Ductus venosus

1. Ductus venosus

2. Quick hint on Fetal Circulation

3. What is a shunt ??
• A passage or anastomosis between two natural
channels, especially between blood vessels
• to turn to one side; to divert; to bypass.
• There are three shunts in the fetal circulation :
• 1- Ductus venosus
• 2- Foramen Ovale
• 3- Ductus arteriousus

5. The umbilical cord
Two umbilical arteries:
return non-oxygenated blood, fetal waste,
CO2 to placenta.
One umbilical vein:
brings oxygenated blood and nutrients to
the fetus
N.B: the nomenclature of artery or vein is in relation
to the fetal heart

7. The Journey
• Oxygen-rich blood is carried by
the umbilical vein from the
placenta to the fetus. The
umbilical vein enters at the
umbilicus and divides into two
branches:

8. • Right umbilical branch enters
through the inferior border of the
liver passes to the right side of
the liver and is joined by the
portal vein; the blood from the
liver eventually drains into
the inferior vena cava(IVC) via
the hepatic veins

9. •Left umbilical
branch gets shunted
via the ductus
venosus into the IVC
(the first shunt)

11. Ductus Venosus

12. Historical point of view
• It s attributed to Guilio Cezare Aranzi (1530-
1589), but the first written account dates back
to his contemporary Veaslius in 1561.
• Its function was long recognized but of hardly
any clinical importance until the ultrasound
techniques were introduced.

13. Anatomy and development
• It is a thin , slightly trumpet-shaped
connecting the umbilical vein to the IVC.
• Its inlet, the isthmus, is on average 0.7mm at
18 weeks and 1.7mm at 40 weeks of
gestation.
• Leaves the umbilical vein in a cranial and
dorsal direction and reaches the IVC at the
level of hepatic venous confluence

14. • Shortly below the artia
• This segment of the IVC is shaped as a funnel
bulging predominantly to the left side to
receive the Ductus venosus and the left
hepatic veins.

15. Physiologic background

16. Via Sinistra
• a classical widely accepted concept of the
pathway of the oxygenated blood to the left
side of the fetal heart. (other concept is Via
dextra)
• As a direct connection between the Umbilical
Vein and the central venous system , it has the
capacity to shunt oxygenated blood to the CVS
and thus to the left atrium

17. • During experimental hypoxia and
hypovolemia , a flow across the ductus
venosus is maintained .
• However since the flow to the liver is reduced
, this implies that the fraction of blood
shunted through ductus can increase as high
as 70 %
• A similar effect has been recorded in growth
restricted fetuses
• Alpha adrenergic constriction and beta
cholinergic relaxation has been recorded in
the ductus.

18. Umbilical liver perfusion
• About 70 to 80% of the blood in the U.V
perfuses the liver as a primary fetal organ.
• The pattern implies the importance of the
fetal liver in intrauterine life .
• Recent studies indicate that blood flow in the
fetal liver controls the fetal growth, and that
this flow depends on external factors as
maternal nutrition (especially late in
pregnancy)

19. • During acute challenges (Hypoxia and
hypovolemia) short term response involves
increasing the shunted blood across the DV to
ensure survival.
• If such challenges are maintained for a long
duration other adaptational mechanisms take
place as decreasing metabolic requirements
and circulatory redistributions.

20. Ultrasound imaging and insonation
• A Sagittal anterior insonation offers the best
visualization of the Ductus venosus .
• An oblique transverse section may be more
convenient and easier to obtain in some fetal
position but rarely offers visualization of the
entire length of the vessel.

22. • Color Doppler is an indispensable tool to
identify the high velocity flow at the isthmus
of the ductus venosus.
• Pulsed wave Doppler can be obtained in both
Sagittal and transverse view and no angle of
correction is usually needed.
• The sample volume should be kept as wide as
the geometric detail of the vessel to reduce
interference by surrounding vessels

26. Normal Ductus venosus Blood Velocity
• The ductus has a usually high flow during the
entire cardiac cycle compared to the
neighboring veins.
• Starting the early gestation the velocity
increases to reach a plateau at 22 weeks.
• For the rest of the pregnancy the PSV ranges
between 40-85 cm/s

27. • The velocity pattern reflects the with a peak
during systole and another during diastole ,
and a nadir during active diastolic filling(atrial
contraction).
• Typically this nadir doesn’t reach zero or
below zero during the second half of
pregnancy.
• However below 15 weeks a nadir zero or
below zero is being recorded in normal
fetuses.

28. Interpretation of the wave form
• The a-wave : Is the single most important part of
the waveform from a diagnostic point of view .
• The augmented artial contraction signifies an
increased end diastolic filling pressure of the
heart.
• Such pressure can be increased by increased
distention of the artia leading to an augmented
contraction (The Frank-Starling law) commonly
seen in cases of congestive heart failure and
increased preload

29. • An increased afterload can also produce such
an effect
• In cases of hypoxia this effect is believed to be
primarily a direct effect of hypoxia on the
myocardium.
• The heart rate is an important determinant for
the venous waveforms.
• A slower heat rate permits more time for
filling and thus results in a more augmented
atrial contraction. The effect is seen in fetal
bradycardia.

30. • An increased venous return causes a more
pronounced myocardial distention. Producing
the same effect this similar to the condition in
twin to twin transfusion and some AV
malformations.
• Hyperkinetic circulation such as in fetal
anemia increases the preload and with
deterioration in cardiac function congestive
heart faliure occurs and the effect is seen.

31. • The compliance of the heart is reflected by the
a-wave .
• A decrease in this compliance as in
myocarditis (parvo virus B19 infection)
,cardiomyopathies, hypoxemia and acidosis is
associated with a deepened a-wave.
• Increased pressure in the fetal chest as in
large tumors and effsuion or tracheal atresia,
causes further restriction in the cardiac
compliance .

32. • A significant tricuspid or mitral regruitation
attribute to an increased volume and pressure
in the atria causing augmented a-wave .

37. Pitfalls
• For the beginners Sampling in a neighbouring
vein or including interference from the IVC or
and other vessels may give a false impression
of an abnormal wave.

38. Ductus venosus vs. hepatic vein
• The velocity in the hepatic veins tend to be
more acute . Particularly that normal during
the second trimester these veins have a zero
or below a-wave.
• Before leaping to a conclusion it is prudent to
reproduce the wave in a renewed insonation.
• It is helpful to know that the abnormality in
the ductus venosus wave commonly has a
corresponding form in the U.V (umbilical vein)

41. • Local changes with no pathologic significance
can cause a change in the wave form . In
cases if the fetus is bending forward especially
with presence of oligohydramnios.
• Can cause squeezing of the IVC , the outlet or
the entire length of the ductus venosus to the
extent that most of the wave is reflected and
this can change with change in the fetal
position.

42. Agenesis of the Ductus Venosus
• An increasing number of case reports link
agenesis to fetal demise , hydrops fetalis ,
cardiac disorders and chromosomal
abnormality .

44. • In normal fetuses the a-wave is positive from
the first trimester onwards and the pulsatility
index for veins decreases with advancing
gestation
• High pulsatility index for veins and absent or
reversed a-wave are observed in fetuses with
aneuploidies, cardiac defects, growth
restriction and either the recipient or donor
fetus in twin-to-twin transfusion syndrome

45. a-wave reversal in the 1st trimester
• Reversed a-wave is associated with increased
risk for:
• Chromosomal abnormalities
• Сardiac defects
• Fetal death
• However, in about 80% of cases with reversed
a-wave the pregnancy outcome is normal

46. Reversal later in pregancy
• Unlike umbilical artery or MCA abnormalities
which may be present for weeks, absence or
reversal of ductus venosus a-wave appears to
occur late in progression of placenta based
IUGR.

47. Specific notes regarding Ductus
venosus and FGR .
• Changes preceeding stillbirth: Serial assessments
in pregnancies resulting in stillbirth have
demonstrated major differences in the responses
during the last three days preceeding death
depending on gestation:
• In stillbirths before 34 weeks there is a major
increase in the umbilical artery and ductus
venosus PI and decrease in amniotic fluid volume
and fetal tone and movements. The intensity of
monitoring should increase if there is worsening
in umbilical artery and/or ductus venosus PI or
decrease in amniotic fluid volume and may vary
from once per week to daily

48. Use of Ductus venosus and timing of
delivery
• Less than 28 weeks: reversed a-wave in the
ductus venosus and reversed end-diastolic
flow in the umbilical artery and deepest
pocket of amniotic fluid less than 2 cm and no
movements

49. • 28-30 weeks: reversed a-wave in the ductus
venosus orreversed end-diastolic flow in
the umbilical artery and deepest pocket of
amniotic fluid less than 2 cm and no
movements

50. • 31-33 weeks: absent end-diastolic flow in the
umbilical artery or absent a-wave in the
ductus venosus or deepest pocket of amniotic
fluid less than 2 cm and no movements

51. ACOG bulletin 134 (2013)
• Daily surveillance with NST/BPP; serial UA
Dopplers
• Corticosteroids to accelerate fetal lung maturity
• Individualize fetal assessment
• Deliver at point that fetal risk in-utero appears
greater than risk of prematurity
• Additional Doppler surveillance
• MCA diastolic flow evaluation
• Ductus venosus
• Magnesium sulfate for neuroprotection if delivery
< 32 weeks

52. RCOG Greentop guideline
no.31
2nd Edition | February
2013 | Minor revisions –
January 2014

53. • Ductus venosus Doppler has moderate
predictive value for acidaemia and adverse
outcome (A)
• Ductus venosus Doppler should be used for
surveillance in the preterm SGA fetus with
abnormal umbilical artery Doppler and used
to time delivery. (A)

54. • In the preterm SGA fetus with umbilical artery
AREDV detected prior to 32 weeks of
gestation, delivery is recommended when DV
Doppler becomes abnormal or UV pulsations
appear, provided the fetus is considered viable
and after completion of steroids.(good
practice point)

55. • Even when venous Doppler is normal, delivery
is recommended by 32 weeks of gestation and
should be considered between 30–32 weeks
of gestation (good practice point)

56. • The Ductus venosus (DV) Doppler flow
velocity pattern reflects atrial pressure–
volume changes during the cardiac cycle.
• As FGR worsens velocity reduces in the DV a–
wave owing to increased afterload and
preload, as well as increased end–diastolic
pressure, resulting from the directs effects of
hypoxia/acidaemia and increased adrenergic
drive.

57. • A retrograde a–wave and pulsatile flow in the
umbilical vein (UV) signifies the onset of overt
fetal cardiac compromise.
• No systematic reviews of effectiveness of
venous Doppler as a surveillance tool in high
risk or SGA fetuses were identified (Evidence
level 1+)

58. • Observational studies have identified venous
Doppler as the best predictor of acidaemia
(Evidence level 2–)

59. Umbilical vein
• The umbilical vein should be examined either
within the fetal abdomen or in the umbilical
cord
• The flow is constant from 12 weeks onwards
in 90% of the fetuses
• Monophasic pulsations are relevant if central
veins are abnormal
• Clinical application of umbilical venous
Doppler: fetal growth restriction, twin-to-twin
transfusion syndrome and hydrops fetalis

60. • Pulsations are observed in 10% of fetuses and
these can be:
• Monophasic
• Biphasic
• Triphasic
• Multiphasic pulsations indicate abnormally
high venous pressure