DOPPLER ULTRASOUND DOPPLER ULTRASOUND in Pregnancyin Pregnancy

Dr. Mohammed AbdallaDr. Mohammed AbdallaEgypt, Domiat HospitalEgypt, Domiat Hospital

First use of Doppler First use of Doppler ultrasonography to study ultrasonography to study

flow velocity in the fetal flow velocity in the fetal umbilical arteryumbilical artery

was reported in was reported in 19771977

Doppler HistoryDoppler History

Doppler HistoryDoppler History

Fitzgerald & Drumm. Fitzgerald & Drumm. Umbilical artery studiesUmbilical artery studies 1977 1977BMJBMJ

Eik-Nes et al. Eik-Nes et al. Fetal aortic velocimetryFetal aortic velocimetry : Dupplexscanner : Dupplexscanner 1980 1980 LancetLancet

Campbell et al. Campbell et al. Utero-placental circulationUtero-placental circulation: Dupplex : Dupplex scanner 1983 scanner 1983 LancetLancet

Wladimiroff et al. Wladimiroff et al. MCA / UA PI ratioMCA / UA PI ratio 1987 1987 OGOG

Kiserud et al. Kiserud et al. Ductus venosus velocimetryDuctus venosus velocimetry 1991 1991LancetLancet

Basic principalsBasic principals

Echoes from stationary tissues are the same from Echoes from stationary tissues are the same from pulse to pulse. pulse to pulse.

Echoes from moving objects exhibit slight Echoes from moving objects exhibit slight differences in the time for the signal to be differences in the time for the signal to be returned to the receiver.returned to the receiver.

These differences can measured as These differences can measured as phase shiftphase shift from which the from which the Doppler frequencyDoppler frequency is is obtained. obtained.

..

T1T1 : time of omitted signal : time of omitted signal . .

T2T2 : time of returned signal . : time of returned signal .

T2 – T1 = T2 – T1 = time difference or phase time difference or phase shift .shift .

from phase shift the Doppler frequency from phase shift the Doppler frequency is obtained.is obtained.

AS TIME DIFFERENCE DECREASE THE AS TIME DIFFERENCE DECREASE THE DOPPLER FREQUENCY INCREASE.DOPPLER FREQUENCY INCREASE.

pulse repetition frequencypulse repetition frequency

(T2 –T1) phase shiftphase shift with known beam / flow angle can calculate flow velocity .

T1

T2

The time difference or phase shift The time difference or phase shift are then proceeded to produce are then proceeded to produce either either colorflow displaycolorflow display or a or a

Doppler sonogramDoppler sonogram

Basic PrincipalsBasic Principals

Basic PrincipalsBasic Principals

‘‘Doppler frequency’ is obtained by measuring Doppler frequency’ is obtained by measuring the time difference for the signal to be returned the time difference for the signal to be returned when reflected from moving scatterers .when reflected from moving scatterers .

Doppler frequency increase if:Doppler frequency increase if:1.1. flow velocity increased .flow velocity increased .

2.2. beam is more aligned to the direction of beam is more aligned to the direction of

flow.flow.

3.3. higher transducer frequency is used.higher transducer frequency is used.

(the angle (the angle qq between the beam and the direction of between the beam and the direction of flow becomes smaller). This is of the utmost flow becomes smaller). This is of the utmost importance in the use of Doppler ultrasound. importance in the use of Doppler ultrasound.

Freq.

qq

The angle of insonation

Flow velocity

3

2

1

Factors affecting doppler frequency

(the angle (the angle qq between the beam and the direction of flow between the beam and the direction of flow becomes smaller). This is of the utmost importance in the becomes smaller). This is of the utmost importance in the use of Doppler ultrasound. use of Doppler ultrasound.

beambeam (A) (A) is more aligned than is more aligned than (B)(B)

The beam/flow angle at The beam/flow angle at (C) (C) is almost 90° and there is a very poor Doppler signalis almost 90° and there is a very poor Doppler signal

The flow at The flow at (D) (D) is away from the beam and there is a negative signal.is away from the beam and there is a negative signal.

AliasingAliasing

If a second pulse is sent before the first is received, the receiver cannot discriminate between the reflected signal from both pulses and aliasing occur.

So to eliminate aliasing The So to eliminate aliasing The pulse repetition frequency or pulse repetition frequency or scale is set appropriately for scale is set appropriately for

the flow velocities the flow velocities

AliasingAliasing

The volume flow in the UAs increases The volume flow in the UAs increases with advancing gestation. The high with advancing gestation. The high vascular impedance detected in the vascular impedance detected in the first trimester gradually decreases. first trimester gradually decreases. It is attributed to growth of placental It is attributed to growth of placental unit and increase in the number of unit and increase in the number of the functioning vascular channels.the functioning vascular channels.

Basic PrincipalsBasic Principals

UsesUsesplays a vital role in the diagnosis of plays a vital role in the diagnosis of fetal fetal cardiac defectscardiac defects . .

assessment of the hemodynamic assessment of the hemodynamic responses to fetal responses to fetal hypoxiahypoxia and and anemiaanemia. .

diagnosis of other diagnosis of other non-cardiac non-cardiac malformations. malformations.

Blood supply provided by Blood supply provided by the ovarian and uterine the ovarian and uterine arteriesarteries

Uterine Arteries: main Uterine Arteries: main branches of the internal branches of the internal iliac arteriesiliac arteries

Uterine Arteries: Ascend Uterine Arteries: Ascend through the lateral wall and through the lateral wall and anastomose with the anastomose with the ovarian arteriesovarian arteries

Blood supply provided by Blood supply provided by the ovarian and uterine the ovarian and uterine arteriesarteries

Uterine Arteries: main Uterine Arteries: main branches of the internal branches of the internal iliac arteriesiliac arteries

Uterine Arteries: Ascend Uterine Arteries: Ascend through the lateral wall and through the lateral wall and anastomose with the anastomose with the ovarian arteriesovarian arteries

AnatomyAnatomyAnatomyAnatomy

Spiral Arteries: connect the maternal circulation to the Spiral Arteries: connect the maternal circulation to the endometriumendometrium

Responsible for a 10 fold increase in blood flowResponsible for a 10 fold increase in blood flow

Spiral Arteries: connect the maternal circulation to the Spiral Arteries: connect the maternal circulation to the endometriumendometrium

Responsible for a 10 fold increase in blood flowResponsible for a 10 fold increase in blood flow

AnatomyAnatomyAnatomyAnatomy Arcuate Arteries: Run Circumferentially around the uterus Arcuate Arteries: Run Circumferentially around the uterus Uterus: Blood supply to anterior and posterior walls Uterus: Blood supply to anterior and posterior walls

provided by the Arcuate arteriesprovided by the Arcuate arteries Radial Arteries: Extend from the arcuate arteries and Radial Arteries: Extend from the arcuate arteries and

enter the endometriumenter the endometrium

Arcuate Arteries: Run Circumferentially around the uterus Arcuate Arteries: Run Circumferentially around the uterus Uterus: Blood supply to anterior and posterior walls Uterus: Blood supply to anterior and posterior walls

provided by the Arcuate arteriesprovided by the Arcuate arteries Radial Arteries: Extend from the arcuate arteries and Radial Arteries: Extend from the arcuate arteries and

enter the endometriumenter the endometrium

Conversion of small muscular spiral arteries into large Conversion of small muscular spiral arteries into large vascular channels transforms the uteroplacental vascular channels transforms the uteroplacental circulation into a low-resistance-to-flow system. These circulation into a low-resistance-to-flow system. These have a dilated and tortuous lumen, a complete absence have a dilated and tortuous lumen, a complete absence of muscular and elastic tissue, no continuous of muscular and elastic tissue, no continuous endothelial lining.endothelial lining.

Conversion of small muscular spiral arteries into large Conversion of small muscular spiral arteries into large vascular channels transforms the uteroplacental vascular channels transforms the uteroplacental circulation into a low-resistance-to-flow system. These circulation into a low-resistance-to-flow system. These have a dilated and tortuous lumen, a complete absence have a dilated and tortuous lumen, a complete absence of muscular and elastic tissue, no continuous of muscular and elastic tissue, no continuous endothelial lining.endothelial lining.

AnatomyAnatomyAnatomyAnatomy

Umbilical artery doppler

Doppler indices

UMBILICAL ARTERY FLOW

characteristic saw-tooth appearance of arterial flow in one direction and continuous umbilical venous blood flow in the other.

Umbilical arteryUmbilical artery

FACTORS AFFECTING UMBILICAL ARTERY DOPPLER FACTORS AFFECTING UMBILICAL ARTERY DOPPLER FLOW VELOCITY WAVEFORMSFLOW VELOCITY WAVEFORMS**

Benefit of Umbilical Artery EvaluationBenefit of Umbilical Artery Evaluation

Less experienced operators can achieve Less experienced operators can achieve highly reproducible results with simple, highly reproducible results with simple, inexpensive continuous-wave inexpensive continuous-wave equipment .equipment .

Umbilical arteryUmbilical artery

The 40% of the combined fetal ventricular output is directed to the placenta by two umbilical arteries. The assessment of umbilical blood flow The 40% of the combined fetal ventricular output is directed to the placenta by two umbilical arteries. The assessment of umbilical blood flow provides information on blood perfusion of the fetoplacental unit .provides information on blood perfusion of the fetoplacental unit .

..

Umbilical arteryUmbilical artery

With advancing gestation, With advancing gestation, umbilical arterial Doppler umbilical arterial Doppler waveforms demonstrate a waveforms demonstrate a progressive rise in the progressive rise in the end-diastolic velocity and end-diastolic velocity and a decrease in the a decrease in the pulsatility index. pulsatility index.

Umbilical arteryUmbilical artery

Middle cerebral artery doppler

Using color flow imaging, the middle cerebral artery can be seen as a major lateral branch of the circle of Willis, running anterolaterally at the borderline between the anterior and the middle cerebral fossae

The possible Doppler velocimetry sitesThe possible Doppler velocimetry sites

Middle cerebral artery

Middle cerebral arteryMiddle cerebral artery

The blood velocity increases with advancing gestation, and this increase is significantly associated with the decrease in PI

An early stage in fetal adaptation   to  hypoxemia - An early stage in fetal adaptation   to  hypoxemia - central redistribution of blood flowcentral redistribution of blood flow

      ( brain-sparing reflex)  ( brain-sparing reflex)  increased blood flow to protect the brain, heart, increased blood flow to protect the brain, heart,

and adrenals and adrenals reduced flow to the peripheral and placental reduced flow to the peripheral and placental

circulationscirculations              

Middle cerebral arteryMiddle cerebral artery

Doppler wave form of early stage ofDoppler wave form of early stage of        fetal hypoxemiafetal hypoxemia  

increased end-diastolic flow in the middle increased end-diastolic flow in the middle cerebral artery (lower MCA cerebral artery (lower MCA pulsatility pulsatility indexindex or resistance or resistance indexindex))

  Average of both MCAs must be calculated Average of both MCAs must be calculated for more precise result for more precise result

Middle Cerebral ArteryMiddle Cerebral Artery

Flow velocity waveform in the fetal middle cerebral artery Flow velocity waveform in the fetal middle cerebral artery in a severely anemic fetus at 22 weeks (left) and in a in a severely anemic fetus at 22 weeks (left) and in a normal fetus (right). In fetal anemia, blood velocity is normal fetus (right). In fetal anemia, blood velocity is increasedincreased

When the fetus is hypoxic, the cerebra arteries When the fetus is hypoxic, the cerebra arteries tend to become dilated in order to preserve tend to become dilated in order to preserve the blood flow to the brain and The systolic to the blood flow to the brain and The systolic to diastolic (A/B) ratio will decrease (due to an diastolic (A/B) ratio will decrease (due to an increase in diastolic flow)increase in diastolic flow)

Middle Cerebral ArteryMiddle Cerebral Artery

Doppler ultrasound for the fetal assessment in Doppler ultrasound for the fetal assessment in high-risk pregnancies high-risk pregnancies

(Cochrane Review). In: (Cochrane Review). In: The Cochrane Library, The Cochrane Library, 1999. Neilson JP and Alfirevic Z1999. Neilson JP and Alfirevic Z

Trudinger et al 1987Trudinger et al 1987 McParland et al 1988McParland et al 1988 Tyrrell et al 1990Tyrrell et al 1990 Hofmeyr et al 1991Hofmeyr et al 1991 Newham et al 1991Newham et al 1991 Burke et al 1992Burke et al 1992

11 Studies Included In Analysis

Almstrom et al 1992Biljan et al 1992Johnstone et al 1993Pattison et al 1994Nienhuis et al 1997

Doppler ultrasound for the fetal assessment Doppler ultrasound for the fetal assessment in high-risk pregnanciesin high-risk pregnancies

Nearly 7000 patients were includedNearly 7000 patients were included

The trials compared no Doppler ultrasound to The trials compared no Doppler ultrasound to Doppler ultrasound in high-risk pregnancy Doppler ultrasound in high-risk pregnancy (hypertension or presumed impaired fetal (hypertension or presumed impaired fetal growth)growth)

Meta analysis

Doppler ultrasound for the fetal assessment Doppler ultrasound for the fetal assessment in high-risk pregnanciesin high-risk pregnancies

A reduction in perinatal deaths.A reduction in perinatal deaths.Fewer inductions of labour .Fewer inductions of labour .Fewer admissions to hospital .Fewer admissions to hospital .no report of adverse effects .no report of adverse effects .No difference was found for fetal distress No difference was found for fetal distress

in labour .in labour .No difference in caesarean delivery .No difference in caesarean delivery .

Main results

Biophysical profile for fetal assessment inBiophysical profile for fetal assessment inhigh risk pregnancieshigh risk pregnancies

• • When compared with conventional fetal monitoring When compared with conventional fetal monitoring (usually cardiotocography) biophysical profile (usually cardiotocography) biophysical profile testing showed no obvious effect (either beneficial testing showed no obvious effect (either beneficial or deleterious) on pregnancy outcome. There was or deleterious) on pregnancy outcome. There was an increase in the number of inductions of labour an increase in the number of inductions of labour following biophysical profile in the trial.following biophysical profile in the trial.

Alfirevic Z, Neilson JP. Biophysical profile for fetal assessment in high risk pregnancies (CochraneReview). In: The Cochrane Library, 1995.