Doppler Ultrasound in Pregnancy

Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com) Doppler Ultrasound in Pregnancy Tutorial [1] | Aug...
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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Doppler Ultrasound in Pregnancy Tutorial [1] | August 17, 2011 By Mohammed Abdalla, MD [2] Doppler History • Fitzgerald & Drumm. Umbilical artery studies 1977 BMJ • Eik-Nes et al. Fetal aortic velocimetry: Dupplexscanner 1980 Lancet • Campbell et al. Utero-placental circulation: Dupplex scanner 1983 Lancet • Wladimiroff et al. MCA/UA PI ratio 1987 OG Kiserud et al. Ductus venosus velocimetry 1991 Lancet

DOPPLER ULTRASOUND in Pregnancy Dr. Mohammed Abdalla Egypt, Doimat Hospital

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Doppler History First use of Doppler ultrasonography to study flow velocity in the fetal umbilical artery was reported in 1977

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Doppler History • Fitzgerald & Drumm. Umbilical artery studies 1977 BMJ • Eik-Nes et al. Fetal aortic velocimetry: Dupplexscanner 1980 Lancet • Campbell et al. Utero-placental circulation: Dupplex scanner 1983 Lancet • Wladimiroff et al. MCA/UA PI ratio 1987 OG Kiserud et al. Ductus venosus velocimetry 1991 Lancet

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Basic principals Echoes from stationary tissues are the same from pulse to pulse. Echoes from moving objects exhibit slight differences in the time for the signal to be returned to the receiver. These differences can measured as phase shift from which the Doppler frequency is obtained.

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

T1: time of omitted signal. T2: time of returned signal. T2 - T1 = time difference or phase shift. from phase shift the Doppler frequency is obtained. AS TIME DIFFERENCE DECREASE THE DOPPLER FREQUENCY INCREASE.

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Basic principals The time difference or phase shift are then proceeded to produce either colorflow display or a Doppler sonogram

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Basic principals • 'Doppler frequency' is obtained by measuring the time difference for the signal to be returned when reflected from moving scatterers. • Doppler frequency increase if: 1. flow velocity increased. 2. beam is more aligned to the direction of flow. 3. higher transducer frequency is used.

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Factors affecting doppler frequency (the angle q between the beam and the direction of the flow becomes smaller). This is of the utmost importance in the use of Doppler ultrasound.

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

(the angle q between the beam and the direction of the flow becomes smaller). This is of the utmost importance in the use of Doppler ultrasound. beam (A) is more aligned than (B) The beam/flow angle at (C) is almost 90° and the The flow at (D) is away from the beam and there

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

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

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Aliasing So to eliminate aliasing The pulse repetition frequency or scale is set appropriately for the flow velocities.

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

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

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Uses • plays a vital role in the diagnosis of fetal cardiac defects. • assessment of the hemodynamic responses to fetal hypoxia and anemia. • diagnosis of other non-cardiac malformations.

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Anatomy • Blood supply provided by the ovarian and uterine arteries • Uterine Ateries: main branches of the internal iliac arteries • Uterine Ateries: Ascend through the lateral wall and anastomose with the ovarian arteries

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Anatomy • Acurate Arteries: Run Circumferentially around the uterus • Uterus: Blood supply to anterior and posterior walls provided by the Arcuate arteries • Radial Arteries: Extend from the arcuate arteries and enter the endometrium • Spiral Arteries: connect the maternal circulation to the endometrium • Responsible for a 10 fold increase in blood flow

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

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

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Umbilical artery doppler

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Umbilical artery UMBILICAL ARTERY FLOW characteristic saw-tooth appearance of arterial flow in one direction and continuous umbilical venous blood flow in the other.

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

FACTORS AFFECTING UMBILICAL ARTERY DOPPLER FLOW VELOCITY WAVEFORMS* Gestational age Fetal heart rate Fetal breathing movements

EDFV ratio increases with advancing gestational age15 EDFV decreases with decreasing feal heart rate13,41 Increases variability in the measurements66

Site of measurement

EDFV is higher near the ubmilical cord insertion into the fetal abdomen than near the placental insertion67 Equipment used: continous Doppler verus pulsed Continuous Doppler is more a "blind Doppler technique" compared with pulsed Duplex Doppler, allowing 2D real time ultrasound User experience Reliability increases with increasing experience69 Radius of the umbilical artery Decreasing radius (vasoconstriction) increase EDFV70 Impedance to pulsatile low propagation Increaing vascular impedance increases EDFV70 Downstream vascular resistance within the Increaing vascular impedance decreases microcirculaton EDFV70-72 Angle of the fetal Doppler insonation Best if less than 45, 72 absolute peak systolic flow velocity62,64 EDVF= end diastolic flow velocity; MCA = middle cerebral artery.

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Umbilical artery Benefit of Umbilicial Artery Evaluation Less experienced operators can achieve highly reproducible results with simple, inexpensive continuous-wave equipment.

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

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

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

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

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Middle cerebral artery doppler

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

The possible Doppler velocimetry sites Middle cerebral artery 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

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

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

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

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

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Doppler wave form of early stage of fetal hypoxemia increase end-diastolic flow in the middle cerebral artery (lower MCA pulsatility index or resistance index) Average of both MCAs must be calculated for more precise result

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

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

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

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

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Doppler ultrasound for the fetal assessment in high-rish pregnancies (Cochrane Review). In: The Cochrane Library,, 1999. Neilson JP and Alfirevic Z 11 Studies Included In Analysis • Trudinger et all 1987 • McParland et all 1988 •Tyrrell et al 1990 •Hofmeyer et all 1991 •Newham et all 1991 •Burke et al 1992 •Almstrom et al 1992 •Biljan et al 1992 •Johnstone et all 1993 •Pattison et al 1994 •Nienhuis et al 1997

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Doppler ultrsound for the fetal assessment in the high-risk pegnancies Meta analysis • Nearly 7000 patients were included • The trials compared no Doppler ultrasound to Doppler ultrasound in high-risk pregnancy (hypertension or presumed impaired fetal growth)

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Doppler ultrasound for the fetal assessment in high-risk pregnancies Main results • A reduction in perinatal deaths. • Fewer inductions of labour. • Fewer admissions to hospital. • no report of adverse effects. • No difference was found for fetal distress in labour. • No difference in casesaren delivery.

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Biophysical profile for fetal assessments in high risk pregnancies • When compared with conventional fetal monitoring (usually cardiotocography) biophysical profile testing showed no obvious effect (either beneficial or deleterious) on pregnancy outcome. There was an increase in the number of inductions of labour following biophysical profile in the trial. Alfirevic A, Neilson JP. Biophysical profile for fetal assessment in the high risk pregnancies (Cochrane Review). In: The Cochrane Library, 1995.

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Doppler Ultrasound in Pregnancy Published on Diagnostic Imaging (http://www.diagnosticimaging.com)

Thank you

Source URL: http://www.diagnosticimaging.com/tutorial/doppler-ultrasound-pregnancy Links: [1] http://www.diagnosticimaging.com/tutorial [2] http://www.diagnosticimaging.com/authors/mohammed-abdalla-md

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