 4: 33 wk + REDF
Steroids. Deliver within 48h. Likely C-section. NICU prep.
Scenario 5: Stable IUGR + normal Dopplers + good growth velocity
Outpatient surveillance. Plan delivery 37-38 wk. Reassuring.
Care guidance — UA + DV Doppler
- For high-risk pregnancies; not routine.
- AEDF / REDF triggers urgent management.
- DV changes late + critical.
- Steroids if preterm anticipated.
- Magnesium <32 wk.
- Combine with EFW, fluid, BPP, CTG.
- Mental health support for long admissions.
- Future pregnancies: preconception planning.
Sources
- RCOG Green-top Guideline 31. SGA management.
- ISUOG Practice Guidelines. Doppler ultrasonography in obstetrics.
- NICE NG137. Twin and triplet pregnancy.
- TRUFFLE Trial. Lancet 2015 — DV-based delivery timing.
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Frequently asked questions
What is umbilical artery (UA) Doppler?
ULTRASOUND measurement of BLOOD FLOW through baby's umbilical cord artery. REFLECTS placental resistance — narrowed/diseased placenta = harder for baby's heart to push blood through = high RESISTANCE. PARAMETERS: pulsatility index (PI), resistance index (RI), end-diastolic flow. NORMAL: positive end-diastolic flow throughout cycle. ABNORMAL findings progressive: RAISED PI/RI → ABSENT END-DIASTOLIC FLOW (AEDF) → REVERSED END-DIASTOLIC FLOW (REDF — pre-terminal). Used in growth restriction monitoring.
What is ductus venosus (DV) Doppler?
DUCTUS VENOSUS — major fetal vessel directing oxygenated blood from placenta toward heart. DOPPLER waveform shows THREE COMPONENTS: S (systolic, upstroke), D (diastolic, late), A (atrial contraction). NORMAL: A-WAVE positive (flowing forward toward heart). ABNORMAL progression: REDUCED A-wave → ABSENT A-wave → REVERSED A-wave (very late finding — fetal cardiac decompensation). USED in: severe growth restriction; planning delivery in extreme preterm; twin pregnancy surveillance.
What does AEDF / REDF mean?
(1) ABSENT END-DIASTOLIC FLOW (AEDF): no blood flow during DIASTOLE (between beats) in UA. SIGNALS significant placental dysfunction. (2) REVERSED END-DIASTOLIC FLOW (REDF): blood flow GOES BACKWARDS during diastole. PRE-TERMINAL finding — severe placental failure; baby decompensating. ACTION: (a) AT TERM/CLOSE-TO-TERM: immediate delivery; (b) PRETERM: antenatal steroids; close monitoring; deliver within days usually. MAGNESIUM SULPHATE if <32 wk. NEONATAL TEAM aware.
What's the relationship to growth restriction?
GROWTH RESTRICTION (IUGR / SGA): often placental insufficiency. UA Doppler tracks SEVERITY: NORMAL → high resistance → AEDF → REDF. SEQUENCE matters: late-onset IUGR (>32 wk) typically minimal UA changes but CPR drops; early-onset IUGR (<32 wk) UA changes (AEDF/REDF) prominent. DV Doppler abnormal LATE finding — gives time window before stillbirth. TIMING DELIVERY based on Doppler trajectory + maturity + biophysical profile + maternal factors.
How often are these scans done?
DEPENDS on findings: (1) NORMAL UA: weekly or every-2-weeks in surveillance. (2) RAISED PI but positive end-diastolic flow: weekly. (3) AEDF: 2-3 times weekly or daily admitted. (4) REDF: daily inpatient + delivery planning. (5) DV abnormal: daily monitoring; usually triggers delivery within 24-72 hours. INTENSITY scales with severity. EVERY case individualised by fetal medicine specialist.
What's normal UA Doppler?
NORMAL PI/RI for gestational age (centiles published). FOR PI: <95th centile reassuring; >95th centile concerning + closer monitoring; AEDF significant abnormality. RI similar interpretation. NORMAL waveform: smooth pulsatile pattern; positive end-diastolic flow component. CHANGES through pregnancy: PI/RI decrease as placenta matures + resistance normally falls.
When does AEDF/REDF mean delivery?
(1) AT TERM (>37 wk): AEDF — induction often offered. REDF — usually immediate delivery (C-section if not in labour). (2) 34-37 WK: AEDF — delivery after consultant review. REDF — delivery soon. (3) 28-34 WK: AEDF — antenatal steroids; deliver within days. REDF — deliver within 48 hours after steroids. (4) <28 WK: difficult; balance very preterm risks vs continued in-utero deterioration; sometimes deliver 24-26 wk if REDF — outcomes harsh but real. SHARED decision with parents.
What about other Dopplers?
(1) MCA (middle cerebral artery): low PI = brain-sparing; high PSV = anaemia. (2) UTERINE ARTERY: maternal vessel; high resistance + notch = PE / IUGR risk. (3) CPR = MCA-PI ÷ UA-PI: sensitive for late-onset growth restriction. (4) Aortic isthmus, hepatic veins, others less commonly used. COMBINED Doppler study gives full picture. /calculators/cpr-doppler /calculators/mca-psv for detail.
How are Dopplers done?
TRANSABDOMINAL ULTRASOUND. SPECIALIST sonographer / fetal medicine doctor. UA: free loop of cord; aim for consistent reading site. DV: at intra-abdominal portion through fetal liver; technical skill needed. NO PREP. 30-60 minutes for full study. PRINT-OUTS attached to notes. RESULTS interpreted with growth, fluid, BPP, CTG, clinical context.
Will I be admitted to hospital?
DEPENDS on findings: NORMAL or mildly raised PI: outpatient surveillance. AEDF: usually admission for daily monitoring; could outpatient with very close follow-up. REDF: admission usually. DV abnormal: admission. ADMISSION enables: daily CTG; rapid response; magnesium / steroids ready; theatre access if needed. EMOTIONALLY DIFFICULT — long inpatient stays can be very stressful.
What does my baby experience?
GROWTH RESTRICTION + reduced placental function: baby gets less oxygen + nutrients than ideal. CHRONIC adaptation: lower amniotic fluid; reduced movements; growth slows. ACUTE deterioration: cardiac stress (DV reflects); risk of stillbirth. BABY doesn't 'feel' the Doppler scan. MOVEMENT awareness still important — call if reduced movements.
What about the neonatal team?
ALERTED in advance. Anticipate: PRETERM delivery (often <34-37 wk); LOW BIRTH WEIGHT; possibly NEEDS RESUSCITATION; possible HYPOGLYCAEMIA, hypothermia, jaundice; sometimes RESPIRATORY DISTRESS even if not extremely preterm. NICU briefly likely. POSTNATAL: feeding, growth, glucose monitoring; follow-up developmental.
What's the prognosis?
DEPENDS on: (1) Severity at delivery; (2) Gestational age; (3) Underlying cause; (4) Other complications. EARLY-ONSET IUGR with REDF at <30 wk: challenging outcomes — significant disability rates. LATER-ONSET IUGR with abnormal Doppler: better outcomes; timely delivery prevents stillbirth. MAJORITY treated babies survive + most thrive. LONG-TERM: cardiovascular + metabolic monitoring later in life (programming effects).
Can I avoid this next pregnancy?
DEPENDS on cause. (1) PE-related: aspirin from <16 wk + close monitoring next pregnancy; (2) UNDERLYING maternal disease: optimise pre-pregnancy; (3) IDIOPATHIC IUGR: surveillance + serial scanning next time; (4) THROMBOPHILIA / APS workup if recurrent. PRECONCEPTION consultation with maternal-fetal medicine. NOT GUARANTEED prevention but risk reduction.
How does this relate to other calculators on BumpBites?
Companion: /calculators/cpr-doppler; /calculators/mca-psv; /calculators/fgr-doppler-composite; /calculators/biophysical-profile; /calculators/fetal-weight; /calculators/cervical-length; /calculators/antenatal-steroids; /calculators/magnesium-sulphate; /calculators/aspirin-pe-prevention.