Color Doppler ultrasound in the high risk pregnancy

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Color Doppler ultrasound in the high risk
pregnancy

• Presented by
• Dr. Farzad Afzali
• Kasra medical imaging center

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• An early stage in fetal adaptation to
  hypoxemia
• increased blood flow in DV to protect the brain,
  heart, and adrenals
• central redistribution of blood flow (
  brain-sparing reflex)
• reduced flow to the peripheral and placental
  circulations

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Under physiologic conditions, 60 to 70 percent of
umbilical venous blood in the human fetus is
distributed to the liver and the remainder to the
heart. With chronic hypoxemia, this proportion
may be modulated so that a larger proportion of
umbilical venous blood can bypass the liver to
reach the heart
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Long term outcomes need to be examined

• Middle cerebral artery
• Aorta
• Umbilical artery
• Uterine artery
• IVC
• Ductus venosus

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• The middle cerebral artery (MCA) in the fetal
  brain
• Normally high-impedance
• Most accessible to U/S imaging
• More than 80 of cerebral blood
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MCA
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Comment

• Average of both MCAs must be calculated for more
  precise result.
• Compression of the fetal head causes increasing
  arterial resistance.( false negative of IUGR)

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• The best predictor for fetal acidemia is PI of
  thoracic aorta.
• The best predictor of fetal hypoxia is PI of MCA.

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Fetal Aorta
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• The damage that obliterate small muscular
  arteries in placental tertiary stem villi
• absent flow or even reversed flow, suggestive
  more than 70 damage of placenta.
• commonly associated with severe IUGR and
  oligohydramnios
• Waveforms obtained from the placental end of cord
  show more end-diastolic flow, thus lower RI PI,
  than waveforms obtained from the abdominal cord
  insertion. (No significance on clinical practice)

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Umbilical artery
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Uterine artery
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• Velocimetry of uterine artey should be obtained
  after the vessel crosses the hypo gastric artery
  and vein, at the uterus-cervical junction, before
  it divides to cervical and uterine branches.
• The best predictor of PIH is notch in the uterine
  artery RIgt61.5 after 22 w of gestation.

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Uterine artery
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Pathological changes in venous flows with FGR

• Venous indices reflect
• ventricular function
• Fetal hypoxia
• Myocardial lactic acidosis

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• Decrease cardiac output secondary to myocardial
  dysfunction
• Rise in CVP
• Increase in reverse flow in atrial systole
• Transmitted down venous system - the further from
  the heart the greater degree of cardiac
  dysfunction

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Pattern continued

• DV a wave decrease
• Reverse EDF UA -- Reverse a wave DV
• Pulsatile UV
• Constriction of cerebral circulation
• Death within 96 hours

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• At the level of AC measuring, ductus venosus can
  be identified as it branches from hepatic vein.
• It has high speed flow with biphasic waveform.
• The first phase corresponding ventricular
  systole, the second phase to early diastole and
  nadir to the atrial kick.

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Umbilical vein

• Umbilical vein displays pulsatility in first
  trimester but this disappears with advancing
  gestation in the pregnancy unaffected by FGR

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• In clinical practice, it is necessary to carry
  out serial Doppler investigations to estimate the
  duration of fetal blood flow redistribution.
• The onset of abnormal venous Doppler results
  indicates deterioration in the fetal condition
  and iatrogenic delivery should be considered

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• PI of MCA/PI of TA must be more than 0.9 before
  30,less than 0.8 before the 34 less than 0.75
  before the 36 weeks of pregnancy.
• PI of MCA/ PI of UA must be gt1.08 during
  pregnancy.
• The larger values are abnormal termination may
  be considered after 35-37 weeks of pregnancy.

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Preterm growth restricted fetuses with elevated
umbilical artery Doppler resistance have an
overall perinatal mortality rate of 5.6 percent .
This rate increases to 11.5 percent when
end-diastolic velocity is absent. and rises to
38.8 percent when venous Doppler indices become
abnormal (predominantly due to an increase in the
rate of stillbirth).
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• Reverse flow in the umbilical artery, along with
  pathologic waveform in the venous system are the
  best predictor of sever fetal distress, so
  termination of pregnancy must be considered as
  soon as possible.

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