national ribat university college of graduate studies...

National Ribat University

College of Graduate Studies

Sonographic Assessment of Gestational Age Using Transverse Cerebellum Diameter

A thesis Submitted for Partial Fulfillment of Requirement of the MSc

Degree in Medical Diagnostic Ultrasound

By: Rawan Ismail Ali Ismail

Supervisor: DR. Elsir Ali Saeed Taha

2017

اآلية

بسم هللا الرحمن الرحيم

يؤتى ٱلحكمة من يشاء ومن يؤت ٱلحكمة فقد أوتى )

ب خيرا كثيرا وما يذكر إل (أولوا ٱللب

(269البقرة )

Dedication

Every challenging work needs self-effort as well as guidance

of elders' especially those who were close to our heart.

My humble effort I dedicate to:

My sweet and loving

Mother & father,

Whose prays of day and night, taught me to trust in Allah,

believe in hard work and that so much could be done with

little.

MY brothers and sisters:

Whose affection, love, encouragement, makes me able to get

such success.

Acknowledgement

Gratefully, I like to thanks God for giving me the strength to finish this

research successfully, and also I would like to express the deepest gratitude

to following that without their help, this research would not possible:

Firstly I would like to thanks my supervisor DR. Elsir Ali Saeed Taha for his

great help, support and motivation, and for providing comments, discussion

and guidance over study.

My thanks also should go to all staff members of Ultrasound department in

Shifa Alalil Hospital and Salah Medical center.

I would like to express my sincere gratitude to DR.Awadia Greeb Allah

collage of medical Radiological sciences, in AL Zaiem Al Azhari University

who she helped in the statistical analysis of the results and endless help and

encouragement that built confidence in my work.

And lastly thanks to anyone who contributed, directly or indirectly to this

work.

Thank you very much

Abstract

Cross-sectional descriptive study was conducted at Shifa AL Aliel Modern

Medical Hospital Omdurman, and some private centers during a period from

August 2016-October 2016. Biparietal diameter and the femur length

decreased as pregnancy progress due to increasing biological variation. The

objective of this study was to measure and correlate transverse cerebellar

diameter with fetal gestational age as an alternative parameter to estimate

gestational age in second and third trimesters of pregnancy.

The study included 104 singleton normal pregnancies; all were scanned

using standard ultrasound scanning. Fetal biometry Biparital diameters

(BPD), femur length (FL), transverse cerebellar diameter (TCD) were

assessed. Data was collected in the data collection sheet. Estimation of

gestational age was based on the last menstrual period and fetal ultrasound.

The data was analyzed using the Statistical Package for Social Sciences.

The results showed that there were liner relationship between transverse

cerebellar diameter (TCD) measurement in mm and average gestational age

per weeks R2 =0.9696 p≤ 0.000.

The study conduct that the transverse cerebellar diameter can be used as

reliable parameter in the estimation of fetal gestational age in second and

third trimesters of pregnancy. The study recommend further studies should

be performed with taking large sample volume size to establish chart for

measurement of gestational age weeks by transverse cerebellum diameter for

Sudanese pregnant women.

ملخص الدراسة

العليل الطبي الحديث هذه دراسة عرضية وصفية مقطعية أجريت في مستشفي شفاء

.2016اكتوبر -2016امدرمان وبعض المراكز الخاصه في الفترة من اغسطس

قطر المخيخ عرضيا كعامل بديل ستخدامهدفت هذه الدراسة لقياس وربط عمر الجنين بإ

لتقدير عمر الجنين في الثلث الثاني والثالث من الحمل.

بالموجات فوق الصوتية. حمل مفرد طبيعي. تم فحصهم 104شملت الدراسه

تم تقيم قياسات األجنة الحيوية وتشمل قطر العظم الجداري, وطول الفخذ و قطر المخيخ

عرضيا. وتم تسجيلهم في ورقة جمع البيانات.

تم االعتماد علي تقدير عمر الجنين علي اخر موعد للدورة الشهرية وبعدها قياس

الموجات فوق الصوتية.

المستخدمة بواسطه برنامج الحزم اإلحصائية للعلوم االجتماعية.تم تحليل البيانات

واظهرت النتائج أن هنالك عالقه خطية بين قياس قطر المخيخ عرضيا بإلملميتر و

(. P≤ 0.000) 2R 0.9696=متوسط عمر الجنين باالسابيع

وخلصت الدراسة الي ان قياس قطر المخيخ عرضيا يمكن االعتماد عليه كمعطي

يستخدم في تقدير عمر الجنين في الثلث الثاني والثالث من الحمل.

اوصت الدراسة بعمل دراسات اخري مع استخدام عينات كبيرة ألنشاء جدول لقياس

عمر الجنين باالسابيع مع قياس المخيخ عرضيا لدي النساء الحوامل السودانيات.

Tables of Contents

Topic

Page

Number

Quraan

I

Dedication

II

Acknowledgement

III

English Abstract

IV

Arabic Abstract

V

Table of contents

VI

List of Table

X

List of Figures

XI

Table of Abbreviation

XIII

Chapter one

Introduction

1.1 Introduction

1

1.2 problem and Justification

2

1.3 Objectives

2

1.4 hypothesis of study

3

Chapter Two

Literature Review and background studies

2.1 Anatomy

4

2.2 Anomalies of posterior fossa and cerebellum

6

2.2.1 Dandy – Walker malformation

6

2.2.2 Rhombencephalosynapsis

7

2.2.3 Mega-Cisterna magna

7

2.2.4 Arachnoid cysts

8

2.3 Estimation of gestational age in second and

third trimester

9

2.3.1 Clinical dating

9

2.3.2 Sonographic estimation of gestational age in

second and third trimester

10

2.3.2.1 Fetal head measurements

10

1 Biparaietal diameter

10

2 Occipitofrontal diameter

11

3 Head circumference

12

4 Cephalic index

13

5 Corrected-BPD

13

6 Transverse cerebellum diameter

14

2 Bones length measurements

15

1 Femur length

15

2 Tibia and fibula length

16

3 Humeral length

16

4 Radius and ulna length

17

4 Abdominal circumference

16

2.3.2.4 Composite dating

18

2.4 Previous studies

19

Chapter three

Material and Methods

3.1 study Design

22

3.2 Study Area

22

3.3. Study Duration

22

3.4 Study Population

22

3.5 Inclusion criteria of the study

22

3.6 Exclusion criteria of the study

22

3.7 Data collection tools

23

3.8 Data Analysis

24

3.9 Ethical consideration

24

Chapter four

Results

Results and Analysis

26

Chapter five

Discussion, Conclusion and Recommendations

5.1 Discussion

34

5.2 Conclusion

37

5.3 Recommendations

38

References

39

Appendices

List of Tables

Table NO.

Title Page

4-1

Average gestational age per weeks, BPD, FL and TCD

24

4-2

Measurement per mm BPD,FL and TCD

24

4-3

Frequency distribution of Average gestational age

group

27

4-4

Minimum, maximum, means and STD of gestational

age group ( 14-20 weeks)

27

4-5


age ( 20 weeks+1day-30weeks)

27

4-6


age (30 weeks+1 day-40)

27

4-7

Correlation between TCD in mm with GA by BPD,

FL, TCD and with average GA

33

List of Figures

Figure

NO. Title Page

2-1

Three areas of the primitive brain

4

2-2

Schematic of the embryonic development of

the brain

6

2-3

Fetus with Dandy-Walker malformation at 24

weeks

7

2-4

Mega-Cisterna magna (measured 11 mm),

and cerebellar hypoplasia at 25 weeks

8

2-5

Archnoid cyst in supratentorial,

interhemispheric position at 25 weeks

8

2-6

Biparital diameter (BPD) and occipitofrontal

diameter (OFD) measurements

12

2-7

Transverse cerebellum diameter (TCD)

15

2-8

Fetal femur length measurement

16

2-9

Abdominal circumference measurement

18

3-1

Show electronic calipers place in TCD

measurement

24

4-1

Shows correlation between gestational age by

TCD per week and average gestational age

28

per week

4-2

Shows correlation between GA by BPD in

week and avarage gestational age per weeks

28

4-3

Shows correlation between GA by FL in

week and avarage gestational age per weeks

29

4-4

Shows correlation between TCD

measurement in mm and avarage gestational

age per weeks

29

4-5


measurement in mm and average gestational

age per weeks

30

4-6


measurement in mm and gestational age by

FL per weeks

30

4-7


measurement in mm and gestational age by

BPD per weeks

31

4-8


measurement in mm and measurement of

BPD per mm

31

4-9


measurement in mm and measurement of FL

per mm

32

4-10

Shows correlation between GA by TCD in

week and GA by BPD in weeks

32

4-11

Shows correlation between GA by TCD in

week and GA by FL in weeks

33

List of Abbreviations

Abbreviations

AC

Abdominal circumference

AIUM

American Institute of Ultrasound in Medical

BPD

Bipariteal diameter

CI

Cephalic index

d

Day

EDC

Expected data of delivery

EDD

Estimated data of delivery

Fig

Figur

FL

Femur length

GA

Gestational age

HC

Head circumference

IUGR

Intrauterine Growth Restriction

LMP

Last menstrual period

mm

Millimeter

OB

Obstetric

OFD

Occiptofrontal diameter

SD/Std

Stander deviation

TCD

Transverse cerebellar diameter or Transverse

cerebellum diameter

Wks

Week

Chapter One

Introduction

Chapter One

Introduction

1.1 Introduction

The cerebellum, the largest part of hind brain, lies in the posterior cranial

fossa. It lies dorsal to the pons and the medulla, separated from them by the

fourth ventricle .cerebellum is separated from the cerebrum by a fold of

duramater called the tentorium cerebelli. The cerebellum consists of a

midline part called the vermis and two lateral hemispheres it is roughly

spherical but somewhat constricted in it is median region and flattened, the

greatest diameter being transvers. (1)

The cerebellum develops from the dorsolateral part of the alar lamina of the

metencephalon. In the embryo cerebellum appears at the end of the fifth

week as a swelling overriding the fourth ventricle. (2)

Assessment of fetal gestational age (GA) is an essential part of obstetric

ultrasonography, it important in the management of pregnancy and

evaluation of fetal growth. The most frequently used biometric parameter for

estimation of gestational age in second and third trimester are the fetal

biparietal diameter (BPD), head circumference (HC), abdominal

circumference (AC) and femur length (FL). These parameters have few

limitations as condition altering the shape of skull will affect the BPD which

is well accepted indicator of GA. Femur length (FL) varies somewhat with

ethnicity. Short femurs are commonly a normal variant however this finding

may also indicate fetal growth restriction, aneuploidy, and when severely

shortened skeletal dysplasia. Transverse cerebellum diameter (TCD)

developed as an alternative parameter of fetal brain growth and estimation of

gestational age. (3, 4)

Since cerebellum lies in posterior cranial fossa, surrounded by the dense

petrous ridge and the occipital bone so it can withstand deformation by

extrinsic pressure better than the parietal bones and it is not influence by

alteration in fetal growth such as macrosomia and intra uterine growth

retardation, the fetal cerebellum can be visualized with ultrasound easily

therefore imaging the posterior fossa is becoming an integral part of many

routine fetal sonogram. (3)

TCD can be used as a reliable parameter for estimation of fetal gestational

age compared to other routine parameter. It is observed that fetal TCD

correlates well with fetal growth indices. Obstetric ultrasound non-invasive,

cost effective, easily available, can be used for imaging fetal cerebellum.

TCD can be better marker for gestational age estimation. (5)

1.2 problem and Justification

It important to estimation of fetal gestational age for management of

pregnancy, the accuracy of the biparietal (BPD) and the femur length (FL)

decreased as pregnancy progress due to increasing biological variation, this

study has been done to detect the accuracy of transverse cerebellum diameter

(TCD) as an alternative parameter to determine the fetal gestational age in

second and third trimester by using gray scale ultrasound.

1.3 Objectives

1.3.1 General objective

To assess the gestational age using the transverse cerebellum diameter using

gray scale ultrasound in second and third trimester of pregnancy.

1.3.2 Specific objective

To determine the average gestational age using LMP and TCD.

To compare between the gestational age by transverse cerebellum diameter

and average gestational age.

To compare between gestational age by transverse cerebellum diameter,

BPD and FL.

1.4 hypothesis of study

There is a good correlation between the fetal gestational age and Transverse

cerebellum diameter so TCD measurement can use as reliable parameter to

estimate gestational age in second and third trimester.

Chapter Two

Literature Review and

Background studies

Chapter Two

Literature Review and

Background studies

2.1 Anatomy

Central nervous system development starts at about the fifth menstrual

weeks, when cells destined to form the notochord infiltrate into the

embryonic disc. This notochord infiltrate into the embryonic disc. This

notochord tissue induces overlying embryonic tissue to thicken and

ultimately fold over and fuse as neutral tube. The fusion starts in the

midtrunk of embryo and subsequently extends to the cranial and caudal

ends. The brain develops at the cranial ends of the neural tube; there are

three distinct area of development prosencephalon or forebrain,

mesencephalon or midbrain and rhombencephalon or hindbrain. (6, 7)

Figure (2-1) Three areas of the primitive brain. (7)

The anterior end, the rostral neuropore, closes by about 51/2 menstrual

weeks, and caudal end close about ½ weeks later.

By the sixth week, the cephalic end enlarged and flexes to become the brain.

By 12 to 15 menstrual weeks, almost all structures are in their final form.

Exceptions are the corpus callosum, cerebellar vermis, and neural migration

from the periventricular germinal matrix, development of sulci and gyri, and

myelination. These later structures and processes start developing from

about 15 weeks onward. The corpus callous induces the formation of the two

septi pellucidi and the intervening space, which is the cavum septi pellucidi

and cavum vergae. The cerebellum and vermis develop as proliferations into

the cephalic part of a thin dorsal membrane (area membranacea), that forms

the dorsal aspect of the rhombencephalic neural tube. The enclosed part of

the hindbrain neural tube is the rhombencephalic cavity. (6)

The cerebellar development starts at about 6 to 7 weeks of gestation, and the

final gross form is achieved by about 18 to 20 weeks. Cerebellar components

continue to develop to about 7 months after birth, and final neuronal

organization continues to about 20 months after delivery. The cerebellum

develops as thickenings of lateral rhombic lips, which enlarge posteriorly

and are joined in midline by the vermis, which develops from the rostral

aspect. These thickenings grow into the thin membranous dorsal aspect of

the neural tube, the area membranancea, which is rhombencephalic cyst that

is prominent in early pregnancy and later becomes the fourth ventricle and

fenestrates, forming the foramina of Magendie and Luschka. (6)

Cerebellum is composed of two lateral cerebellar hemispheres connected in

the midline by a structure called the vermis. The surface of the cerebellum

consists of a thin cortex of gray matter. The cortex dips deeply below the

apparent surface of the cerebellum in a manner similar to the fissures and

sulci of the cerebrum, although the cerebellar indentations are more parallel,

giving the appearance of a series of flattened plates. The cerebellum is a

well-defined, easily evaluated structure with ultrasound in the second and

third trimester.

The cerebellum is best visualized with an appropriate oblique scan of the

posterior fossa. The paired cerebellar hemispheres are less echogenic than

the vermis. (7)

Figure (2-2) Schematic of the embryonic development of the brain. (8)

Cerebellum receives input from sensory system of spinal cord and from

other parts of the brain, and integrates these inputs to fine-tune motor

activity. Cerebellum damage produces disorder in fine movement,

equilibrium, posture and motor learning.

2.2 Anomalies of posterior fossa and cerebellum

Abnormal cerebellar development is often accompanied by developmental

and functional changes in cerebral cortex and other parts of the body.

Functionally, the cerebellum not only controls voluntary movements but is

also involved in non-motor and cognitive functions function.

A large spectrum of abnormalities involves the cerebellum and posterior

fossa, these including:

2.2.1 Dandy – Walker malformation

Dandy-Walker malformation is defect that may have varying degree of

severity. It manifests with agenesis or hypoplasia of the cerebellar vermis

with resulting dilatation on the fourth ventricle and enlargement of the

posterior fossa. (8)

DWM is frequently associated with other CNS abnormalities including

hydrocephalus (~80% of cases) and agenesis of the corpus callosum (~20%

of cases). The prognosis of Dandy-Walker malformation depends on

associated abnormalities. Those with isolated findings do better, but

outcomes are poor in those with associated somatic abnormalities.

The key sonographic feature of DWM is a posterior fossa cyst of variable

size with evidence of vermian agenesis. (7)

Dandy-Walker variant is characterized by partial vermian agenesis and a

smaller posterior fossa cyst.

Figure (2-3) Fetus with Dandy-Walker malformation at 24 weeks. (6)

2.2.2 Rhombencephalosynapsis

Is rare hypoplasia of the cerebellum characterized by complete or partial

absence of the vermis and fusion of the cerebellar hemispheres and dentate

nuclei. The defining findings at ultrasound are small, bean-shaped

cerebellum that lacks the typical echogenic narrowing at vermis and

cerebellar hemispheric fissures, which are continuous from side to side

without midline interruption. (6)

2.2.3 Mega-Cisterna magna

Refers to enlargement of the cisterna magna beyond 10 mm with intact

vermis. This is an isolated finding, almost all fetuses are normal. However,

if not isolated, only 11% have normal outcome. (6)

Figure (2-4) Mega-Cisterna magna (measured 11 mm), and cerebellar

hypoplasia at 25 weeks. (6)

2.2.4 Arachnoid cysts

Arachnoid cysts are benign, non-communicating fluid collections within

arachnoid membranes. Most appear stable and require no surgical treatment.

Locations by order of frequency are sylvian fissure or temporal fossa,

posterior fossa, over the cerebral convexity, and midline supratentorial. Even

very large arachnoid cysts rarely cause symptoms. (6)

Figure (2-5) Archnoid cyst in supratentorial, interhemispheric position at

25 weeks. (6)

2.3 Estimation of fetal gestational age in the second and third trimester

Accurate knowledge of gestational age is important for a number of reasons.

The timing of chorionic villus sampling and screening tests in the first

trimester, genetic amniocentesis in the second trimester, and elective

induction or cesarean delivery in the third trimester are all based on the gestational age.

The differentiation between term and preterm labor and the characterization of a

fetus as “postdates” depend on gestational age. Knowledge of the gestational

age can be critical in distinguishing, normal from pathologic fetal

development. (6)

2.3.1 Clinical dating

The average duration of pregnancy is 280 days from the first day of last

menstrual period or 266 days from ovulation, based on the 28-day cycle. By

convention, the duration of pregnancy is based on menstrual dates, with the

first day of last LMP being the point reference. In women with regular 28

day cycle, ovulation and conception occurs approximately 14 days after

LMP. Embryonic or fetal age begins at conception (conceptual age) and the

term of reference for describing embryologic development by embryologist.

A quick method of determining the Expected Date of Confinement (EDC)

or due date is use Nagele's Rule: to the first day of the LMP, add 7 days,

subtract 3 months, and add 1 year, or alternately, add 9 months and 7days. (7)

The length of pregnancy increases about 1 day for each day the menstrual

cycle is more than 28 days.

2.3.2 Sonographic estimation of gestational age

Many sonographic parameters have been proposed for estimating

gestational age in the second and third trimester. These include several fetal

measurements: biparietal diameter (BPD), head circumference (HC),

transverse cerebellum diameter (TCD), abdominal circumference (AC),

femur length (FL), length of other long bones, binocular distance as well as

combinations of two or more fetal measurement : the corrected –BPD and

composite age formulas. Measurements of abnormal structure fetal body

parts should not be used in the assignment of gestational age. (6)

2.3.2.1 Fetal head measurements

1 Biparaietal diameter

In the second trimester, the biparietal diameter (BPD) was the first and is the

most widely accepted means of measuring the fetal head and estimating fetal

age. As the pregnancy enters the third trimester, an accurate measurement of

fetal age becomes more difficult to obtain because the fetus begins to drop

into the pelvic outlet cavity. The reproducibility of the BPD is±1mm (±2

standard deviations). When dating a pregnancy between 17 and 26 weeks of

gestation, the predictive value is±11 days in 95% of the population. After

26 weeks, the correlation of BPD with gestational age decrease, because of

the increased biologic variability. The predictive value decreases to±3

weeks in the third trimester. The growth of the fetal skull slows from 3 mm

per week in the second trimester to 1.8 mm per week in the third trimester.(8)

When measuring the BPD, it is important to determine, the landmarks

accurately. The fetal head should be imaged in a transverse axial section,

ideally with the fetus in a direct occiput transverse position. The BPD should

be measured perpendicular to the fetal skull at the level of the thalamus and

the cavum septi pellucidi. Intracranial landmarks should include the falx

cerebri anteriorly and posteriorly, the cavum septi pellucidi anteriorly in the

midline, and the choroid plexus in the atrium of each lateral ventricle. With

real-time sonography, one can identify the middle cerebral artery pulsating

in the insula; the head shape should be ovoid, not round (brachycephaly),

because this can lead to over estimation of gestational age, just as flattened

or compressed head (dolichocephaly) can lead to under estimation of

gestational age estimated from the BPD measurement. The calipers should

be placed at the outer edge of near calvarial wall to the inner edge of

calvarial wall; the cerebellar hemispheres should not be in the plane of the

image. (8, 9)

2 Occipitofrontal diameter

The occipitofrontal diameter (OFD) may be used as an alternative

measurement if the BPD is unsatisfactory because of low fetal head position.

Several data for OFD measurements against gestational age have been

published. The main use of the OFD is to determine head circumference

from the ellipse formula when there is no tracing calipers and determination

of the cephalic index (CI), OFD obtained from the same transaxial image as

the BPD and it measured from midskull to midskull along the long axis of

the fetal head. (6, 7)

Figure (2-6) Biparietal diameter (BPD) and occipitofrontal diameter (OFD)

measurements. (6)

3 Head Circumference

Prenatal compression of the fetal skull is common. It occurs more often in

fetal malpresentation, such as breech, or in conditions of intrauterine

crowding, such as multiple pregnancies. The fetal skull can also be

compressed in vertex presentations without any obvious reason or as a result

of an associated uterine abnormality, such as leiomyoma. The transverse

head circumference (HC) is less affected than BPD by head compression, so

the HC is a valuable tool in assessing gestational age. (8) HC is length of the

outer perimeter of the skull made from the BPD image. The HC can be

measured with electronic tracing elliptical calipers that allow the HC to be

calculated electronically or it may be computed by obtaining the appropriate

transverse and occipitofrontal diameter by using the following formula:

HC (cm) =BPDO-to-O (cm) + OFD O-to-O (cm) × 1.57

Where, BPDo-to-o is the outer-to-outer biparietal diameter

OFDo-to-o is the outer-to-outer occipitofrontal diameter

1.57 is a mathematical constant (one-half of 𝜋 )

HC measurements are independent of the shape of the skull and are

therefore not influenced by head shape variations such as dolicocephaly and

brachycephaly. (7)

4 Cephalic Index

Two frequently noted alterations in head shape are dolichocephaly and

brachycephaly. In dolichocephaly, the head is shortened in the transverse

plane (BPD) and elongated in the anteroposterior plane (OFD). In

brachycephaly the head is elongated in the transverse diameter (BPD) and

shortened in the anteroposterior diameter (OFD). One can under estimate

gestational age from adolichocephalic head or over estimate with

brachycephaly. Cephalic index (CI) is ratio of transverse head diameter

(outer-to-outer BPD) and outer- to-outer OFD stands from occipitofrontal

diameter. CI has a normal range which is effectively independent of

gestational age. The normal range for CI is 0.70 to 0.86 or 70 to 86 (2SD). If

the measured CI falls within the normal range, this indicates a normal ratio

between the transverse and occipitofrontal diameters. When the CI falls

within the normal range, the BPD remains an acceptable parameter to

estimate fetal age. If the CI falls outside the normal range, the BPD should

not be used to estimate gestational age. (7, 8)

5 Corrected-BPD

Corrected-BPD is a formula-adjusted BPD value based on a formula that

incorporates the BPD and OFD values and accounts for variations in head

shape. The corrected-BPD formula is based on the standard shape of a fetal

head which has an OFD to BPD ratio of 1.265 (OFD is 26.5% greater than

the BPD (this ratio is based on a mean CI value of 0.78 or 78) For the

corrected-BPD measurement, the BPD is measured in the standard fashion

(O-to-I), and the OFD is measured midskull-to-midskull (not O-to-O). The

corrected- BPD is an alternative technique to HC measurements. The same

tables used to determine gestational age from the standard BPD are used to

estimate gestational age from the corrected- BPD. HC measurements appear

to be more popular than corrected-BPD although both approaches have

equal merits. (7)

The corrected -BPD can be calculated using the formula:

6 Transverse cerebellum diameter

The cerebellum is dumb-bell-shaped and consists of two circular

hemispheres separated centrally by the more hyperechoic triangular shaped

vermis. The section required to measure the transverse cerebellum diameter

(TCD) is the suboccipitobregmatic view, in which the anterior horns of the

lateral ventricles and cavum are visualized at the front of the head together

with the cerebellum at the back. Obtain the lateral ventricle view required

for the BPD then rotate the probe slightly downward, toward the fetal neck.

The posterior horns of the lateral ventricles will disappear from view to be

replaced by the cerebellum. The TCD is measured at 90° to the long axis of

the cerebellum across its widest point, using the ‘outer to outer’ the TCD

measurement (in millimeters) is numerically equivalent to the number of

weeks of gestation of the pregnancy. It is therefore useful in the assessment

of gestational age, especially when there is a discrepancy in gestational age

equivalent between the BPD or HC and the femur. (10)

Figure (2.7) Transvers cerebellum diameter. (8)

2.3.2.2 Bones lengths measurements

1 Femur length

Femur length (FL) is generally the easiest of the stander fetal biometric

images to perfume; the length of the diaphysis of the femur is often used for

gestational age predication. The femur echo can be identified by using the

iliac bone as are reference point and rotating the transducer until the longest

FL is obtained. The calipers are positioned to measure the end-to-end length

of diaphysis excluding any ossified portion of femoral neck, head and distal

or proximal epiphyses, which are visualized only in 3rd trimester. FL is

proposed in the AIUM OB Guidelines as a standard measurement for

determination of gestational age in the 2nd and 3rd trimester because FL

shape independent and usually measurable regardless of fetal posture, it

generally a better parameter than BPD or HC in third trimester. (6, 7)

In any routine obstetric evaluation, the femur is usually the only long bone

measured, but if there is a two week or greater difference between femur

length and all the other biometric parameters, all fetal long bones should be

measured and a targeted examination of the fetal anatomy should be

performed.(8)

Figure (2-8) Fetal femur length measurement. (8)

2 Tibia and fibula length

The tibia and fibula can be measured by first identifying the femur, then

following it down until the two parallel bones can be identified. The tibia

can be identified because the tibial plateau is larger than the fine, tapering

fibula. The tibia is located medial to the fibula. (8)

3 Humeral length

Is sometimes more difficult to measure than femur length. The humerus is

usually found very close to the fetal abdomen, but it can exhibit a wide range

of motion. The “upside” humerus, or the humerus closest to the transducer,

falls in the near-field zone, where detail is not always focused and the

acoustic shadow is less clear. The opposite, or “down side”, humerus may be

obscured because of the overlying fetal spine or fetal ribs. The cartilaginous

humeral head surface is also acoustically shiny and may produce specular

reflections that should not be included in the measurement of the humeral

diaphysis. (8)

4 Radius and Ulna length

The radius and ulna can be recognized by following the humerus down until

two parallel bones are visualized and then rotating the transducer slightly

until the full length of the bones is identified. The forearms are commonly

found near the fetal face. The ulna can be distinguished from the radius

because it penetrates much deeper into the elbow. The ulna is larger and

anatomically medial. (8)

2.3.2.3 Abdominal circumference

The first description of the use of the fetal abdominal circumference (AC) in

predicating fetal weight was in 1975. AC is length of the outer perimeter of

fetal abdomen, measured in true axial section of upper abdomen of fetus at

level of the umbilical vein, left portal vein, and portal sinus confluence;

other features of the AC image include the fetal stomach and aorta. In older

fetuses the adrenal glands and inferior vena cave may also be seen. The AC

is very useful in monitoring normal fetal growth and detecting fetal growth

disturbances, such as intrauterine growth restriction (IUGR) and

macrosomia. It is more useful as a growth parameter than in predicting

gestational age. The AC may be obtained directly from frozen image on the

viewing screen by tracing the outer edge of the fetal abdomen (skin/amniotic

fluid interface) with tracing the calipers or by using linear calipers to obtain

the widest anteroposterior and transvers diameters of the abdomen and using

the formula for the circumference of a circle (same as for HC) to determine

the AC. The two diameter measurements should be right angle or

perpendicular to each other. (7, 8)

D1= is the widest anteroposterior diameter

D2= is the widest transverse diameter

Of the four basic gestational age measurements, AC has the largest reported

variability and is more affected by growth disturbances than the other basic

parameters. Later in gestation, the AC correlates more closely with fetal

weight than with age. (7, 8)

Figure (2-9) Abdominal circumference measurement. (8)

2.3.2.4 Composite dating

Refer to the use of two or more fetal parameters to determine the mean

gestational age. The AIUM OB Guidelines propose at least two parameters

be used to determine gestational age with ultrasound in second and third

trimester. (7)

2.4 Previous studies

Orji MO et al in (2014) were done study to establish baseline data for TCD

at various corresponding gestational ages in Nigerian women, and evaluate

the correlation between these two parameters. Prospectively study done in

Four hundred and fifty healthy singleton pregnant women, referred for

antenatal scans were following informed consent. Main inclusion criterion

was certain last menstrual dates. A SONOACE χ⁶ ultrasound scanner, with a

curvilinear probe and 3.5 MHz transducer, was used to measure the TCD.

Data analysis was done and statistical significance set at p ≤ 0.05, the fetuses

studied ranged from 11.9 mm (at 13 weeks) to 59.3mm (at 41 weeks) with a

mean value 34.2 ± 14.1mm. There was significant correlation between TCD

and menstrual gestational age (r =0.984, p=0.000). TCD has a predictive

accuracy of 96.9% with a standard error of ± 10 days. (11)

Another study done by Nihal AH et al (2015) in 100 normal pregnant

women's in second and third trimester, with accurate LMP, the relationship

of gestation age depend on last menstrual period and trans cerebellar

diameter was analyzed in to five groups, less than 20 weeks, 20-24 weeks,

25-29 weeks, 30-34 weeks and 35-39 weeks, the most frequent group 25-29

weeks (27%) and 35-39 (28%) respectively. Chi-square showed no

significant difference (p=0.9715). Interaction relationship of gestation age

depends on last menstrual period, BPD and TCD was analyzed into five

groups, less than 20 weeks, 20-24 weeks, 25-29 weeks, 30-34 weeks, 35-39

weeks, the most frequent group 25-29 weeks (27%) and 30-34 weeks (28%)

respectively. No significant difference (p= 0.9968), fetal TCD by ultrasound

could be used a predictive biometric parameter of Gain last two trimester of

pregnancy in comparison to other biometric parameter. (4)

Mustafa Z. Mahmoud et al (2013) in study aimed to evaluate whether TCD

in singleton gestation can serve as a reliable of GA in the second and third

trimester, prospective study was carried out with 50 pregnant ladies, and GA

ranging from 15 to 37weeks, with single fetus, TCD measured was used for

each fetus. Correlations between fetal TCD and GA were determined for

whole sample. Mean TCD was 28.6 ±7.5 mm in 15-37 weeks of gestation,

Regression analysis indicate a significant relationship between TCD and GA

correlation coefficient = 0.94 and p<0.000. That means fetal measurement of

TCD by ultrasound could be a predicative biometric parameter of GA in last

two trimesters. (12)

In Anathor study R Negesh et al (2016) in a prospective cross sectional

study consisting of 100 normal singletons gestations in period of 15-40

weeks. The average gestational age of all fetuses was calculated by using

biparietal diameter, head circumference, abdominal circumference and

femoral length, fetal transverse cerebellar was measured. Liner correlation

between transverse cerebellar diameter and gestational age (correlation

coefficient r=0.992, p<0.001), TCD can be used as a reliable parameter in

estimation of gestational age. (5)

Charusmita Agrawal et al (2013) in study was carried out with 100

singletons pregnant women, ultrasound examination for TCD and gestation

age was done between 20-28 weeks and between 30-36 weeks. Mean age of

the women was 24.82 + 3.31 and 85% women were in age group 21-30. The

mean TCD in 20-28 weeks was 24 ± 3.86 and in 30-36 weeks was 39.31 ±

2.51. Median TCD increases from 20.35 mm at 20 weeks to 41.7 mm at 36

weeks of gestation. The correlation coefficient between gestational age and

TCD was 0.971, which indicate high relation with p value <0.0001. The

study showed linear relationship between TCD and gestational age at 20-28

weeks and 30-36 weeks, so TCD is a reliable method of gestational age

determination in early as well as in late pregnancy. (13)

Prabhat Goel et al (2010) in study the TCD was measured to estimation

gestational age in 50 singleton pregnant. The mean TCD was 17.32 mm in

14-20 weeks of gestation, 26.63 mm in 21-30 weeks and 40.73 mm in 31-40

weeks, the correlation coefficient between gestation and TCD was found to

be +0.991, which was statically significant (p<0.0001) and indicate that

TCD is a good marker for estimation of gestation age. (3)

Chapter Three


Chapter Three


3.1 study Design

This was cross sectional descriptive study.

3.2 Study Area

The study was conducted in Shifa AL Aliel Modern Medical Hospital

Omdurman and some private centers.

3.3. Study Duration

The study was conducted during a period of four months; spanning from

August 2016- November 2016.

3.4 Study Population

The date of this study were obtained from 104 Sudanese pregnant ladies

with singleton normal pregnancies and accurate last menstrual period

attending the clinical for routine ultrasound examination and follow up

antenatal care between 14 to 40 weeks of pregnancy.

3.5 Inclusion criteria of the study

All normal singleton pregnant women with accurate LMP from 14-40

weeks.

3.6 Exclusion criteria of the study

3.6.1 Unknown LMP.

3.6.2 Multiple pregnancy.

3.6.3 Pregnancy with medical complication.

3.7 Data collection tools

Verbal consent was firstly obtained from all potential participants. The aims,

benefits of the present study were explained to all participants in details.

Medical, obstetric and gynecological history of all study subjects sample

will be thoroughly reviewed directly from participants themselves and those

with conditions that may –in any way- alter the findings of the current study

were excluded.

3.7.1 Measuring of fetal gestational age

In this study after taking a verbal consent and used AIUM practice

parameter for performance of obstetric ultrasound examination, Scanning

was done in room with dim light, to minimize the reflected artifact of the

screen. The cases were examined in supine position then applying a sonic

coupling agent to abdomen, and begin the evaluation with a simple sweep of

transducer up and down to the abdomen and side-to-side across the abdomen

to get a rough sense of the abdominal contents before focusing on specific

areas of interest. (15)

Biparietal diameter (BPD) measurement was taken from transverse axial

section , from outer edge of skull bone to inner edge of skull bone at level of

thalamus and the cavum septi pellucidi ,inter cranial landmark should

include the flax cerebri ,cavum septi pellucidi ,thalamus and choroid plexus

in atrium of each lateral ventricle.

Transverse cerebellum diameter was measured from the level at which BPD

was obtained by angling transducer to the posterior fossa to include the full

width of cerebellum; the widest transverse diameter of cerebellum was

measured.

Femur length was measured by used iliac bone as reference point then

rotated the transducer until the longest FL is obtained the calipers were

positioned at end to end length of diaphysis excluding any ossified portion.

Figure (1-3) Show electronic calipers place in TCD measurement. (8)

3.7.2 Instrumentation

In this study areal time Mindary DP 20 digital ultrasound system with 2 to

6 MHZ curve liner transducer.

The scan was in international guidelines and protocols and data collected in

the data collection sheet (structured questionaire) that contains study

variables were used for data collection.

3.8 Data Analysis

Data were analyzed using Statistical Package of Social Sciences (SPSS).The

data obtained were analyzed statistically by computing descriptive statistics:

Mean ± SD values and percentages. Paired T-test were obtained for testing

the difference between the formulae results. The difference at value of

P<0.000 will be considered significant.

3.9 Ethical consideration

1- Verbal approval from the head department to conduct the current study

was first obtained.

2- All participants were informed after objective of this study were clarified.

3- Each potential subject participating in current study was thoroughly

informed about, aims, methods, the anticipated benefits of the study and the

discomfort it may entail.

4- All subjects were informed about their right to abstain from participation

in the current study and their option of withdrawing to participation at any

time without reprisal.

5- No information revealing the identity of any individual was included in

the final report or in any other communication prepared in the course of the

research.

Chapter Four

Results

Chapter Four

Results

Table (4.1) Average gestational age per weeks, BPD, FL and TCD.

Table (4.2) measurement per mm BPD, FL and TCD.

Variable N Minimum Maximum Mean Std. Deviation

Measurement of FL per mm 104 24.00 74.00 52.2596 12.74393

Measurement of TCD by

mm

104 16.40 52.00 32.2817 8.64004

Measurement of BPD per

mm

104 36.00 94.00 68.1923 14.32838

Valid N 104

Variable name N Minimum Maximum Mean Std. Deviation

Average GA per weeks 104 16.86 38.00 27.8970 5.32727

BPD per week 104 16.86 38.86 27.9904 5.39662

FL per week 104 16.86 37.57 27.7871 5.27173

TCD per week 104 16.71 37.57 27.2170 5.33565

Valid N 104

Table (4.3) Frequency distribution of Average gestational age group.

AVG age

group

Frequency Percent Valid Percent Cumulative

Percent

14-20 weeks 14 13.5 13.5 13.5

20.1-30weeks 50 48.1 48.1 61.5

30.1- 40 weeks 40 38.5 38.5 100.0

Total 104 100.0 100.0

Table (4.4) minimum, maximum, means and STD of TCD per mm in

(14-20 weeks).

N Minimum Maximum Mean Std. Deviation

measure TCD by

mm

14 16.40 20.00 18.1857 1.12034

Valid N

(listwise)

14


(20week +1d to 30 weeks).

N Minimum Maximu

m

Mean Std. Deviation

measure TCD by

mm

50 17.90 35.50 29.218

0

4.23410

Valid N (listwise) 50


(30 wks +1d to 40 weeks).

N Minimum Maximum Mean Std.

Deviation

measure TCD by

mm

40 35.00 52.00 40.8900 4.29345

Valid N (listwise) 40

Figure (4.1) shows correlation between gestational age by TCD

per weeks and average gestational age per weeks.

Figure (4.2) shows correlation between GA by BPD per weeks and

average gestational age per weeks.

Figure (4.3) shows correlation between GA by FL per weeks and


Figure (4.4) shows correlation between TCD measurement per mm and



average gestational age by TCD per weeks.


gestational age by FL per weeks.


gestational age by BPD per weeks.


measurement of BPD per mm.


measurement of FL per mm.

Figure (4.10) shows correlation between GA by TCD per weeks and

GA by BPD per weeks.

Figure (4.11) shows correlation between GA by TCD per weeks and

Table (4.7) correlation between TCD in mm with GA by BPD, FL, TCD

and with Average GA. Measure TCD

by mm

GA per day

TCD

BPD week FL week TCD week Avera

ge

week

measure

TCD by mm

Pearson Correlation 1 .996** .982** .975** .996** .985**

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

N 104 104 104 104 104 104

GA per day

TCD

Pearson Correlation .996** 1 .986** .978** 1.000** .989**

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

N 104 104 104 104 104 104

BPD week Pearson Correlation .982** .986** 1 .979** .986** .997**

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

N 104 104 104 104 104 104

FL week Pearson Correlation .975** .978** .979** 1 .978** .987**

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

N 104 104 104 104 104 104

TCD week Pearson Correlation .996** 1.000** .986** .978** 1 .989**

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

N 104 104 104 104 104 104

Average GA

by weeks

Pearson Correlation .985** .989** .997** .987** .989** 1

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

N 104 104 104 104 104 104

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

Chapter Five

Discussion, Conclusion

and

Recommendation

Chapter five

Discussion, Conclusion and Recommendation

5.1 Discussion

Determination of gestational age is important in obstetric for management

of pregnancy and evaluated of fetal development. Higher perinatal mortality

has been reported in patients whose expected data of delivery is not known.

An error in gestational age estimation can result in prematurity and

postmaturity. Extremes of fetal growth contribute disproportionately to

overall perinatal and infant morbidity and mortality. Among various clinical

criteria, Last menstrual period preceded by normal cycle, is known to

correlate best with gestational age but is not reliable in a women is not sure

about her LMP.

Other biometric parameters for GA assessment are biparietal diameter,

femur length and head circumference. These parameters have their own

limitation as BPD after 26 weeks becomes more related to growth and also

unreliable in conditions altering the shape of skull i.e. in breech presentation

and oligohydraminons. Similarly femur length is also unreliable in cases of

femur achondroplasia.

Cerebellum lies in posterior cranial fossa, surrounded by the dense petrous

ridge and occipital bone so it can withstand deformation by extrinsic

pressure better than the parietal bone.

In this study frequency distribution of patients according to gestation age

per weeks, BPD, FL and TCD were analyzed and the mean average

gestational age per weeks depend on LMP was (27.89 weeks ± 5.327

weeks), the mean of average gestational age per weeks depend on BPD, FL

and TCD respectively was (27.99 weeks ±5.271 weeks), (27.78 weeks±

5.335 weeks) and (27.21 weeks±5.335 weeks).

The mean and Stander deviation measurements per mm from BDP, FL and

TCD was done, with the mean of BPD is (68.19 mm ± 14.32 mm); the mean

of FL per mm is (52.25 mm ± 12.74 mm), and mean of TCD per mm is

(32.28 mm ± 8.64 mm).

The most frequency distributions of average GA group was 20 wks+1d-30

weeks (48.1%), then 30 wks+1d-40 weeks (38.5%) and the least 14-20

weeks.

At 14-20 weeks the minimum TCD per mm was (16.4 mm), maximum was

(20 mm) and the mean was (18.18 mm), at 20 wks+1d-30 weeks -the most

frequent group- the minimum TCD per mm was (17.9 mm), maximum was

(35.5 mm) and the mean was (29.21 mm), and at 30 wks+1d-40 weeks the

minimum TCD per mm was (35.5 mm), maximum was (52 mm) and the

mean was (40.89 mm). When individual observation of the TCD per mm

related to TCD in weeks, liner relationship was seen. The relationship has

been show in scatter diagram (fig 4-5), with R2 =0.9924 it was significant as

P≤ 0.000.

Results show also a liner relationship between GA per weeks and TCD

measurement in mm. The correlation has been show in scatter diagram

figure (4-4) with R2 =0.9696 and R=0.985 it was significant as P≤ 0.000.

This was agreeing with parbhat Goel; et al (2010), they found that there was

liner relationship between gestation per weeks and TCD per mm. This was

also agreeing with Mustafa Z.et al (2013), they found that there was liner

correlation between fetal TCD mm and GA per weeks (R2 =0.94 and p<

0.001). Also anther study by Nihal AH et al (2015) as P =0.9968 and there

significant relationship between TCD per mm and GA per weeks, also

Nagesh et al (2016), observed that there was liner relationship between TCD

per mm and GA per weeks as R=0.992, and P<0.001.

A liner relationship between TCD per mm and BPD per mm was seen with

R2=0.9485 it was significant at P≤0.000, the correlation between TCD per

mm and BPD per mm has been show in scatter diagram (fig 4-8).

A liner relationship between TCD per mm and FL per mm was seen with R2

=0.9525 it was significant as p≤0.000, the correlation between TCD per mm

and FL per mm has been show in scatter diagram (fig 4-9).

There were liner relationship between TCD per mm GA per weeks, and liner

relationship between TCD per mm and BPD and FL per mm.

5.2 Conclusion

The study found that there was linear relationship between TCD per mm and

fetal gestational age per weeks. In normally developing fetus, the TCD

increases with advancing gestational age. The study found that the mean

TCD per mm in 14-20 weeks was 18.2 ± 1.12 mm, the mean TCD per mm in

20+1- 30 weeks was 29.22 ± 4.23 mm, and the mean TCD per mm in 30+1d

- 40 weeks was 40.89 ± 4.29 mm. The relation between TCD and gestation

age was well correlated. There was a good correlation between the fetal

gestational age and transverse cerebellum diameter so TCD measurement

can use as reliable and accurate parameter to estimate gestational age in

second and third trimester. It is very useful parameter in assigning

gestational age in patient where correct LMP is not known. The study

showed the normal range of cerebral measurements throughout of gestation

these values may allow intrauterine assessment of the development of the

cerebellum as well as the posterior fossa.

5-3 Recommendation

1. The TCD show liner relationship with GA so we recommended using

TCD as alternative parameter to estimate gestational age in second and

third trimester.

2. Cerebellar shape change as gestational age developing good knowledge

of this change help to avoid incorrect measurement.

3. Further studies should be performed with taking large sample volume

size to establish chart for measurement of gestational age by transverse

cerebellum diameter for Sudanese women, and cerebellar grading should

be done.

4. Since the cerebellum it found in posterior fossa and it surrounded by

dense petrous ridge and occipital bone and TCD measurement in both

second and third trimester remained consistently superior in prediction of

GA we recommended that further studies to evaluate whether TCD in

singleton gestations age can serve as reliable predication of GA in fetuses

with abnormal growth.

References

References

1. William PL Grays's Anatomy, 38th edition, Churchill Livingstore,

Edinburgh: London. 1995; P-1027-1028.

2. Richard D Mcllary, Lawrence R Kuhns, Mason Barr Jr. Ultrasonography

of the fetal cerebellum. Radiology 1984; 151:439-442.

3. Prabhat Goel,MukeshSingla et al,J Anat. Soc. India.2010; 59(2):158-161.

4. Nihal AH, Ahmed Abd Elrahim et al, SJAMS.2015; 3(9B): 3219-3223.

5. R Nagesh,Seetha Pramila et al, International Journal of Contemporary

Medical Research.2016;3(4).1029-1031.

6. Carol M.Rumack, Stephanie R.Wilson, J.William Charboneau, Deborah

Leveine. Diagnostic Ultrasound. 4th Edition. Elsevier; Philadelphia:

2011.P -1455, 1457-1458, 1197-1198, 1220-1224.

7. Denis Gratton, Obstetrical Ultrasound, The Burwin Institute of

Diagnostic ultrasound; Manitoba, Canada: 2001. Module Two P-1, 9-10,

13-15, 18, 20, Module Four P 28-29.

8. Sandra L.Hangen-Ansert. Textbook of Diagnostic Ultrasound. 7th edition

; Elsevier; 3251 Revierport lane St. Louis Missouri 63043 : 2012. P-

1146, 1150-1153, 1297.

9. Alexendra Stanisavsky et al. Bipariteal diameter.Radiopaedia.org.

;15.9.2015. Available from URL. http:// radiopaedia-org/article/

biparietal diameter.

10. Trish Chudleigh, Basky Thilaganathan. Obstertric Ultrasound How,Why

and When. 3rd edition. Elsevier; Edinburgh: 2004. P-105.

11. Orji MO, Adeyekum AA. West Afr J Med. 2014; 33(1):7-61.

12. Mustafa Z.Mahamoud, Omer A.mhamoud et al, International Journal of

Life Science and Medical Research.2013;3(3):89-93.

13. R Nagesh,Seetha Pramila et al, International Journal of Contemporary

Medical Research.2016;3(4).1029-1031.

14. Charusmita Agrawal,Kamlesh Kumar Agrawal et al,Int J Repord

Contacept Obstet Gynecol.2015;4(6):2010-2013.

15. Gilani.SA. Guideline and protocols for medical Diagnostic Ultrasound

scanning technique. Maha Publishing Company; Lahore Pakistan: 2004.

P. 101 – 154.

Appendices

National Ribat University

College of Graduate Studies

Data collection sheet

No Clinical dating

BPD

FL TCD Average

GA

LMP EDD GA/W EDD GA/W EDD MM GA/W EDD GA

(Image1) Show average GA 21 wks+1 d, and measurement of transverse

cerebellum diameter = 22mm.

(Image 2) show average GA 31 wks + 6 d, and measurement of transverse

cerebellum diameter = 39.7mm

(Image 3) Show average GA 34 wks + 2 d, and measurement of transverse

cerebellum diameter = 42.8mm.

(Image 4) Show average GA 18 wks, and measurement of transverse


(Image 5) show average GA 30 wks + 1 d, and measurement transverse


(Image 6) show average GA 27 wks + 5 d, and measurement of transverse

cerebellum diameter = 32.3mm

(Image7) Show average GA 24 wks, and measurement of transverse




(Image 9) Show average GA 33 wks +4 d, and measurement of transverse




(Image 11) Show GA 31 wks + 5 d, and measurement of transverse



cerebellum diameter = 24.8 mm.

(Image 15) show average GA 34 wks, and measurement of transverse




(Image 17) Show average GA 25 wks + 5 d, and measurement of Transverse






(Image 24) Show average 26 wks + 3 d, and measurement of transverse





cerebellum diameter =34.5mm.

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