prof. dr. mohamed mahmoud waly prof. dr. abdalla yahya el ... · iufd intrauterine fetal death sga...
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THE VALUE OF MIDDLE CEREBRAL TO UMBILICAL ARTERY PULSATILITY INDEX RATIO IN THE PREDICTION OF ADVERSE NEONATAL OUTCOME IN PREECLAMPSIA
A protocol of thesis submitted for partial fulfillment of Master Degree in Obstetrics and Gynecology
Presented by
Shimaa Abdou Soubh (M.B.B.Ch.)2004,Cairo university
Resident Obstetrics& Gynecology doctor at Damietta specialized hospital
Supervised by
Prof. Dr. Mohamed Mahmoud Waly
Prof. of Obstetrics & Gynecology Faculty of Medicine
Cairo University
Prof. Dr. Abdalla Yahya El Kateb Assist. Prof. of Obstetrics & Gynecology
Faculty of Medicine Cairo University
Faculty of Medicine Cairo University
2012
Acknowledgement
First of all I thank God for all his giving throughout my life, I thank my family for their continuous support through all the hard and difficult times.
I would like to express my deepest gratitude and thanks to Prof. Dr. Mohammed Mahmoud Waley Professor of Obstetrics & Gynecology Faculty of Medicine- Cairo University, who gave me the honor of working under her supervision and follow up of the progress of this work..
I wish to express my deepest thanks and gratitude to Dr. Abdalla yahya Elkateb, assistant professor of Obstetrics & Gynecology, Faculty of Medicine- Cairo University, for guiding me all through this thesis and revising all my work so I give her all my sincere thanks for her effort and time .
Dedication
To my Father and my Mother who taught me the principles and patience
To my husband who support me
To son abd elrahman
To all my professors and colleagues
Contents
Page
Introduction and Aim of the work 1 Review of literature
• Doppler velocimetry
• Preeclampsia
• Methodology of Doppler assessment of placenta & fetal circulation
• Doppler study in fetal hypoxic hypoxia
6
36
85
112
Patients and methods Results Discussion Summary Conclusion References Arabic summary
165 171 189 196 198 199
ABSTRACT OBJECTIVE. Our aim was to assess the accuracy of the Middle cerebral to Umbilical Artery (PI) ratio in predicting fetal out come in pregnancies complicated by preeclampsia. METHODS. We evaluate 75 pregnant women representing clinical forms of preeclampsia. Seventy-five cases with no signs of preeclampsia were accepted as controls. Pulse wave color Doppler with 3.5MHz probe was used in the assessments of fetal and maternal circulation. Cerebral to umbilical ratio was obtained by the division of MCA PI to UA PI. Apgar score will be assessed at 5 minutes after birth. Apgar score < 7 at 5 minutes and or neonatal admission to neonatal intensive care unit (NICU) will indicate neonatal morbidity.
Perinatal outcome was evaluated in relation to the indices. RESULTS. Umbilical artery showed elevated indices in preeclamptic patient than control group, Absent end diastolic velocity (AEDV) and reversed end diastolic velocity (REDV) were seen in 9 cases respectively and were associated with poor perinatal outcome. MCA values were decreased in preeclamptic patient and had poor perinatal outcome in terms of need for lower segment cesarean section (LSCS) for fetal distress, apgar <7 at 5minute, and admission to nursery. Cerebroumbilical (C/U) ratio of <1.1 was similarly associated with poor perinatal outcome. Conclusions: In normal pregnancy there is gestational age related fall in impedance in umbilical and middle cerebral arteries. cerebral–umbilical ratio is strong predictors of IUGR and of adverse perinatal outcome in preeclampsia. The MCA PI alone is not a reliable indicator. The combination of umbilical and fetal cerebral Doppler indices may increase the utility of Doppler ultrasound in preeclamptic subjects. Key Words: Doppler velocimetry, Preeclampsia, Methodology of Doppler assessment of placenta & fetal circulation, Doppler study in fetal hypoxic hypoxia.
List of Tables
Page Title Table no
76 Laboratory finding in preeclampsia 1 77
Criteria for the diagnosis of severe preeclampsia
2
100 umbilical artery Doppler indices in normal pregnancy
3
104 Factors affecting umbilical artery Doppler flow velocity waveforms
4
109 middle cerebral artery Doppler indices in normal pregnancy
5
125
Umbilical artery indices in preeclampsia and normal pregnancy
6
127 the mean values of Umbilical Artery Doppler Velocimetric indices in hypertensive and normotensive groups
7
131 Fetal systemic vascular responses during hypoxemia induced by uteroplacental insufficiency
8
132
Hemodynamic changes occurring in fetal arterial vessels during hypoxemia and acidemia induced uteroplacental insufficiency. by
9
140 cerebroplacental ratio (C/U) ratio in normal pregnancies
10
142 Doppler indices of normal pregnancies and preeclamptic patients with or without IUGR
11
156 Follow up studies of children exposed to absent or reverse end diastolic flow in utero.
12
176 Comparison between both studied groups as regard general data
13
176 Comparison between both studied groups as regard parity
14
177 Comparison between both studied groups as regard hemodynamic parameters
15
180 Comparison between both studied groups as regard Apgar 5 score and fetal weight
16
180 Comparison between both studied groups as regard blood pressure
17
181 Distribution of the studied cases as regard diagnosis
18
181 Distribution of the studied cases as regard NICU 19 182 Correlation between CPR versus general data
among the cases 20
182 Correlation between CPR versus general data among controls
21
184 Correlation between CPR versus blood pressure among the cases
22
186 Correlation between CPR versus blood pressure among controls
23
186 Correlation between CPR versus Apgar and fetal weight among cases
24
187 Correlation between CPR versus Apgar and fetal weight among controls
25
187 Comparison between mild versus severe preeclampsia as regard CPR
26
189 Relation between NICU admission versus CPR 27 190 Validity of CPR in prognosis of preeclampsia 28 191 Validity of CPR in prognosis of fetal outcome
(NICU) 29
List of figures Page 1 (A) Continuous wave Doppler transducer ,
(B) pulsed wave Doppler transducer 13
2 Doppler indices 16 3 An illustration of the aliasing effect of an
arterial spectrum where the peak velocities have been too fast to measure with the particular pulse repetition frequency of a pulsed Doppler system
24
4 Flow velocity waveforms of the umbilical artery with advancing gestation.
29
5 Typical umbilical artery and vein waveform. 32 6 The normal values for the umbilical artery. 33 7 Normal placental implantation shows
proliferation of extravillous trophoblasts, forming a cell column beneath the anchoring villus.
44
8 Pathophysiological considerations in the development of hypertensive disorders due to pregnancy
46
9 Normal pregnancy development of the uterine artery
92
10 Diagrammatic representation of the effects of spiral artery conversion on the inflow of maternal blood into the intervillous space
92
11 Umbilical arterial flow 95 12 umbilical arterial flow: The volume flow in
the umbilical artery increases with advancing gestation.
98
13 Systole (Sys) and diastole (D) are identified in green Note that diastole is less at 20 weeks (yellow ellipse) than at 36 weeks (red
98
ellipse). 14 Normal pregnancy development of the
umbilical artery 99
15 Scattered diagram of umbilical artery pulsatility index from free loop of the cord against period of gestation with 5th,50th and 95th percentile line.
102
16 scattered diagram of umbilical artery systolic/diastolic ratio from the free loop of the cord against period of gestation with 5th,50th and 95th percentile line.
102
17 Transverse view of the fetal head with color Doppler showing the circle of Willis (left). Flow velocity waveforms from the middle cerebral artery at 32 weeks of gestation (right).
107
18 Normal Pregnancy - Development of the Middle Cerebral Artery
108
19 Pulsatility index (left) and mean blood velocity (right) in the fetal middle cerebral artery with gestation
110
20 individual measurements and calculated reference ranges for the pulsatility index (PI) in the MCA.
111
21 Absent blood flow during diastole in the umbilical artery
121
22 Reversed blood flow during diastole in the umbilical artery
121
23 Abnormal development of the umbilical artery.
122
24 Color Doppler examination of the circle of Willis (left). Flow velocity waveforms from the middle cerebral artery in a normal fetus with low diastolic velocities (right, top) and in a growth-restricted fetus with high diastolic velocities (right, bottom)
130
25 brain sparing phenomenon; (A) Middle cerebral artery waveform in a fetus 31 weeks with normal flow, pulsatility index for this fetus 2.02. ( B) a fetus at 32 weeks with brain sparing, as evidenced by an increased MCA diastolic flow velocity waveform that corresponds to a decreased pulsatility index, the pulsatility index for this fetus 0.90
136
26 CPR from 21 weeks to 42 weeks in normal pregnancies
141
List of Abbreviations
Abbreviation Meaning (CW)Doppler continuous wave Doppler (PW)Doppler pulsed wave Doppler (FD) Doppler shift (SPTA) Doppler spatial peak-temporal average-intensity (CPD) Color power Doppler PI Pulsatility index RI Resistance index FIP Frequency index profile S/D Ratio systolic/diastolic ratio (EVT) extravillous trophoblast HLA Human leucocytic antigen (NK) cells Natural killer cells (TNF) Tumor necrosis factor (NO) Nitric oxide VEGF Vascular endothelial growth factor (PIGF) Placental Growth Factor FDP Fibrin degradation products BP BLOOD PRESSURE PIH pregnancy induced hypertension IUGR intrauterine growth retardation MCA Middle cerebral artery UA Umbilical artery FVW flow velocity waveform ( AEDV) Absent end diastolic velocity (REDV) Reversed end diastolic velocity FBP Fetal biophysical profile C/U ratio cerebroumbilical ratio GA Gestational age DV Ductus venosus IUFD Intrauterine fetal death SGA Small for gestational age
Introduction and Aim of the Work
1
INTRODUCTION
Techniques of Doppler Ultrasonography (US) have been
available to clinicians for nearly 40 years. The Doppler effects as
developed by sound propagation in human tissues and with the
velocities observed for the human vasculature produces shifts in the
frequencies of returning echo signals. These signals can be
processed in a manner that allows the observer to determine the
condition of the blood flow (Boote, 2003).
Preeclampsia, a hypertensive disorder of pregnancy which
usually develops after 20 weeks of gestation characterized by
elevated blood pressure, proteinuria and /or edema. (Maynard et al.,
2008).
Preeclampsia remains a major cause of maternal and neonatal
morbidity and death (Norwitz et al.,2008).
In normal pregnancy impedance to flow in the uterine arteries
decrease with gestation and histopathological studies suggest that
this is due to trophoplastic invasion of the spiral arteries and their
conversion into low resistance vessels, failure of trophoplastic
invasion is associated with complications of uteroplacental
insufficiency (Papageorghiou et al., 2004).
Preeclampsia is a pregnancy specific syndrome characterized
by reduced organ perfusion secondary to vasospasm and endothelial
pathophysiology. This condition is the leading cause of maternal
Introduction and Aim of the Work
2
mortality and is responsible for considerable perinatal morbidity and
mortality (Lewis et al; 2001).
Doppler velocimetry studies of placenta and fetal circulation
can provide important information regarding fetal well being
providing an opportunity to improve foetal outcome (Serap et al.,
2003).
Pulsatility index:
A measure of the variability of blood velocity in a vessel,
equal to the difference between the peak systolic and minimum
diastolic velocities divided by the mean velocity during the cardiac
cycle abnormal MCA PI/ UA PI (CU ratio) were defined as the
ratio < 1.08 (Mosbyet al; 2009).
Doppler indices
Max = Maximum peak velocity in systole (S)
Min = Minimum peak velocity in diastole (D)
V = Venous velocity ("constant"). S/D = Svstolic: diastolic ratio
Introduction and Aim of the Work
3
Resistance index Pulsatility index
In normal pregnancy, pulsatility index decrease with
advancing gestation in Umbilical Artery. But in preeclampsia first
there is decrease diastolic flow in the Umbilical Artery due to
increase in the resistance that occurs in small arteries and arterioles
of terminal villi. As the placental insufficiency worsen, the diastolic
flow decreases, then become absent and later reverses ( Eixarch et
al; 2008).
Fetal Middle cerebral Artery (MCA) is a low resistance
circulation throughout pregnancy and accounts for 7% of cardiac
output. Increase in diastolic flow with decreased pulsatility index
shows the brain sparing taking place in fetuses of preeclamptic
patients. The ratio of PI of MCA/UA is more sensitive than MCA PI
alone in predicting adverse neonatal outcome (Gerber et al; 2006).
Doppler screening of the fetal Middle cerebral Artery wave
forms during labour can be useful in the evaluation of intrapartum
hypoxia in complicated pregnancies (Kassanos et al., 2003).
MCA/UA ratio reflects not only the circulatory insufficiency
of the Umbilical velocimetry of the placenta, manifested by
alterations in the Umbilical S/D ratio,(ratio of peak systolic blood
flow velocity) but also the adaptative changes resulting in
modification of the Middle cerebral S/D ratio (Sterne et al., 2001).
Introduction and Aim of the Work
4
(MCA/UA) ratio is a good predictor of neonatal out come and
could be used to identify fetuses at risk of morbidity and mortality in
this study they evaluated the predictive value of Umbilical Artery,
the MCA/UA ratio and the cerebral index for foetal prognosis in the
third trimester in preeclamptic women (Sterne et al., 2001).
Several studies have reported higher sensitivities and
specificities for Middle cerebral Artery, Umbilical Artery
(MCA/UA) Doppler ratio compared with Umbilical velocimetry
alone for prediction of fetal prognosis (Makhseed et al., 2000).
As a result of impaired uteroplacental blood flow,
manifestations of preeclampsia may be seen in the fetal placental
unit. These include intrauterine growth restriction (IUGR),
oligohydraminos, placental abruption, and nonreassuring fetal status
found on antepartum surveillance by Doppler ultrasound (ACOG ;
2002).
High flow resistance in the capillaries of the terminal villi
leads to low end diastolic velocity in the Umbilical Artery and
consequent hypoxia (Huppertz B. 2008)
As a result of the prolonged fetal hypoxia, circulatory
adaptation occurs in the form of cerebral vasodilatation, resulting in
the redistribution of the cardiac output to provide an adequate
oxygen supply to the brain. These changes, which help fetus to adapt
to a hostile environment, may correlate with fetal neonatal health
(Mosby et al; 2009).
Introduction and Aim of the Work
5
AIM OF THE WORK
To assess the accuracy of the Middle cerebral to Umbilical
Artery (PI) ratio in predicting fetal out come in pregnancies
complicated by preeclampsia.
Review Of Literature
6
DOPPLER ULTRASONOGRAPHY
In 1959, Satomura first described the clinical application of
Doppler ultrasound technology. In 1977 Fitzgerald and Drumm was
the first application of Doppler ultrasound in obstetrics. The simplest
type of Doppler is continuous wave (CW). Early CW transducers
were not very specific because they unable to distinguish whether
flow moved toward or away from the transducer. This deficit was
overcome with the addition of spectrum analyzers and audible
signals, which allowed estimation of frequency of the Doppler shift
and the direction of flow. In the late 1960s Pulsed wave (PW)
Doppler was introduced, which adds information on the location of a
moving target. (Gill RW et al., 1985).
Duplex Doppler imaging-PW Doppler was used in conjunction
with two-dimensional ultrasound imaging-helps guide the Doppler
sampling from ultrasound vessel visualized. Color flow mapping and
color power Doppler provide color- coded flow direction and aid in
vessel identification. Contrast agents, the most recent development,
are .increasing the signal strength to make imaging small vessels
much easier (Schleif, 1993).
Review Of Literature
7
1- Basic Principles of Doppler
Doppler Theory
The Theory and understanding of Doppler ultrasound require
an analysis of two basic physical systems. The Doppler shift
phenomena states that sound waves striking object will be returned
at a different frequency. The returning signal or sound wave
frequency should be affected by the speed and direction of the
moving object, and the distance between the origination and
reception. Doppler transducers transmit a signal of known
frequency,- capture the returning echoes, and analyze them. The
unknown are the angle of incidence and the velocity of the source,
the blood cells in the vessels, the second principle needed is that of
vector analysis (Kremkau, 1992).
The ultrasound signal strikes the red call mass and the
magnitude of the reflection is dependent on the cosine of the angle of
incidence. The velocity of ultrasound in tissue is 1540 m/second;
therefore, a correction from the frequency measurements can be
made, to summarize:
Doppler shift (FD) = Frequency reflected (FR) - Frequency at
origination (Fo)
The frequency can be equated to sound velocity in tissue and
correction made for the angle of incidence.
Review Of Literature
8
The following equation emerges:
Fr =
The optimum angle range for most studies is approximately 30ato
60° (Schulman, 1994).
Doppler Effect:
Doppler effect describes a phenomenon of perceived changes
in frequency of propagating energy waves consequent to any motion
between the source of energy emission and an observer, when the
source and observer move a part, the perceived frequency decreases,
conversely, the frequency increases when the source and observer
move closer. These changes will occur irrespective of whether the
observer or the source moves, moreover, the magnitude of the
changes in the frequency is proportional to the velocity of the
movement at the source or the receiver. This phenomenon is
applicable to all forms of energy waves, and is known as the
"Doppler frequency shift". This effect was first reported on light
waves by an Austrian mathematician, Johanna Christian Doppler in
1843 and on sound waves by (Maulik, 1997).
To date, Doppler and real-time ultrasound have not been
associated with any ill effects to fetus or mother. The U.S. food and
drug administration (PDA) guidelines state that there are no known
risks associated with use of Doppler ultrasound at the recommended
power levels. There are specific PDA guidelines for fetal ultrasound,
including that the Doppler spatial peak-temporal average-intensity
Review Of Literature
9
(SPTA) be less than 49 mw/cm2 in situ. SPTA is a unit used to
measure ultrasound energy intensity (Evans DH et al., 1989).
Doppler Equation:
In medical application, the Doppler effect is usually used by
insonating the Doppler effect moving blood and assessment of
Doppler shift of ultrasound scattered on erythrocytes. The general
methods of measurements consist of transmission of bundled
ultrasound into the body at a general angle theta (a) to the flow. The
following equation of Doppler shift is valid to sufficient
approximation (Taylor and Holland, 1990).
∆F= cos α
Where:
∆F = is the Doppler shift
Fo = is the transmitted wave frequency (usually 2-10 MH3)
V = is the velocity of the moving target
α = is the angle among the ultrasound beam and flow direction.
C = is the ultrasound propagation speed in tissues assumed to be 1
540 m/sec.
In actual clinical practice, the equation leads to the following
relationships: 1) the change in frequency is proportional to the
velocity of the movin Type equation here. g reflector, 2) The higher
the-original frequency, the greater the shift for a given velocity, 3)
The frequency increases as the reflector moves toward the transducer