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The National Ribat University

Faculty of Graduate Studies and Scientific Research

Assessment of Umbilical Artery Blood Flow Indices in Normal

Pregnancy using Ultrasonography

A Thesis Submitted in Partial Fulfillment for the Requirements of

M.Sc. Degree in Diagnostic Medical Ultrasound

By: Samah Mustafa Elawad Mohammed.

Supervisor: Dr. Ahmed Abdelrahim Mohammad Ibrahim

1439 - 2018

I

األيه

قال تعالي:

بسم ميحرلا نمحرلا هللا

متن من تأويل الحاديث ﴿ رب قد آتيتن من المل وعل

هيا ماوات والرض آهت ولي ف ادل والخرة توفن فاطر الس

الحني ﴾ مسلما وآلحقن بلص

صدق هللا العظمي

( 101سوره يوسف الايه رمق)

II

Dedication

“I wish to dedicate this work

To those who gave me to such moment my parents.

To that who gave me happiness my husband.

To those who gave me strength when I was weak my brothers and

sisters.

To those who gave me laughter when I was sad my friends.

To that who helped me my sister daughter.

III

Acknowledgement

Firstly, great thanks to Allah almighty who made all things possible and gave

me power to do such work.

I would like to extend gratitude me to my supervisor Dr. Ahmed Abdelrahim to

his vital encouragement.

I would like to thank the ultrasound unit staffs of the Department of Obstetrics

and Gynecology of Bahri teaching hospital for their kind cooperation and

valuable help

Special thanks to Dr. Zain Elabedeen Mohammad.

.

IV

Abstract

Doppler sonography is a useful tool in assessment of umbilical artery blood

flow during pregnancy.

The aim of this study was to establish a normative data of the umbilical

artery Doppler waveform indices (resistive index pulsitility index and systole to

diastole ratio) in normal fetus using ultrasonography. The problem of study was

that assessment of Doppler indices of umbilical artery become very important

to reduce perinatal mortality and morbidity.

A cross-sectional descriptive study, carried out in Khartoum Bahri hospital in

period from august to December 2017, involved 100 women with singleton

normal pregnancy between 24-40 weeks of gestation, was obtained by color

Doppler duplex ultrasound system (General electric (GE) Mindary DC-

6diagnostic ultrasound system), using Transabdominal curvilinear transducers

of (3.5-5) MHz, after fetal biometry for confirmation of gestational age,

Doppler indices measured during fetal scan. Of three measurements, the mean

average of S/D Ratio, RI and PI recorded in each gestational week, the data as

analyzed by using statistical package for social sciences.

The study found that the values of Doppler indices(S/D ratio, RI and PI)

declined gradually with gestational age. The mean values decreased from 4 to 2,

0.77 to 0.49 and 1.20 to 0.64, respectively. Notably, the Doppler indices were

less than 3, o.99 and 0.66 respectively after 31 weeks of gestation.

In conclusion, Doppler indices are more appropriate tools to assessment blood

flow of umbilical artery .The nomogram of umbilical artery Doppler waveform

indices was constructed and showed the decreasing of Doppler indices with

gestational age.

V

ملخص البحث

انظزي يفذة ف شزانه انجاث فق انصح نألرد انشزا جذ أ إطخخذاو

حمى حذفك انذو ف انشزا انظزي أثاء فخز انحم .

يؤشز يمايت ) انظزي ؤشزاث انشزا يعارت نشاء بااث إل انذراطت ذفج ذ

باطخخذاو انجاث فق يؤشز انبط ظبت االمباض نالبظاط ( ف انج انطبع ,

. حثهج يشكه انذراطت ف حمى يؤشزاث انشزا انظزي انذي أصبح يى جذا انصحت

نخمهم ي االيزاض انفاث لبم انالدة.

,أجزج ف يظخشفى انخزطو بحزي ف انفخز ب دراطت صفت يظخعزظتذ

ف )ج احذ(طبع ان حم ان يحان 011ظج . لذ 7107اغظطض ال دظبز

أطبعا ي انحم حى انحصل عها 21-72ب ي فخز انحم نفخزة انثات انثانثتا

( 5.5-5عبز انبط ) إطخخذاو انجاث فق انصح نألرد انشزا باططت

أخذ بعذ. حشخص( 6-جاس يجاث فق صح دص–. )جزال انكخزن شيغازح

الل يظح خذث لاطاث يؤشزاث انذبهز خأانجت نماص عز انحم انحتانماطاث

يؤشز انبط ظبت ,يؤشز يمايت ) انخططت نظبت تانم لاطاث،انج ي ثالثت

.حمنه انظجهت ف كم أطبع بظاط (إلمباض ناإل

شز يمايت يؤانذو ف انشزا انظزي )يؤشزاث حذفك ظبت لى جذث انذراطت أ

إخفط حخزاجع حذرجا يع عز انحم .( بظاطمباض نإلإليؤشز انبط ظبت ا

انجذز . عهى انخان (1.62انى 0 1.20انى 1.70, 7انى 5.5 )ي يخطط انمى

50عه انخان بعذ 1.66 5,1.00بانذكز أ يؤشزاث حم حذفك انذو كاج ألم ي

أطبعا ي انحم .

بانجاث فق انصحت انظزيحمى حذفك انذو ف انشزا خهصج انذراط ان أ

خطط ن حمى حذفك انذو يؤشزاث خفاضإ أ انذراط أظزث .ياطب جذا طزمت

.انحمعز ساد يع انظزي زاانش

VI

List of Contents

Content page No

ت ا I

Dedication II

Acknowledgement III

Abstract (English) IV

Abstract (Arabic) V

List of contents VI-VII

List of figures VIII

List of table IX

List of abbreviation X

CHAPTER ONE

1.1.Introduction 1

1.2. The problem of study 2

1.3. The objectives of the study 2

CHAPTER TWO

2. Literature review

2.1.Anatomy of umbilical cord 3

2.1.1Development of the umbilical cord 3

2.1.2Umbilical cord insertion 6

2.1.3Sonographic appearance of the umbilical cord 7

2.2.Anatomy and physiology of umbilical artery 8

2.3.Umbilical artery Doppler assessment 9

2.4.Umbilical artery Waveform measured 10

2.5.Doppler Parameters 12

2.6.Benefits of umbilical artery surveillance 13

2.7.Factor affect flow velocity wave form 14

2.8.The Safety of Doppler for the Obstetric Pregnancy 15

2.9. Background studies 16-18

CHAPTER THREE

3.1 Design of study 19

3.2 Sample 19

3.3 Machine 19

3.4 Method of data collection 19

3.5 Study variable 20

3.6 Method of data analysis 20

3.7 Data storage 20

3.8 Data presentation 20

3.9 Ethical consideration 20

VII

CHAPTER FOUR

4. Results 21-24

CHAPTER FIVE

5.1. Discussion 25-27

5.2. Conclusion 28

5.3. Recommendations 29

References 30

Appendices

VIII

List of figures

Figure

No.

Figure name Page

No.

2.1 Beginning of the umbilical cord. 4

2.2 Contents and development of the umbilical cord. 5

2.3 Fetus at ~53 days post-ovulation (21.5 mm crown-rump length) 6

2.4 Cross section of normal umbilical cord 6

2.5 The umbilical cord protects the fetal vessels that connect the

placenta and fetus.

7

2.6 Insertion of umbilical cord into chorionic plate. 7

2.7 Doppler ultrasound of the umbilical cord 8

2.8 Doppler waveforms at 20 and 36 weeks of pregnancy Systole (Sys)

and diastole (D) are identified

8

2.9 Normal umbilical artery Doppler ultrasound in third trimester. 9

2.10 Fluctuations in the waveform of the ductus venous due to fetal

breathing movements during vessel interrogation

10

4.1 linear relationship between the RI and GA-LMP in normal

pregnancies

21

4.2 linear relationship between the RI and FL in normal pregnancies 21

4.3 linear relationship between the PI and GA-LMP in normal

pregnancies

22

4.2 linear relationship between the PI and FL in normal pregnancies 22

4.5 linear relationship between the S/D ratio and GA-LMP in normal

pregnancies

23

4.6 linear relationship between the S/D ratio and FL in normal

pregnancies

23

4.7 variant between GA-FL (Y axis) and GA-LMP (X axis) in normal 24

IX

List of tables

Table

NO Table name Page

NO 4.1 Mean, stander deviation, minimum and maximum of the variables.

22

4.2 correlation between of RI , PI and S\D ratio in relation to GA LMP , GA FL and GA

AVG weeks 24

X

List of abbreviations

EDD

Expected Delivery Date

FL Femur length

GA Gestational Age

LMP Last menstrual period

RI Resistive Index

S/D ratio Systole to Diastole ratio

PI Pulsitility Index

0

Chapter one

Introduction

1

Chapter one

1.1 Introduction

Doppler ultrasonography is none invasive procedure that uses detectable

change in high frequency sound wave (two-twenty megahertz),based on the

Doppler effect to create clear digital image. Doppler ultrasonography has been

used as modality to measure Doppler indices (resistive index, pulsitility index

and systole to diastole ratio) of the umbilical arteries to evaluate the placental

circulation and fetal wellbeing in second and the third trimester. (1)

A basic principle of the umbilical artery waveforms, reflecting the resistance

in fetoplacental circulation, has been used extensively for fetal surveillance,

especially in high-risk pregnancy. The blood velocity waveforms in umbilical

arteries (UAs) show continuous forward flow throughout the cardiac cycle.

Absent of end diastolic flow in umbilical arteries in first trimester and high

vascular impedance detected decreased gradually with advancing pregnancy .it

is attributed to growth of placental unit and increase in the number of

functioning vascular channels. Normal umbilical artery Doppler indices

decrease gradually pulsitility index, resistive index and S/Ratio, (2 to 1), (0.8 to

5) and (5to 3) respectively. (2)

Anatomically, there are usually two umbilical arteries present together with

one of umbilical vein in umbilical cord .the umbilical arteries supply

deoxygenated blood from fetus to placenta. Inside the placenta the umbilical

arteries connect with each other’s at a distance of approximately five millimeter

to branch out intraplacental fetal arteries The umbilical artery is very important

vessel of the fetus, the first vessel to be assessed and has since become the most

widely investigated component of the fetal circulation. The unique umbilical

artery waveform can easily be detected by real time ultrasound associated with

pulse wave Doppler ultrasound (Doppler duplex system). (3)

2

It is essential that each institution should have its own baseline data to apply

to its Sudanese population in evaluation of fetal dynamic status. However, the

relationship between gestational age and Doppler waveform indices in

population has not been established. Therefore, will conduct this study to

establish a normative data of the umbilical artery Doppler waveform indices

(S/D ratio, RI and PI) in normal fetuses in second and third trimester. (3)

2.1 Problem of study:

Assessment of normal Doppler indices of umbilical artery in normal

pregnancy become very important to reduce perinatal mortality and morbidity in

high risk obstetric cases such as (intrauterine growth restriction, preeclampsia

and uteroplacental insufficiently) and this is study to evaluate normative range

of Doppler indices of umbilical artery in fetus.

3.1 Objectives:

3.1.1 General objective:

To assess of Umbilical artery blood flow indices in normal pregnancy using

ultrasonography.

3.1.2 Specific objective:

1-To measure normal umbilical artery Doppler indices (resistive index

pulsitility index and systole to diastole ratio).

2-To correlate gestational age with blood f low indices.

3-To estimate blood flow indices using gestational age.

4-To compare umbilical artery blood flow indices with international results.

2

Chapter two

Literature Review

3

Chapter two

Literature Review

2.1Anatomy of umbilical cord:

The umbilical cord is the lifeline between the fetus and placenta.it is

structure that connects the fetal circulation with the placenta. Its contains two

arteries an one vein and characteristic feature, it is helical structure, is already

developed as early as eight weeks of gestation.it is full length is usually 50-

60cm and diameter generally increase with gestational age . This particular

angioarchitecture and the surrounding Wharton’s jelly protect the blood against

compression, stretching and torsion of umbilical cord. The diameter of

umbilical artery is normally less than 2cm and develop up to 40 spiral turns as it

increase in length during gestation.(3)

2.1.1Development of the umbilical cord:

By the end of the third week of development the embryo is attached to

placenta via a connecting stalk. At approximately 25 days the yolk sac forms

and by 28 days at the level of the anterior wall of the embryo, the yolk sac is

pinched down to a vitelline duct, which is surrounded by a primitive umbilical

ring. By the end of the 5th week the primitive umbilical ring contains a

connecting stalk within which passes the allantois (primitive excretory duct),

two umbilical arteries and one vein, the vitelline duct (yolk sac stalk); and a

canal which connects the intra- and extra embryonic cavities By the 10th week

the gastrointestinal tract has developed and protrudes through the umbilical ring

to form a physiologically normal herniation into the umbilical cord. Normally

these loops of bowel retract by the end of the third month. Occasionally residual

portions of the vitelline and allantois ducts, and their associated vessels, can still

be seen even in term umbilical cords, especially if the fetal end of the cord is

examined.(3)

4

The umbilical cord normally contains two umbilical arteries and one umbilical

vein. These are embedded within a loose, proteoglycan rich matrix known as

Wharton’s jelly. This jelly has physical properties much like a polyurethane

pillow, which if you have ever tried twisting such a pillow you know is resistant

to twisting and compression. This property serves to protect the critical vascular

lifeline between the placenta and fetus. (3)

Figure2.1: Beginning of the umbilical cord. By 21 days the embryo has begun to separate from the

developing placenta by a connecting stalk. (3)

Figure 2.2: Contents and development of the umbilical cord. A, C: At 5 weeks of developing the

embryo is connected to the placenta by a stalk which contains the umbilical vessels and allantois.

Adjacent to this stalk is the yolk sac stalk which consists of the vitelline duct (yolk sac duct) and the

vitelline vessels. These structures all pass through the primitive umbilical ring. B, D: By 10 weeks of

development the yolk sac duct has been replaced by loops of bowel within the umbilical cord. (3)

5

Figure 2.3: Fetus at ~53 days post-ovulation (21.5 mm crown-rump length) showing distinct intestinal

herniation into proximal umbilical cord (arrow). Note twisting of umbilical cord (arrow head). (3)

Figure 2.4: Cross section of normal umbilical cord. Embedded within a spongy, proteoglycan rich

matrix know as Wharton’s jelly (W) is normally two arteries (A) and one vein (V). (3)

Figure2.5: The umbilical cord protects the fetal vessels that connect the placenta and fetus. A) Fetus

and placenta from a 17 week gestation. B) Diagram of the circulation within the fetus, umbilical cord

and placenta. (3)

6

2.1.2Umbilical cord insertion:

The umbilical cord normally inserts near the center of the placenta (see

Figure6). However, in approximately 7% of single births the insertion point

occurs at the very edge of the placenta (marginal insertion) and in about 1% of

cases, the umbilical cord does not insert into the placenta at all, but the fetal

vessels ramify through the external membranes before entering the placenta

(velamentous insertion). When the umbilical cord inserts into the chorionic

plate of the placenta, the fetal vessels are stabilized, and thus protected from

torsional and shear forces. On the other hand, insertion into the membranes

exposes the fetal vessels to the potential for rupture due to shearing forces or if

the vessels pass near the internal cervical os (vasa previa), by rupture due to an

ascending inflammation prior to the time of delivery . (3)

Figure2.6: Insertion of umbilical cord into chorionic plate. Normally the umbilical cord inserts near

the center of the chorionic plate, which stabilizes the fetal vessels as they leave the umbilical cord. (3)

2.1.3Sonographic appearance of the umbilical cord:

The umbilical stalk and the yolk sac are seen as early as 7 week adjacent to

the anterior abdominal wall of the developing fetus.in the second and third

trimester, the umbilical cord is readily visualized .as image in long axis, the

cord may be seen series of parallel line and shorter angled linear interface

arising from the umbilical arteries the wrap around central vein. (8)

7

Figure2.7: Doppler ultrasound of the umbilical cord. In this example the two umbilical arteries and

one vein can be easily seen within the marked off region in the center of the ultrasound image. (8)

2.2 Anatomy and physiology of umbilical artery:

The umbilical artery is a paired artery (with one for each half of the body)

that is found in the abdominal and pelvic regions. In the fetus, it extends into

the umbilical cord. (3)

The umbilical arteries supply deoxygenated blood from the fetus to

the placenta. There are usually two umbilical arteries present together with

one umbilical vein in the umbilical cord. The umbilical arteries surround

the urinary bladder and then carry all the deoxygenated blood out of the fetus

through the umbilical cord. Inside the placenta, the umbilical arteries connect

with each other at a distance of approximately 5 mm from the cord insertion in

what is called the Hyrtl anastomosis subsequently; they branch into chorionic

arteries or intraplacental fetal arteries. (3)

The umbilical arteries are actually the latter of the internal iliac

arteries (anterior division of) that supply the hind limbs with blood and nutrients

in the fetus. The umbilical arteries are one of two arteries in the human body,

that carry deoxygenated blood, the other being the pulmonary arteries. The

pressure inside the umbilical artery is approximately 50 mmHg. (3)

https://en.m.wikipedia.org/wiki/Abdominal

https://en.m.wikipedia.org/wiki/Pelvic

https://en.m.wikipedia.org/wiki/Fetus

https://en.m.wikipedia.org/wiki/Umbilical_cord

https://en.m.wikipedia.org/wiki/Venous_blood

https://en.m.wikipedia.org/wiki/Placenta

https://en.m.wikipedia.org/wiki/Umbilical_vein

https://en.m.wikipedia.org/wiki/Umbilical_cord

https://en.m.wikipedia.org/wiki/Urinary_bladder

https://en.m.wikipedia.org/wiki/Chorionic_arteries

https://en.m.wikipedia.org/wiki/Chorionic_arteries

https://en.m.wikipedia.org/wiki/Internal_iliac_arteries

https://en.m.wikipedia.org/wiki/Internal_iliac_arteries

https://en.m.wikipedia.org/wiki/Limb_(anatomy)

https://en.m.wikipedia.org/wiki/Blood

https://en.m.wikipedia.org/wiki/Fetus

https://en.m.wikipedia.org/wiki/Pulmonary_arteries

8

The umbilical artery regresses after birth. A portion obliterates to become

the medial umbilical ligament (be careful not to confuse this with the median

umbilical ligament, a different structure that represents the remnant of the

embryonic urachus). A portion remains open as a branch of the anterior division

of the internal iliac artery. The umbilical artery is found in the pelvis, and gives

rise to the superior vesicle arteries. In males, it may also give rise to the artery

to the ductus deferens which can be supplied by the inferior in some individuals.

(3)

2.3 Umbilical artery Doppler assessment:

Doppler is method by which information can be obtained by evaluating the

change in wave form in which the speed and direction of an object can be

determined.in fetal medicine we use the Doppler principle to evaluate change in

sound wave which inform us about the direction and velocity of blood flowing

through the vessels and heart .sing this technology and plotting it against time,

character of blood flow in pregnant women and fetus can be measured. (7)

The umbilical cord normally contains two umbilical arteries and one

umbilical vein .blood flow the umbilical artery originated from fetus and enter

the placenta .the flow of blood through the umbilical arteries is dependent upon

the strength of fetal heart contraction and health of placenta. Blood returning

from the placenta goes through the umbilical vein to the fetus .numerous

medical studies conducted during the past few years have found the

measurement of umbilical arteries using Doppler ultrasound in identifies high

risk fetus .when these fetuses are identified and management is altered by

physician, the fetal death rate as well as other severe complication are markedly

reduced. (7)

https://en.m.wikipedia.org/wiki/Medial_umbilical_ligament

https://en.m.wikipedia.org/wiki/Median_umbilical_ligament

https://en.m.wikipedia.org/wiki/Median_umbilical_ligament

https://en.m.wikipedia.org/wiki/Urachus

https://en.m.wikipedia.org/wiki/Internal_iliac_artery

https://en.m.wikipedia.org/wiki/Pelvis

https://en.m.wikipedia.org/wiki/Superior_vesical_arteries

https://en.m.wikipedia.org/wiki/Artery_to_the_ductus_deferens

https://en.m.wikipedia.org/wiki/Artery_to_the_ductus_deferens

9

2.4 Umbilical artery Waveform measured:

The Doppler indices measured at the fetal end, the free loop and the placental

end of the umbilical cord are different with the impedance highest at the fetal

end. The changes in the indices are likely to be seen at the fetal end first. Ideally

the measurements should be made in the free cord. However for consistency of

recording in cases being followed up, a fixed site would be more

appropriate, i.e. fetal end, placental end or intraabdominal portion. (9)

The umbilical arterial waveform usually has a "saw tooth" pattern with flow

always in the forward direction. An abnormal waveform shows absent or

reversed diastolic flow. Before the 15th week, absent diastolic flow may be a

normal finding. The 95% confidence interval limit slowly decreases for both the

resistive index (RI) and pulsitility index (PI) through the course of gestation due

to progressive maturation of the placenta and increase in the number of tertiary

stem villi. (9)

The umbilical artery is evaluated by measuring the blood flow velocity at

peak systole (maximal contraction of the heart) and peak diastole (maximal

relaxation of the heart). These values are then computed to derive a ratio. One

of the most common ratios that are used is the Resistance Index. This is

computed by measuring the peak of systole and then dividing it by the sum of

measurements at peak systole and diastole. RI= (peak systole -end

diastole)/peak systole .In early pregnancy the peak flow at diastole is less than

later in pregnancy. Therefore, as the duration of pregnancy increases, the

amount of blood flowing in the umbilical artery increases during diastole. This

means that the placenta is less resistant to blood flow, thus providing more

blood to flow from the fetus to the placenta. The following image illustrates

Doppler waveforms at 20 and 36 weeks of pregnancy. (9)

10

Figure2.8: illustrates Doppler waveforms at 20 and 36 weeks of pregnancy Systole (Sys) and diastole

(D) are identified in green Note that diastole is less at 20 weeks (yellow ellipse) than at 36 weeks (red

ellipse). (9)

Figre.2.9: Normal umbilical artery Doppler ultrasound in third trimester. (9)

2.5. Doppler Parameters:

The commonly used parameters are:

- Umbilical arterial S/D ratio (SDR): systolic velocity / diastolic velocity.

- Pulsitility index (PI) (Gosling index): (PSV - EDV) / TAV.

- Resistive index (RI) (Pourcelot index): (PSV - EDV) / PSV.

- PSV: Peak systolic velocity.

https://radiopaedia.org/articles/missing?article%5Btitle%5D=umbilical-arterial-sd-ratio

11

- EDV: End diastolic velocity.

- TAV: Time averaged velocity.(9)

The Doppler indices have been found to decline gradually with gestational age:

- S/D ratio mean value decreases from 3.560 to 2.511.

- RI mean value decreases from 0.756 to 0.609.

- PI main value decreases from 1.270 to 0.967. (9)

2.6 Benefits of umbilical artery surveillance:

Recent studies have found that surveillance of high-risk fetuses with

umbilical artery Doppler ultrasound results in a marked decrease in fetal death

and morbidity when compared to traditional surveillance (non-stress test). For

this reason, all fetuses with suspected intrauterine growth restriction should

undergo umbilical artery Doppler evaluation. (9)

2.7 Factor affect flow velocity wave form:

2.7.1 Maternal position:

During Doppler studies, the mother should lie in a semi recumbent position

with a slight lateral tilt. This minimizes the risk of developing supine

hypotension syndrome due to caval compression. (9)

2.7.2 Artifactual loss of end-diastolic frequencies:

A high angle between the ultrasound beam and the vessel results in very low

frequencies disappearing below the height of the vessel wall filter. (9)

If end-diastolic frequencies appear absent you should reduce the vessel wall

filter to its lowest setting, or remove it if possible. Then you should alter the

angle of the probe relative to the maternal abdomen to reduce the angle of

insonation. If enddiastolic frequencies are still absent you should then attempt to

obtain the signal from a different site, because this is likely to result in a

different angle of insonation. Do not report the absence of end-diastolic

frequencies until this has been demonstrated on two successive days. (9)

12

2.7.3 Fetal breathing movements:

These cause wild fluctuations in the signal from the umbilical artery and are

readily recognizable by an inability to demonstrate a steady state in the

umbilical arterial signal. The only course of action to take if the fetus is

breathing. (9)

Figure (2.10): Fluctuations in the waveform of the ductus venous due to fetal breathing

movements during vessel interrogation. (9)

2.7.4 Fetal heart rate:

There is an inverse relation between fetal heart rate and length of cardiac

cycle and, therefore, fetal heart rate influences the configuration of the arterial

Doppler waveform. When the heart rate drops, the diastolic phase of the cardiac

cycle is prolonged and the end-diastolic frequency shift declines. Although the

Doppler indices are affected by the fetal heart rate, the change is of no clinical

significance when the rate is within the normal range .Fetal bradycardia is

associated with decreased enddiastolic frequencies. When reporting Doppler

indices, you should check to ensure that the fetal heart rate is in the normal

range. (9)

2.7.5 Blood viscosity:

Previous studies have demonstrated that increased blood viscosity is

associated with reduced cardiac output and increased peripheral resistance, and

vice versa. However, Giles et al. were unable to demonstrate a significant

13

association between blood viscosity (measured in post-delivery umbilical cord

blood) and impedance to flow in the umbilical artery. (9)

2.8 The Safety of Doppler for the Obstetric Pregnancy:

Doppler ultrasound provides a noninvasive method to assess the physiology

and pathophysiology of fetal and maternal circulations when such examinations

are required for diagnosis. In most cases, pulsed wave Doppler rather than

continuous wave Doppler is used in the fetus. (9)

Doppler may be used to detect flow in the maternal vessels, the fetal vessels

(umbilical artery and vein, aorta and inferior vena cava, renal arteries, and

cerebral vessels), the fetal ductus venosus, the fetal heart, and the placenta.

Doppler interrogation is an important part of fetal echocardiography

examinations and aids in the diagnosis of fetal heart defects. Specific

applications of Doppler in obstetrics are presented in the respective chapters.

Recently, several authors have demonstrated the feasibility of examining the

fetal heart during the first trimester. Doppler is performed at a higher energy

level because these are difficult examinations that may require prolonged dwell

times, and because the embryo at this stage is small and receives total body

insonation Therefore, the use of Doppler ultrasound during the first trimester

has generated some controversy. (9)

It is the responsibility of sonographers to integrate their knowledge of

bioeffects into their scanning. In March 2008, the AIUM adopted a statement on

the As Low as Reasonably Achievable (ALARA) principle, which states the

following: The potential benefits and risks of each examination should be

considered. The ALARA (As Low As Reasonably Achievable) principle should

be observed when adjusting controls that affect the acoustical output and by

considering transducer Dwell times. (9)

14

2.9 Background studies:

In study done by Pharuhas Chanprapaph, Chanane Wanapirak and Theera

Tongsong under title Umbilical Artery Doppler Waveform Indices in Normal

pregnancies, in Thai Journal of Obstetrics and Gynecology, June 2000, Vol. 12,

pp. 103-107. A total of 332 normal singleton pregnant women were recruited

into the study from the antenatal care clinic between September 1, 1994 and

August 1, 1996. Their gestational ages were from 21 to 40 weeks. The S/D

ratio, RI and PI of the umbilical arteries were obtained by the same

sonographer. All fetuses were delivered at term with normal outcomes at birth.

Main outcome measures Means with 95% confidence intervals of the 3 Doppler

indices for each gestational week. The obtained result was the total of 411

Doppler indices measurements was performed. The values of S/D ratio, RI, PI

declined gradually with gestational age. The mean values decreased from 3.560

to 2.511, 0.756 to 0.609 and 1.270 to 0.967, respectively. Doppler indices

declined rapidly from 21 to 32 weeks, when compared to that in the last 8

weeks. Notably, the S/D ratio was less than 3 after 30 weeks of gestation. In

Conclusion the nomogram of umbilical artery Doppler waveform indices was

constructed and showed the decreasing of Doppler indices with gestational age.

These normative data could be served as a basis for evaluation the umbilical

artery circulation in Thai population.

In study done by Ganesh Acharya, Tom Wilsgaard andTorvid Kiserud under

title Reference ranges for serial measurements of umbilical artery Doppler

indices in the second half of pregnancy, American Journal of Obstetrics and

Gynecology March 2005, Vol.192(3):937–944. This was a prospective

longitudinal study of the umbilical artery Doppler indices that were obtained

serially at the free-loop of umbilical cord at 4-week intervals at 19 to 42 weeks

of gestation in 130 low-risk singleton pregnancies. A total of 513 observations

were used to construct the reference ranges with the use of multilevel

http://www.sciencedirect.com/science/journal/00029378


http://www.sciencedirect.com/science/journal/00029378/192/3

15

modelling. The obtained result was longitudinally established percentiles of

Doppler indices from the present study show a continuous reduction throughout

the second half of pregnancy without any plateau or increase near term, as

reported previously. There was a significant negative association between

Doppler indices and placental weight and neonatal birth weight, but not with

gender. The intraobserver coefficients of variation for the umbilical artery

pulsitility index, resistance index, and systolic: diastolic ratio was 10.5%, 6.8 %,

and 13.0 %, respectively. In conclusion, new reference ranges for umbilical

artery Doppler indices that are based on longitudinal observations appear to be

slightly different from cross-sectional studies and are more appropriate for serial

evaluation of fetal hemodynamic.

In study done by brian j. trudinger,warwick b. giles,colleen. ,john

bombardieriandlee collins, b. j. trudinger, department of obstetrics, university of

sydney, westmead hospital, westmead, new south wales 2145 Volume 92, Issue

January 1985 ,Pages 23–30 Australia. Under title fetal umbilical artery flow

velocity waveforms and placental resistance: clinical significance. Since the

umbilical arteries carry fetal blood to the placenta they studied flow velocity

waveforms in these vessels with a simple continuous wave Doppler system to

assess placental blood flow. The ratio of peak systolic to least diastolic (A/B)

flow velocity was measured as an index of placental flow resistance. In 15

normal pregnancies there was a small but significant decrease in this ratio

through the last trimester. The A/B ratio was measured on 436 occasions in 168

high-risk pregnancies. In 32 of 43 fetuses subsequently shown to be small for

gestational age there was an increase in placental flow resistance with reduced,

absent or even reversed flow in diastole. This finding was also present in the

one fetus which died in utero. Serial studies in patients with fetal compromise

indicated increasing flow resistance, a reverse of the normal trend. These results

were not available to the clinician yet of 24 fetuses born before 32 weeks 13 had

16

a high A/B ratio, and all of them were born electively. Maternal hypertension

was associated with an increase in fetal placental flow resistance. The umbilical

artery A/B ratio provides a new and non-invasive measure of fetoplacental

blood flow resistance.

In study done by kevin p. hanretty, mairi h. primrose, james p. neilson, martin

j.and whittle, First published:October Cited by (CrossRef):45 articlesvolume

92, issue 1 january 1985 pages 39–45 .under title Pregnancy screening by

Doppler uteroplacental and umbilical artery waveforms. 543 unselected women

attending an antenatal clinic were studied .Doppler waveforms from the

uteroplacental and umbilical arteries Overall, 357 women were studied at 26–30

weeks and 395 at 34–36 weeks; 209 were studied at both gestation periods.

Results were not made available to clinicians. There was no difference in

outcome of pregnancies between those with normal and abnormal uteroplacental

waveforms, but birth weights were significantly lower in those with an

abnormal umbilical artery waveform at either gestation. There were no other

statistically significant differences between groups. Although the power of the

study to detect differences in outcome in this sample size is limited, our findings

do not support the introduction of this new technique into clinical practice

before sufficiently large randomized controlled trials have shown some benefit.

16

Chapter Three

Materials and methods

17

Chapter Three

Materials and methods

3.1. Design of study:

A cross-sectional descriptive study deal with assessment of umbilical artery

blood flow indices in normal pregnancy using ultrasonography conducted in

Khartoum Bahri hospital in period August 2017 to November 2017.

3.2. Sample:

Asymptomatic hundreds of the normal pregnant women attended to

diagnostic ultrasound department. They were in gestational age between (24-40)

weeks. The study used the random sampling technique.

Inclusion criteria:

Consisting of normal singleton pregnancy and known definite gestational age.

Exclusion criteria:

The pregnancy with fetal anomalies, twin’s pregnancy, underlying chronic

disease and abnormal fetal growth.

3.3. Machine:

General electric (GE) Mindary DC-6diagnostic ultrasound system with 3.5-5

MHz curvilinear probe used for studying umbilical artery.

3.4. Method:

The data for this study were derived from prospective screening for adverse

obstetric outcomes in women attending to hospital for their routine follow up

which is attended at 24 to 40weeks gestation, included the recording of maternal

characteristics and medical history, and estimation of fetal size from

Transabdominal ultrasound curvilinear transducers of 3.5 MHz, measurement of

fetal head circumference, abdominal circumference and femur length.

Transabdominal color Doppler ultrasound was used to visualize the Umbilical

artery. Pulsed-wave Doppler was then used to assess impedance of flow, and

measuring of the Doppler indices (mean average of S/D Ratio, RI and PI were

18

recorded in each gestational week) measured during fetal scan by the same

examiner at the free loop site where the clearest waveform signal visualized.

3.5. Study variable:

Gestational age, femur length, LMP, resistive index, pulsitility index and S/D

ratio.

3.6. Method of data analysis:

Data were analyzed using SPSS program.

3.7 Data storage;

All data collected during the study stored on CD, personal computer, data

collection sheets and ultrasound images.

3.8. Data presentation:

The present data were in tables, figures.

3.9. Ethical consideration:

Participants informed about the plan of dissemination and publication of

research findings, also they assured that data released only after elimination of

all identifications, and verbal consent will be obtained.

18

Chapter Four

Results

19

Chapter Four

4. Results

This research aim to establish a normative data of the umbilical artery Doppler

waveform indices (resistive index pulsitility index and systole to diastole ratio)

in normal fetus using ultrasonography

The following table and figure presented the information about the variable

including gestation age, femur length, resistant indices, pulsitility indices, and

S\D ratio mean values. Correlation between gestational age with last menstrual

period ,gestational age with femur length , resistive indices ,pulsitility indices

and S/D ratio were also been presented in figures.

Table 4:1 illustrated mean, stander deviation, minimum and maximum of the variables.

Variables N Minimum Maximum Mean Std. Deviation

GA/ LMP/ weeks 100 25.00 40.00 35w4d 3.64184

GA/FL/weeks 100 24.00 40.00 34w2d 3.65301

GA/average/week 100 25.00 40.00 34w6d 3.60272

FL/cm 100 5.00 7.80 6.5900 .69856

RI 100 .49 .77 .6001 .06807

PI 100 .64 1.20 .8703 .12189

S/D ratio 100 2.00 4.00 2.6017 .48064

20

Figure 4.1: a scatter plot diagram represent linear relationship between the RI, PI, S\D ratio (Y

axis) and GA-FL (X axis) in normal pregnancies. The RI, PI, S\D ratio decreased by 0.008,

0.0129, and 0.0592 respectively as gestational age increased.


axis) and GA-AVG (X axis) in normal pregnancies. The RI, PI, S\D ratio decreased by 0.0082,

0.0131, and 0.0595 respectively as gestational age increased

RI = -0.008GA FL + 0.874

R² = 0.1841

PI = -0.0129GA FL + 1.3111

R² = 0.1487

SD ratio= -0.0592 GA FL + 4.6289

R² = 0.2022

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 5 10 15 20 25 30 35 40 45

RI

\PI

\S\D

ra

tio

GA FL weeks

RI = -0.0082 GA AVG + 0.8854 R² = 0.1858

PI = -0.0131 GA AVG + 1.3281 R² = 0.1492

S\D ratio = -0.0595 GA AVG+ 4.6853 R² = 0.1988

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 10 20 30 40 50

RI \

PI \

SD r

atio

GA AVG weeks

21


axis) and GA-LMP (X axis) in normal pregnancies. The RI, PI, S\D ratio decreased by 0.0077,

0.0124, and 0.0562 respectively as gestational age increased.

Figure 4.4: a scatter plot diagram represent variant between GA-FL (Y axis) and GA-LMP (X

axis) in normal pregnancies .the gestational age by femur length variance from gestational

age by last menstrual period by 0.979.

RI = -0.0077 GA LMP + 0.8752

R² = 0.1706

PI= -0.0124 GA LMP + 1.3135

R² = 0.1381

S\D ratio = -0.0562 GA LMP + 4.604

R² = 0.1812

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 5 10 15 20 25 30 35 40 45

RI

\OI

\S\D

ra

tio

GA LMP weeks

y = 0.979x - 0.6286 R² = 0.9525

0

5

10

15

20

25

30

35

40

45

0 10 20 30 40 50

GA

FL

GA LMP

22

Figure 4.5: a scatter plot diagram represent variant between GA-FL (Y axis) and GA-LMP (X

axis) in normal pregnancies .the gestational age by femur length variance from gestational

age by last menstrual period by 0.980.

Figure 4.6: a scatter plot diagram represent variant between GA-FL (Y axis) and GA-AVG

(X axis) in normal pregnancies .the gestational age by femur length variance from gestational

age by last menstrual period by 0.979

y = 0.9809x + 0.0274 R² = 0.9837

0

5

10

15

20

25

30

35

40

45

0 5 10 15 20 25 30 35 40 45

GA

AV

G

GA LMP

y = 0.9794x + 1.4317 R² = 0.9867

0

5

10

15

20

25

30

35

40

45

0 10 20 30 40 50

GA

AV

G

GA FL

23

Table (4.2) correlation between of RI , PI and S\D ratio in relation to GA LMP , GA FL and

GA AVG weeks

GA LMP RI PI SD GA FL GA AVG

GA LMP Pearson Correlation 1 -.413**

-.372**

-.426**

.976**

.992**

Sig. (2-tailed) .000 .000 .000 .000 .000

N 100 100 100 100 100 100

RI Pearson Correlation -.413**

1 .838**

.885**

-.429**

-.430**

Sig. (2-tailed) .000 .000 .000 .000 .000

N 100 100 100 100 100 100

PI Pearson Correlation -.372**

.838**

1 .854**

-.386**

-.386**

Sig. (2-tailed) .000 .000 .000 .000 .000

N 100 100 100 100 100 100

SD Pearson Correlation -.426**

.885**

.854**

1 -.450**

-.445**

Sig. (2-tailed) .000 .000 .000 .000 .000

N 100 100 100 100 100 100

GAFL Pearson Correlation .976**

-.429**

-.386**

-.450**

1 .993**

Sig. (2-tailed) .000 .000 .000 .000 .000

N 100 100 100 100 100 100

GA

AVG

Pearson Correlation .992**

-.430**

-.386**

-.445**

.993**

1

Sig. (2-tailed) .000 .000 .000 .000 .000

N 100 100 100 100 100 100

**. Correlation is significant at the 0.01 level (2-tailed).

23

Chapter five

Discussion, conclusion, recommendations

and references

24

Chapter five

5.1 Discussion:

This study was carried out to establish a normative data of the umbilical

artery Doppler waveform indices (resistive index pulsitility index and systole to

diastole ratio) in normal fetus using ultrasonography. This study includes 100

women with singleton normal pregnancy in 24-40 weeks of gestation.

The study found that, the higher gestational age with last menstrual period

was40 weeks and minimum gestational age was 25 weeks with mean was 35

weeks 4 days and stander deviation was 3.64. The higher gestational age by

femur length was 40 weeks and the lower gestational age 24 weeks with

mean34w2d and stander deviation 3.65. The higher femur length with was

7.8cm and lower femur length was 5cm with mean was 6.59 and stander

deviation was0.698.because as gestational age increase femur length increase

due to fetal development. The higher resistive index was 0.77 and lower

resistive index 0.49with mean was0 .6 with slandered deviation 0.068. The

higher pulsitility index was 1. 2 and lower resistive index 0.64with mean was

with 0.87 stander deviation 0.12. The higher S/D ratio was 4 and the lower S/D

ratio 2with mean was with 2.61 stander deviation 0.48.

The results of this study showed that there is an inverse linear relationship

between the RI, PI and S/D Ratio and GA-FL. The resistive index, decreased by

0.008 per week as gestational age increased, this is because of the resistance to

blood flow in the umbilical arteries falls with advances of gestation due to

continuing development of the placental vascular system throughout pregnancy.

The pulsitility index decreased by 0.0129/week as gestational age increase, this

is generally due to the facts that as gestational age increased. The resistance of

blood decreases in the fetoplacental flow resistance as a result of continuous

development of the placental vascular system in respect to time factor.

25

The S/D Ratio decreased by 0.0592/week as gestational age increased,

because as gestational age increased S/D ratio decreased due to increasing in the

end diastolic velocity. Subsequently resistance to blood flow in the umbilical

arteries falls due to continuing development of the placental vascular system

throughout pregnancy decline in the fetoplacental flow resistance.

The Study found that, there is inverse linear relationship between the RI, PI

and S\D ratio (Y axis) and GA-AVG (X axis) in normal pregnancies. The RI, PI

and S\D ratio decreased by 0.0082, 0.0131, and 0.0595 respectively as

gestational age increased this is because of the resistance to blood flow in the

umbilical arteries falls with advances of gestation due to continuing

development of the placental vascular system throughout pregnancy.

The Study found that, there is inverse linear relationship between the RI, PI,

S\D ratio (Y axis) and GA-LMP (X axis) in normal pregnancies. The RI, PI,

S\D ratio decreased by 0.0077, 0.0124, and 0.0562 respectively as gestational

age increased. This is because of the resistance to blood flow in the umbilical

arteries falls with advances of gestation due to continuing development of the

placental vascular system throughout pregnancy.

The Study found that, the estimation of GA-FL was similar to GA-LMP and

GA –average 0.976, 0.993 and 0.992 respectively.

On the other hand estimation of gestational age results indicates a good

correlation between the three estimated gestational ages although estimation

using femoral length it seem to under estimate the gestational age respectively

but still it is within the ±2 weeks limits.

The study found that, When the gestational age was 26 weeks the mean of

indices were 0.77, 1.2 and 4 respectively. When the gestational age was 28

weeks the mean of indices were 0.70, 1.0 and 3.5 respectively. When the

gestational age was 31 weeks the mean of indices were 0.66, 0.99 and 3.05

respectively. When the gestational age was 33 weeks the mean of indices were

26

0.61, 0.88 and 2.7 respectively. When the gestational age was 34 weeks the

mean of indices were 0.56, 0.81 and 2.3 respectively.

In general of the results of this study agree with previous studies which done

by (Ganesh Acharya, Tom Wilsgaard ,Torvid Pharuhas Chanprapaph, Chanane

Wanapirak and Theera Tongsong) showed that there is an inverse linear

relationship between the RI, PI S/Ratio and gestational age. Because as

gestational age increase the development of the placental vascular system

throughout pregnancy continues increase and the end diastolic velocity increase

therefor, Doppler indices (RI PI S/D ratio) decreased. But it showed minimum

variance of value of Doppler indices compared with study done by Pharuhas

Chanprapaph, Chanane Wanapirak and Theera Tongsong to for evaluation the

umbilical artery circulation in Thai population. ; This is study result (0.77-0.49)

(1, 2-0.64) (4-2) respectively. Previous study result values of RI, PI S/D ratio

was (0.756 to 0.609) (1.270 to 0.967) (3.560 to 2.511) respectively. As well it

might be due to the ethnic group because the built in equation has been

developed in a nation possesses different body characteristics than Sudanese

one.

27

5-2 conclusion:

The main objective of this study was to obtain normative data for umbilical

artery in the third trimester pregnancy.

The study found that the Doppler indices of umbilical artery range in age

group from (24-40 weeks) were 0.47-0.77, 0.64-1.2 and 2-4 for RI, PI and S/D

ratio respectively.

The normal of umbilical artery Doppler waveform indices which include; S/D

ratio, RI and PI showed a mean value of 2.61±0.48, 0.6±0.068 and 0.87±0.12

respectively.

The indices values decreases as a results of advances of gestational age i.e. in

respect to fetal development; where resistivity decrease accordingly, therefore

indices should be taken relative to gestational age.

28

5.3 Recommendations:

Assessment of umbilical artery blood flow is noninvasive exam should be

used as routine screening test in third trimester to improve the outcome.

Doppler ultrasound should be part of setup of every unit that provides

antenatal medical service with good expertise and well trained examiner.

Early screening of umbilical artery wave form should be performed to all

high risk patient this may help in early diagnosis of preeclampsia and may

decrease the maternal morbidity and mortality.

Inaccurate information concerning fetal Doppler studies may lead to

inappropriate clinical decision, it is essential that measurement be

undertaken and interpreted by expert operator who are knowledgeable

about the significance of Doppler changes and practice appropriate

techniques.

Further research should also focus on combining umbilical artery Doppler

ultrasound with other test that used in clinical care; this may improve the

predicative accuracy and the clinical important value of the tests.

29

References:

1-Sandra-L.Hagen.Ansert.Textbook of Diagnostic Sonography.7thed

.Elsevier.Mosby; California: 2012. P (1139-1166).

2-https://www.slideshare.net/mobile/drabhishekgupta9/doppler-in-

pregnancy.2september 2017

3- Harvey J. Kliman. The Umbilical Cord. The Encyclopedia of Reproduction;

Yale University School of Medicine: Sunday October 29. 2006. P (2-14).

4-Pharuhas Chanprapaph, Chanane Wanapirak and Theera Tongsong. Umbilical

Artery Doppler Waveform Indices in normal pregnancies. Journal of Obstetrics

and Gynecology; Thai :June 2000. Volume12. P (103-107).

5- Ganesh Acharya. Tom Wilsgaard and Torvid Kiserud. Reference ranges for

serial measurements of umbilical artery Doppler indices in the second half of

pregnancy. American Journal of Obstetrics and Gynecology; Elsevier: 2005.

Volume192 (3) .P (937–944).

6- Brian j. trudinger Warwick. Giles colleen. Cook john. Trudinger.

Department of obstetrics. University of Sydney; Australia Westmead hospital: 1

January 2000 .Volume 92. P (23–30).

7- Asim Kurjak. Donald School Textbook of Ultrasound in Obstetrics and

Gynecology. 3rd

edition. Jape Brothers Medical; New York: 2011.P (500-515).

8- Carol MD RumackCM. Wilsons. Charbonneau. Levine. Diagnostic

ultrasound. 4th

ed. Elsevier Mosby; Library of Congress: 2011. P (1515-1520).




23

Appendices

24

Appendix (A)

Data collection sheet

The National Ribat University

College of Graduate Studies and Scientific Research

Evaluation of Umbilical artery blood flow indices in normal

pregnancy using ultrasonography

NO Gestational

age LMP

GA -FL GA Average PI RI S/D

ratio

25

Appendix (B)

Ultrasound images

image no1:show normal umbilical artery velocity.spectrial doppler of the UA in third

trimester(31week)show an arterial waveform with forward flow throughout the cardic cycle and

relatively high end diastolic flow resulting in low dopler indices.RI=0.71 PI=1 S/D=3.4.

image no 2:show normal umbilical artery velocity.spectrial doppler of the UA in third

trimester(32week)show an arterial waveform with forward flow throughout the cardic cycle and

relatively high end diastolic flow resulting in low dopler indices.RI=0.63 PI=0.94 S/D=3.

26


trimester(37week)show an arterial waveform with forward flow throughout the cardic cycle

and relatively high end diastolic flow resulting in low dopler indices.RI=0.64 PI=0.94

S/D=2.7.



and relatively high end diastolic flow resulting in low dopler indices.RI=0.51 PI=0.68 S/D=2.

27

Image no 5:show normal umbilical artery velocity.spectrial doppler of the UA in third



S/D=2.1.



and relatively high end diastolic flow resulting in low dopler indices.RI=0.53 PI=1 S/D=3

28




S/D=2.7.




S/D=2.7.

29

.




S/D=2.1.




S/D=2.8.

30

Image no11:show normal umbilical artery velocity.spectrial doppler of the UA in third





and relatively high end diastolic flow resulting in low dopler indices.RI=0.69 PI=1 S/D=3.2.

31

Image No13:show normal umbilical artery velocity.spectrial doppler of the UA in third



S/D=3.




S/D=2.8.

32

`

Image No 15:show normal umbilical artery velocity.spectrial doppler of the UA in third



S/D=2.8.

Image No16:show normal umbilical artery velocity.spectrial doppler of the UA in third



33




S/D=2.5.




S/D=2.8.

34




S/D=3.3.




S/D=2.5.

35







36



and relatively hig h end diastolic flow resulting in low dopler indices.RI=0.64 PI=0.96

S/D=2.8.

.



and relatively high end diastolic flow resulting in low dopler indices.RI=0.67 PI=1

S/D=3.07.

37




S/D=2.47.




S/Dratio=2.

38




S/Dratio=2.4.


trimester (34week)show an arterial waveform with forward flow throughout the cardic cycle


S/D=2.2.

39

Appendix No22:show normal umbilical artery velocity.spectrial doppler of the UA in third



S/Dratio=2.1.

Appendix No30:show normal umbilical artery velocity.spectrial doppler of the UA in third


and relatively high end diastolic flow resulting in low dopler indices.RI=0.95 PI=1

S/Dratio=2.8.

40

Appendix (c)

Table (5.1) compare mean for measurement of RI, PI and S\D ratio in relation to GA LMP weeks.

GA b LMP RI PI SD

25 Mean .6500 1.0000 3.2000

26 Mean .7700 1.2000 4.0000

27 Mean .6700 .9667 3.1000

Std. Deviation .05196 .05774 .45826

28 Mean .7000 1.0000 3.5000

29 Mean .6367 .9400 2.9000

Std. Deviation .04726 .06557 .36056

30 Mean .6000 .8500 2.4000

31 Mean .6650 .9950 3.0500

Std. Deviation .02121 .00707 .07071

32 Mean .6120 .8940 2.6000

Std. Deviation .03899 .05639 .18708

33 Mean .6191 .8845 2.7182

Std. Deviation .07803 .15267 .56182

34 Mean .5650 .8150 2.3000

Std. Deviation .06403 .05972 .25820

35 Mean .6200 .9433 2.8167

Std. Deviation .06573 .07633 .44907

36 Mean .5930 .8560 2.5600

Std. Deviation .06832 .12030 .53996

37 Mean .6125 .8850 2.6481

Std. Deviation .05698 .11679 .41584

38 Mean .5533 .7683 2.2750

Std. Deviation .07127 .12097 .42239

39 Mean .5858 .8300 2.4583

Std. Deviation .05518 .11144 .34234

40 Mean .5658 .8542 2.4333

Std. Deviation .06127 .10405 .41851

Total Mean .6001 .8703 2.6017

N 100 100 100

Std. Deviation .06807 .12189 .48064

41

Table (5.2) compare mean for measurement of RI, PI and S\D ratio in relation to GA FL weeks.

GA FL RI PI SD

24 Mean .7700 1.2000 4.0000

25 Mean .6533 .9667 3.1000

Std. Deviation .04509 .05774 .45826

26 Mean .7000 1.0000 3.3500

Std. Deviation .00000 .00000 .21213

27 Mean .6900 1.0000 3.2000

28 Mean .6000 .8600 2.4500

29 Mean .6200 .9500 3.0000

30 Mean .6467 .9400 2.8333

Std. Deviation .02887 .05292 .23094

31 Mean .6329 .9343 2.8143

Std. Deviation .07342 .14853 .50143

32

Mean .5887 .8300 2.4875

Std. Deviation .07019 .10850 .53033

33 Mean .6017 .8667 2.7000

33 w2d Mean .6500 .9500 2.8000

33w3d Mean .6500 .9600 2.8000

34 Mean .6188 .9075 2.7500

Std. Deviation .07396 .13221 .58064

35 Mean .5910 .8850 2.5400

Std. Deviation .05587 .10384 .41687

35w5d Mean .6700 1.0000 3.0700

36 Mean .5714 .8150 2.4071

Std. Deviation .07843 .13883 .49531

37 Mean .5853 .8093 2.4333

Std. Deviation .05668 .10694 .33523

38 Mean .5686 .8843 2.4714

Std. Deviation .04981 .09641 .35456

38w3d Mean .5600 .7700 2.2000

38w5d Mean .6000 .9000 2.5000

39 Mean .5600 .7750 2.4000

Std. Deviation .10100 .15000 .66833

39w5d Mean .5900 .8300 2.4000

40 Mean .5500 .8500 2.2500

Std. Deviation .07071 .07071 .35355

Total Mean .6001 .8703 2.6017

Std. Deviation .06807 .12189 .48064

42

Table (5.3) compare mean for measurement of RI, PI and S\D ratio in relation to GA-AVG weeks.

GA AVG RI PI SD

25 Mean .7100 1.1000 3.6000

Std. Deviation .08485 .14142 .56569

26 Mean .6550 .9500 3.0500

Std. Deviation .06364 .07071 .63640

27 Mean .7000 1.0000 3.5000

28 Mean .6900 1.0000 3.2000

28w5d Mean .6000 .8700 2.5000

29 Mean .6100 .9000 2.7000

Std. Deviation .01414 .07071 .42426

30w5d Mean .6800 1.0000 3.1000

31 Mean .6367 .9367 2.8000

Std. Deviation .01155 .04726 .17321

31w5d Mean .5750 .8500 2.4000

Std. Deviation .03536 .07071 .00000

32 Mean .6575 .9625 2.9750

Std. Deviation .08500 .18875 .58523

32w5d Mean .6200 .8780 2.7400

Std. Deviation .06856 .12418 .55946

33 Mean .5980 .8480 2.4200

Std. Deviation .04712 .06723 .26833

33w5d Mean .5000 .7300 2.1000

Std. Deviation 0.000 0.04243 0.14142

34 Mean .6325 .9150 2.9250

Std. Deviation .02363 .08062 .22174

34w5d Mean .5950 1.0000 2.6000

Std. Deviation .13435 .00000 .84853

35 Mean .6267 .8767 2.8000

Std. Deviation .06121 .14109 .56214

35w5d Mean .5700 .8900 2.4000

Std. Deviation .05657 .01414 .14142

36 Mean .5825 .8575 2.4725

Std. Deviation .06468 .12563 .48672

36w5d Mean .6533 .9667 2.9667

Std. Deviation .00577 .03055 .05774

37 Mean .5791 .7982 2.4182

Std. Deviation .08031 .13423 .44681

37w5d Mean .5550 .7500 2.2000

Std. Deviation .04950 .07071 .28284

38 Mean .5755 .8073 2.4000

Std. Deviation .05592 .11118 .35496

38w5d Mean .5800 .8367 2.4000

Std. Deviation .07211 .13051 .40000

39 Mean .5643 .8786 2.4429

Std. Deviation .03952 .08275 .31015

39w5d Mean .5800 .8000 2.5333

Std. Deviation .11358 .17321 .75056

40 Mean .5500 .8500 2.2500

Std. Deviation .07071 .07071 .35355

Total Mean .6001 .8703 2.6017

Std. Deviation .06807 .12189 .48064

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