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Multiple pregnancy with two chorionic sacs


Multiple pregnancy with one chorionic sac


Formed at 23 days when the primary yolk sac is pinched off by the extraembryonic coelom

secondary yolk sac

Length of time calculated from the first day of the last normal menstrual period to the point at which the pregnancy is being assessed

menstrual age

multiple pregnancy with one amniotic sac


Conceptus resulting from union of male and female gametes


Age calculated from when conception occurs

embryologic age

Multiple pregnancy with two amniotic sacs


First site of formation of red blood cells that will nourish the embryo

primary yolk sac

High-frequency transducer that is inserted into the vaginal canal to obtain better definition of first-trimester pregnancy.

transvaginal transducer

Uterine decidua on the surface of the implantation site

decidua capsularis

Surrounds the amniotic cavity and contains the yolk sac

chorionic cavity

Hormone secreted by the trophoblastic cells of the blastocyst; laboratory test indicates pregnancy when values are elevated

human chorionic gonadotropin

Time between 4 and 10 weeks' gestation

embryonic period

The umbilical duct connecting the yolk sac with the embryo

yolk stalk

Most accurate measurement of the embryo in the first trimester

crown-rump length

Production and development of blood cells


Mean sac diameter


Interface between the decidua capsularis and the echogenic, highly vascular endometrium

double decidual sac sign

Cavity in which the fetus exists; forms early in gestation; fills with amniotic fluid to protect the fetus

amniotic cavity

Intrauterine pregnancy


Uterine decidual surface on the maternal side of the placenta

decidua basalis

Invasive diagnostic genetic testing that involves sampling zygotic cells from developing placental tissue

chorionic villi sampling

Clinicians and sonographers use ________ to date the pregnancy, with the first day of the last menstrual period as the beginning of gestation.


In the first 9 menstrual weeks, the conceptus is called an ________


For the first time after the first 9 weeks, the embryo is called a ________.


The gestational age (age known as postmenstrual age) is calculated by adding ____ weeks to conceptual age.


The fertilized ovum, which now should be referred to as a ________, undergoes rapid cellular division to form the 16-cell morula.


The blastocyst typically enters the uterus 4-5 days after fertilization, with implantation occurring _______ days after ovulation.


Although the organ function remains as minimal, the ________ system is the first organ to develop rapidly, with the first heartbeats noted between 5.5 and 6.5 weeks


Gestational sac size and hCG levels increase ________ until 8 menstrual weeks


After 8 weeks, hCG levels ________ and subsequently decline while the gestational sac continues to grow.


A normal gestational sac can be consistently demonstrated when the hCG level reanges between __________mIU/mL.


The sonographer must be aware that when the hCG level is elevated and the gestational sac is not seen within the uterus, an ________ pregnancy should be considered.


The interface between the decidua capsularis and the echogenic, highly vascularized endometrium forms the _____________________

double decidual sac

The gestational sac size grows at a predictable rate of ____ mm per day in early pregnancy


The first intragestational sac anatomy seen is the sonographic ________ sac, which is routinely visualized between 5 and 5.5 weeks' gestation.


The limb buds are embryologically recognized during the ______ week of gestation.


The spine is also developing during the embryonic period, particularly in the ________ weeks of gestation.


The embryonic face undergoes significant evolution starting in the 5th week of gestation, with palate fusion beginning around the_______ week of gestation


At approximately 10 weeks' gestation, the midgut loop continues to grow and rotate before it descends into the fetal abdomen at about the _____ week


The cystic rhomboid fossa can sonographically be imaged routinely from the _______ week of gestation.


It is important to note that the________ventricles completely fill the cerebral vault at this time in gestation


Sonographically, the gestational sac size or mean sac diameter (MSD) is determine by calcalation the average sum of the________,________, and _______ of the gestational sac.

length, width, height

1. zygote
2. fertilization
3. ovum
4. developing follicle
5. implantation
6. blastocyst
7. morula

Label the diagram of normal conception

1. amnion
2. connecting stalk
3. emrbyonic disc
4. yolk sac
5. chorion
6. chorionic cavity
7. amniotic sac
8. umbilical card
9. yolk sac
10. amnion
11. connecting stalk
12. yolk sac
13. chorionic cavity
14. smooth chorion
15. amnion
16. amniotic sac
17. umbilical cord
18. yolk sac remnant

label the development of amnion, yolk sac, and embryo

Thickened decidua
gestational sac(chorionic cavity)
yolk sac

Identify the sonographic findings in this 5-week intrauterine gestation

decidua capsularis

Identify the structure that the arrows are pointing to in this 6-week gestation

curved arrow: amniotic membrane
straight arrows: umbilical cord

In this 8-week gestation, name the structure that the curved arrow is pointing to. Name the structure that the straight arrows are pointing to.

Crown-rump length

What important fetal measurement does this image demonstrate?

embryonic cranium

Identify what the letter "C" represents


Identify the disklike structure adjacent to the yolk sac.


Name the type of multiple gestation you would predict from this image.


Name the type of multiple gestations demonstrated by this sonogram.

Failure to visualize the yolk sac, with a minimum of _____ mm MSD, using transvaginal sonography, should provoke suspicion of abnormal pregnancy.


Transabdominal studies have shown that the yolk sac should be seen within mean sac diameters of _______ mm and should always be visualized with a mean sac diameter of 20 mm.


The growth rate of the yolk sac has been reported to be approximately ______ mm per millimeter of growth of the MSD when the MSD is less that 15 mm.


The early embryo is not identified with transvaginal sonography until heart motion is detected and the crown-rump length measures approximately _____ mm.


The embryonic period is the time between _____ and 10 weeks' gestation.


The primitive neural tube closes by _____ weeks' gestation.


At _______ weeks, three primary vesicles are seen within the fetal brain: the prosencephalon, the mesencephalon, and the rhomencephalon.


During development, the midgut loop of the bowel continues to grow and rotate before it descends into the fetal abdomen at about the_____ week.


Using transvaginal sonography, multiple gestations can readily be diagnosed at very early stages, between ________ weeks

5.5 & 6.5

Sonographically, dichorionic and diamniotic twins appear as _____ separate gestational sacs with individual trophoblastic tissue, which allows the appearance of a thick dividing membrane.


Monochorionic-diamniotic twins appear to be contained within _______ chorionic sac; _____ amnion(s); ______ yolk sac(s), and two embryos are identified.

one, two, two, two

The monozygotic, monoamniotic-monodichorionic twin gestation shows _____ gestational sac with _____ amniotic membrane, which may contain one or two yolk sacs and two-embryos within the simgle amniotic membrane.

one, one

Measurement that includes both fetal orbits at the same time to predict gestational age

binocular disease

Used in the first trimester to estimate appropriate gestational age with menstrual dates

gestational sac diameter

Method whereby the fetus is categorized into small, average, or large growth percentile

growth-adjusted sonar age

Fetal transverse cranial diameter at the level of the thalamus and cavum septum pelluciidum

biparietal diameter

Most accurate measurement for determining gestational age; made in the first trimester

crown-rump length

Used to determine the start date for human pregnancies

last menstrual period

Measurement at the level of the stomach, left portal vein, and left umbilical sign

abdominal circumference

Heart rate before the 9th week of gestation

eembryonic heart rate

Measurement from the humeral head to the distal end of the humerus

umeral length

Size and proportionality of the fetal parameter expressed as age

age range analysis

Normal fetus that measures smaller than dates

small for gestational age

Average age of multiple fetal parameter's age

average age

Measurement of the femoral diaphysis

femoral length

Flattening of the vertex of the skull


Condition in which the orbits are spaced far apart


Refers to the shape of the cerebellum when a spinal defect is present

banana sign

Failure of the vertebrae to close

spina bifida

Absence of one or both eyes


Fetal head is relatively narrow in the transverse plane and is elongated in the anteroposterior plane


Condition of having a relatively high cranial vault with a high or peaked appearance


Abnormally small eyes


Fetal head is relatively wide in the transverse diameter and shortened in the anteroposterior plane


Occurs with spina bifida; frontal loves collapse inward

lemon sign

Condition in which fetus is not growing as fast as normal; usually considered malnourished or abnormal

intrauterine growth restriction (IUGR)

Sonographically, the earliest sign of intrauterine pregnancy is the _______, which appears an echogenic, thickening filling of the fundal region of the endometrial cavity occurring at approximately 3-4 weeks' gestation.


At 5 weeks, the average of the three perpendicular internal diameters of the gestational sac, calculateed as the mean of the _______ diameter, the ________ diameter, and the _______ diameter, can provide an adequuate estimation of menstrual age.

anteroposterior, transverse, longitudinal

The sac grows rapidly in the first ____ weeks, with an average increase of 1 mm per day.


when the gestational sac exceeds _______ mm in mean internal diapeter, a yolk sac should be seen.


Normal yolk sac size should be less than _____ mm; greater than _____ mm has been associated with poor pregnancy outcome

6, 8

When the mean gestational sac diameter exceeds ____ mm, an embryo with definite cardiac activity should be well visualized with transvaginal scanning.


The embryonic echoes can be identified as early as 38-39 days menstrual age, and the CRL is usually ______ mm at this age.


The most accurate sonographic technique for establishing gestational age in the first trimester is

crown-rump length

In general, the CRL should increase at a rate of _____ mm per day


Absence of an embryo by 7-8 weeks' gestation is consistent with an embryonic demise or an _______ pregnancy


If a nomogram is not readily available to identify gestational age, a convenient formula is gestational age is weeks equals _______.

CRL in cm + 6

In the second trimester, the gestational age parameters extend to ______ diameter, ______circumference, _______ circumference, and ______ length.

biparietal, head, abdominal, femur

The reproducibility of the BPD is +/- ______ mm (+/- 2 standard deviations.


Growth of the fetal skull slows from ____ mm per week in the second trimester to _____ mm per week in the third trimester.

3. 1.8

The fetal head should be imaged in a transverse ________ 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 ________ and ________.

thalamus, cavum septi pellucidi

Intracranial landmarks should include the ________ anteriorly and posteriorly, the ________ anteriorly in the midline, and the ________ in the atrium of each lateral ventricle.

falx, cavum septi pellucidi, choroid plexus

The head shape should be ________, not round, because this can lead to overestimation of gestational age, just as a flattened or compressed head can lead to underestimation of gestational age


The calipers should be placed from the ________ edge of the parietal bone to the ________ edge of the opposite parietal bone, or "outer edge to inner edge."

leading, leading

The proper coronal view should be ________ to the standard transverse HC view passing through the thalamus.


One can ________ gestational age from a dolichocephalic head or ________ with brachycephaly.

underestimate, overestimate

The AC is very useful in monitoring normal fetal growth and detecting fetal growth disturbances, such as IUGR, and macrosomia; however, it is more useful as a ________ than in predicting gestational age.

growth parameter

The fetal abdomen should be measured in a transverse plane at the level of the ________ where the ________ vein branches into the left portal sinus.

liver, umbilical

The abdomen should be more ________ than oval because an oval shape indicates an oblique cut resulting in a false estimation of size.


The ________ length is an especially useful parameter that can be used to date a pregnancy when a fetal head cannot be measured because of position, or when there is a fetal head anomaly.


Often an echo from the near side of the cartilaginous distal femoral condyles will be seen, call the "________"; this should not be included in the measure of the diaphysis.

distal femoral point

The tibia and fibula can be measured by first identifying the ________, then following it down until the two parallel bones can be identified


Humerus length is sometimes more difficult to measure than the femur length because the humerus usually is found very close to the fetal ________ but can exhibit a wide range of motion.


The ulna can be distinguished from the radius because it penetrates much more deeply into the ________.


yolk sac, 4 weeks gestational age

Identify the small structure within the gestational sac and estimate the gestational age


what is being measured in this image?

sp=spine, st=stomach, abdominal circumference

Identify the labeled structures in this image
Which measurement is being made at this level?

distal femoral point, femur

Name the structure the arrow is pointing to.
name the structure being measured

A fertilized ovum is called a ________


The most accurate aging measurement is taken _______ in pregnancy.


Follicle that releases mature ovum hemorrhages and collapses to for the corpus luteum and secretes ________ and _________

progesterone, estrogen

The blostocyst contains trophoblastic cells and "inner mass". This later forms the ________


Blastocyst typically enters uterus _______ days after fertilization


During implantation, protoelytic enzymes produced by trophoblasts "eat into" decidual tissue. This creates spaces for _____________.

cell proliferation

At approzimately 23 days menstrual age, primary yolk sac is pinched off, forming _____________, which is what is seen sonographically.

secondary yolk sac

The cardiovascular system undergoes rapid development, with initial heartbeat occurring between __________ weeks.


The last two weeks of the first trimester (weeks _______) constitute the beginning of the fetal period.

11 & 12

HCG ________ every 3.5 days in a normal pregnancy


HCG levels ______ prior to loss of pregnancy


trisomy 21


The decidua basalis is closest to the ________, and the decidua capsularis is closest to the ________.

mom, embryo

Typically, fundal location is noted within the endometrium but closest to the _______.


The gestational sac should appear round or oval. If elongated or angled, this is __________



Mean Sac Diameter- average size of gestational sac

The fetus appears _________ sonographically.


A-yolk sac
B-amniotic sac
C- gestational sac

what are the structures labelled A, B, & C.

The MOST ACCURATE dating measurement is ______

crown-rump length

Normal diameter of yolk sac should not exceed ____ mm


Typically, the yolk sac is reabsorbed and no longer seen sonographically by _____ weeks


CRL should measure ______ mm at 5.5 to 6 weeks


The fetus resides in the __________ cavity.


Amnion and chorion membranes will be seen at _____ weeks


Fusion of membranes, known as _________, occurs at approximately ___________ weeks.

chorioamniotic fusion, 14-15

Time between 4 & 10 weeks of gestation often considered __________ period.


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