Ductus Venosus Doppler Calculator

The pulsatility index for veins, which RISES as the fetus deteriorates, read against the reference mean and standard deviation your own report prints. An absent or reversed a-wave is a categorical finding and returns no number, on purpose.

Last updated 8 Oct 2026

Ductus venosus PIV and its centile

A LATE marker, and it rises

a-wave at atrial contractionAbsent and reversed a-wave flow are CATEGORICAL findings, not index values, and selecting either returns no numbers deliberately. The arithmetic would not refuse on its own: an absent a-wave gives a finite index and a reversed one a larger one, which is why printing a number beside the finding would risk burying it. The University of Washington protocol says reversal of the A wave is always abnormal.

Peak systolic velocity, S (cm/s)The first and highest peak of the triphasic waveform, during ventricular systole. All four indices here are ratios of velocities, so they are independent of absolute calibration in a way the velocities are not.

Velocity at atrial contraction, a (cm/s)The nadir of the waveform, during atrial contraction. This is the velocity that FALLS as the fetus deteriorates, which makes the index RISE. If it is zero or negative the finding belongs in the selector above.

Time-averaged maximum velocity (cm/s)The mean of the traced maximum-velocity envelope over the cardiac cycle. It must lie between the atrial nadir and the systolic peak; outside them is a tracing error and the page returns nothing. Only the pulsatility index needs it, which is why some reports give a ductus venosus index instead.

Reference mean PIV for this gestationFrom your own report or reference table, for this gestational week. The default, 0.54, is the 30-week median in Helse Bergen’s published longitudinal ranges – an example, not a standard, and wrong for every other gestation.

Reference standard deviation of PIVAlso from your own reference. The default puts the Bergen table’s 30-week 95th centile, 0.80, at about the 95th centile here. Published tables give percentiles rather than a standard deviation, and the centile assumes a Gaussian reference, which a skewed one is not.

52.5centile against your referenceExample

S 60, a 38, time-averaged maximum 40 cm/s, forward a-wave; reference mean 0.54 and standard deviation 0.158

Four indices, three velocities, and one direction that matters

PIV = (S − a) ÷ TAMXV — the pulsatility index for veins, and it RISES with deterioration
DVI = (S − a) ÷ S · PVIV = (S − a) ÷ D · preload index = a ÷ S, which FALLS

PIV = (S − a) ÷ TAMXV: the venous pulsatility index, stated in the Journal of Perinatal Medicine as (S−A)/Tamx with S the peak ventricular systolic forward velocity, A the minimum atrial-contraction forward velocity and Tamx the time-averaged maximum velocity. It RISES as the a-wave falls
four indices, and they are not interchangeable: the literature lists (S−A)/D, (S−A)/Vmean, (S−A)/S, S/A and S/D over the same velocities. Three rise together and the preload index, a ÷ S, moves the opposite way, so a report quoting ‘the ductus venosus index’ needs to say which. PIV and DVI become IDENTICAL wherever the time-averaged maximum equals the systolic peak
absent and reversed a-wave flow: categorical findings, not extreme index values. Abnormality is a PIV at or above the 95th centile OR absent or reversed a-wave flow. SMFM defines it as decreased, absent or reversed A-wave flow, which may represent myocardial impairment and raised ventricular end-diastolic pressure
LATE, not early: the umbilical artery pulsatility index rises and the middle cerebral artery index falls first; the ductus venosus changes after both, and SMFM calls them a sign of advanced compromise. See the middle cerebral artery page and the umbilical artery page for the earlier two
why the reference comes from you: the 95th centile for PIV is a published week-by-week table and this engine cannot interpolate one. So the page takes the reference mean and standard deviation from your report and converts with the engine’s own normal distribution function

Worked example

S 60, a 38, time-averaged maximum 40 cm/s, forward a-wave; reference mean 0.54 and standard deviation 0.158
PIV = (60 − 38) ÷ 40 = 22 ÷ 40 = 0.550
z = (0.550 − 0.54) ÷ 0.158 = 0.06, so the centile is 52.5 — a shade above the reference median
Drop the a-wave from 38 to 30 cm/s: PIV rises to 0.750 and the centile to 90.8. Raise it to 39 instead and PIV falls to 0.525 and the centile to 46.2. A LOWER a-wave gives a HIGHER index, and that is the direction of deterioration
A page built with the numerator transposed would compute (38 − 60) ÷ 40 = −0.550, negative while the a-wave is forward
Select an absent or reversed a-wave and the page returns nothing: those are categorical findings, and the arithmetic would happily have printed 1.500 and 1.750 instead

The four indices at the default waveform

Published indices over three velocities, and at this waveform they give different numbers. The preload index moves the other way, because the atrial velocity is its numerator rather than a negative term. A report quoting an unqualified ductus venosus index has not said which of these it means.
Index	Definition	Value
Pulsatility index for veins	(S − a) ÷ time-averaged maximum velocity	0.550
Ductus venosus index	(S − a) ÷ S	0.367
Preload index	a ÷ S — falls where the others rise	0.633
S to a ratio	S ÷ a	1.58

Where the ductus venosus sits in the sequence

SMFM’s order, with the caveat SMFM itself gives: the sequence is variable and is mostly described in the preterm idiopathic growth-restricted fetus. Two indices fall and three rise, which is why each page in this category states its own direction rather than leaving it to be inferred.
Index	Direction with deterioration	When
Umbilical artery pulsatility index	Rises	Early
Middle cerebral artery pulsatility index	Falls — brain sparing	Early
Cerebroplacental ratio, MCA PI over UA PI	Falls	Early
Ductus venosus pulsatility index	Rises	Late — advanced compromise
Ductus venosus a-wave	Deepens, then absent, then reversed	Late
Umbilical venous pulsations	Appear	Latest

A late marker that rises, and four indices that are not the same number

The ductus venosus waveform has three phases: a systolic peak, a diastolic peak, and a nadir during atrial contraction, the a-wave. Everything useful is in the a-wave. As right-heart filling pressure rises the a-wave velocity falls, then disappears, then reverses, and the indices built over it rise, because that velocity sits in their numerator with a minus sign. Built with the numerator transposed, the index returns a negative number while the a-wave is still forward, which is the only cheap tell available: the magnitude is otherwise entirely plausible.

The timing is the other thing to hold. SMFM’s sequence puts rising umbilical artery impedance first, brain sparing second (increased umbilical and decreased middle cerebral impedance), the cerebral indices normalising third as adaptation is lost, and venous changes only then — a sign SMFM calls advanced compromise, with umbilical venous pulsations later still. So a raised ductus venosus index with normal arterial waveforms is an odd combination worth rechecking the arteries for. Within the venous changes Fratelli and colleagues describe a further order: the index rises first, then the a-wave deepens, then it reverses. Abnormality is an index at or above the 95th centile for gestation OR an absent or reversed a-wave, and those two limbs are not the same stage.

Two deliberate refusals. An absent or reversed a-wave returns no number: a zero a-wave gives a finite index of 1.500 at the default waveform and a reversed one 1.750, and printing either alongside the finding risks burying it. And the page holds no reference table. The published 95th centiles are week-by-week tables — Hecher’s, Kessler’s, the Helse Bergen ranges, whose 30-week median of 0.54 and 95th centile of 0.80 are where the defaults come from — so the page takes the reference mean and standard deviation from you and converts with the engine’s own normal distribution function. That assumes a Gaussian reference, which a percentile table need not be, and it matters most in the tails. The earlier markers are the umbilical artery and cerebroplacental ratio and the middle cerebral artery, and the growth question they serve is the consensus growth-restriction definition. This page computes a number, or applies published criteria, and names the body that publishes them. It renders no clinical decision: nothing here says whether this fetus is compromised, whether a tracing should be acted on, whether a scan should be repeated, whether labour should be induced or when a pregnancy should be delivered. An obstetric measurement is read alongside the whole clinical picture – history, gestational age, serial trend, the other biometry – and never instead of it. It supports a clinician’s judgement rather than replacing it. Thresholds here are the ones their named sources print. Reference standards differ between guidelines, a finding can cross a threshold purely by changing standard, and the cut-off your own unit works to takes precedence over anything on this page.

Frequently asked questions

Does the ductus venosus index rise or fall with deterioration?

It rises. The atrial-contraction velocity falls as right-heart filling pressure rises, and it sits in the numerator with a minus sign, so the index grows. Drop the a-wave from 38 to 30 cm/s on the default waveform and the index goes from 0.550 to 0.750. The preload index, a over S, is the one of the four that falls instead.

Is the ductus venosus an early or a late sign?

Late. SMFM’s sequence is rising umbilical artery impedance, then brain sparing with a falling middle cerebral index, then the cerebral indices normalising, and only then venous shunting, which SMFM calls a sign of advanced compromise. SMFM also notes the sequence is variable and is mostly described in the preterm idiopathic growth-restricted fetus.

Why does an absent or reversed a-wave return nothing?

Because those are categorical findings rather than extreme index values, and the arithmetic does not refuse on its own: an absent a-wave gives a finite index and a reversed one gives a larger finite index. Printing a number beside the finding risks the number being read and the finding being skipped. The University of Washington protocol says reversal of the A wave is always abnormal.

Why does the page ask for a reference mean and standard deviation?

Because the published 95th centiles are week-by-week tables this calculator cannot interpolate, and a fitted curve misclassifies at the extremes, which is the only place the answer changes anything. The defaults, 0.54 and 0.158, are tuned to the 30-week row of one published table and are wrong for every other gestation.

Which of the four indices does my report give?

You have to check, because they are different numbers. The pulsatility index for veins divides by the time-averaged maximum velocity, the ductus venosus index by the systolic peak, the peak velocity index for veins by the diastolic peak, and the preload index is the atrial velocity over the systolic peak and moves the opposite way. At the default waveform they are 0.550, 0.367 and 0.633.

Related calculators

References

Journal of Perinatal Medicine. Ductus venosus Doppler indices in fetal right heart disease, stating the venous pulsatility index as (S−A)/Tamx. 2025. doi:10.1515/jpm-2024-0577
Fratelli N, Prefumo F, Wolf H, et al. Nationwide study of ductus venosus Doppler in early fetal growth restriction. Acta Obstet Gynecol Scand. 2019.
Society for Maternal-Fetal Medicine Publications Committee (Berkley E, Chauhan SP, Abuhamad A). Doppler assessment of the fetus with intrauterine growth restriction. Am J Obstet Gynecol. 2012;206(4):300-8.
Haukeland University Hospital (Helse Bergen). Longitudinal Reference Ranges for the Pulsatility Index for Veins (PIV) of the Ductus Venosus. Bergen.
University of Washington Department of Radiology. OB Doppler Protocols, July 2025. Seattle, WA.

Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/