Identify placental insufficiency early
An elevated resistance index or absent/reversed end‑diastolic flow are red flags for placental dysfunction – often appearing before growth restriction becomes apparent on biometry.
The umbilical artery is the blood vessel that carries deoxygenated blood from the fetus to the placenta. By measuring the blood flow velocity waveform in this vessel, we can assess the resistance in the placental circulation – a critical indicator of placental function. Abnormal umbilical artery Doppler findings are among the earliest signs of placental insufficiency, which can lead to fetal growth restriction (IUGR), pre‑eclampsia, and other complications.
Umbilical artery Doppler is a simple, non‑invasive test that is often part of a routine ultrasound in high‑risk pregnancies, or performed when growth concerns or maternal conditions are present. It provides objective, reproducible data that guides decisions about the frequency of monitoring, maternal therapy, and timing of delivery.
At Amytri, our umbilical artery Doppler examinations are performed by a consultant radiologist with advanced training in fetal medicine. We obtain high‑quality waveforms from the free‑floating loop of the umbilical cord, calculate the resistance index (RI) and pulsatility index (PI), and interpret the results in the context of your gestational age and clinical history. Our reports help your obstetrician make informed, evidence‑based decisions.
The placenta is the baby's lifeline – umbilical artery Doppler is the best non‑invasive way to assess how well it is working.
An elevated resistance index or absent/reversed end‑diastolic flow are red flags for placental dysfunction – often appearing before growth restriction becomes apparent on biometry.
In pregnancies with fetal growth restriction, umbilical artery Doppler is the cornerstone of surveillance. Progressive worsening (from elevated RI to absent diastolic flow) often triggers delivery to prevent hypoxic injury.
Regular monitoring with umbilical artery Doppler has been shown to reduce perinatal mortality and morbidity in high‑risk pregnancies, by enabling timely delivery and neonatal preparedness.
We obtain high‑quality waveforms and calculate indices that reflect placental resistance and fetal adaptation.
We measure the peak systolic velocity (S) and the end‑diastolic velocity (D) from the waveform. The relationship between these gives the resistance index.
RI = (S‑D)/S. A normal RI decreases with advancing gestation. An elevated RI (above the 95th percentile) indicates increased placental resistance – a sign of insufficiency.
PI = (S‑D)/mean velocity. It is another measure of resistance, often used in research and clinical practice. Elevated PI also indicates placental dysfunction.
We assess the presence, absence, or reversal of end‑diastolic flow. Absent end‑diastolic flow (AEDF) or reversed end‑diastolic flow (REDF) are severe signs of placental compromise and often prompt delivery.
We evaluate the contour of the waveform – a "notch" or abnormal shape can also indicate increased resistance, though this is less specific than RI/PI.
We combine umbilical artery Doppler with fetal biometry, amniotic fluid assessment, and other Dopplers (MCA, uterine) to form a complete picture of fetal and placental health.
Your obstetrician refers you for umbilical artery Doppler – often as part of a growth scan, or in the context of hypertension, suspected IUGR, or reduced fetal movements.
We locate a free‑floating loop of the umbilical cord and obtain a clear waveform using colour and spectral Doppler. We measure several consecutive waveforms and take the average.
We calculate RI, PI, and assess end‑diastolic flow. Results are compared to gestational age‑specific reference ranges. A normal result is reassuring; abnormal results guide further management.
We provide a detailed Doppler report and discuss the findings with you and your obstetrician. Recommendations may include increased monitoring, maternal medication, or planning for early delivery.
It is a standard part of surveillance for high‑risk pregnancies, but may also be performed for reassurance in certain situations.
These conditions impair placental perfusion – umbilical artery Doppler helps monitor and guide management.
Umbilical artery Doppler is the most important test in evaluating IUGR – it helps differentiate constitutionally small babies from those with placental insufficiency.
If you have a history of IUGR, pre‑eclampsia, or placental abruption, umbilical artery Doppler is recommended in subsequent pregnancies.
In twins, umbilical artery Doppler can identify which twin has placental insufficiency, guiding selective monitoring and delivery decisions.
Umbilical artery Doppler can provide reassurance or identify the need for intervention if fetal movements are reduced.
Beyond 41 weeks, placental function may decline – umbilical artery Doppler can help assess whether the placenta is still functioning adequately.
Umbilical artery Doppler is one of the most important tools in fetal medicine – it requires accurate technique and careful interpretation. Our consultant radiologist has extensive experience in acquiring and interpreting umbilical artery waveforms, and works closely with your obstetrician to ensure the best outcomes for you and your baby.
The umbilical artery Doppler is a focused but important test – having your partner with you provides support and shared understanding.
We encourage partners to attend the Doppler examination. We explain the waveforms and what they indicate, and answer any questions. If the results are abnormal, we discuss them sensitively and provide a clear plan for management.
It is a specialised ultrasound that measures blood flow in the umbilical artery, providing information about placental resistance and fetal oxygenation. It is a key test for monitoring high‑risk pregnancies.
Yes. It uses standard ultrasound technology with no known harmful effects. The thermal index is kept within safe limits, and it is routinely used in high‑risk pregnancies worldwide.
Normal results (low RI/PI, positive end‑diastolic flow) indicate adequate placental function. Elevated RI/PI or absent/reversed end‑diastolic flow suggest placental insufficiency, requiring closer monitoring or delivery.
Usually 10‑15 minutes. If the baby is active, it may take a bit longer to obtain a steady waveform.
Yes, typically a referral from your obstetrician is required. They will indicate the indication and whether additional Dopplers (e.g., MCA) are needed.
It depends on the reason. Some women need a single assessment, while those with IUGR or pre‑eclampsia may need weekly or more frequent monitoring to track trends.
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