Embryology and 1st trimester Anatomy Flashcards
ultrasound reports fetal age from ___
menstrual dates
when does conception occur
2 weeks after last menstruation
the exact date of conception + 2 weeks =_____
gestational age
___: sperm or ovum
gamete
___: formed by the union of sperm and ovum, single cell
zygote
___: cell division occurs and the single cell forms a cluster
cleavage
___: cluster of cells formed by zygote division
morula
the morello becomes what when it enters the uterine cavity
blastocyst
___: well organized cluster of cells surrounded by trophoblastic cells
blastocyst
___: produce progesterone and hCG, involved with implantation, develop into chorionic villi then into placenta
trophoblastic cells
___: tissue that envelops the blastocyst after implantation
decidua capsularis
what portion of the endometrial layer becomes the maternal placenta
decidua basalis
the blastocyst attaches to which endometrial layer
decidua basalis
the amnion and chorion should fuse completely by what week
16
what are the 3 germ layers
- endoderm
- mesoderm
- ectoderm
the endoderm forms what
respiratory system and GI tract
the mesoderm forms what
circulatory and MSK systems
the ectoderm forms what
Brian, CNS and skin
at 5 weeks the CRL should be between _____
2-4mm
at 6 weeks the CRL should be between ____
4-9mm
at 7-8 weeks the CRL should be between ____
6-16mm
at 9-10 weeks the CRL should be between ____
23-31mm
at 11 weeks the CRL should be between ____
41mm
at 12 weeks the CRL should be between ____
53-67mm
what is the structure that connects the yolk sac to the fetal pole
vitelline duct
what are the functions of the yolk sac
- performs hematopoiesis
- delivers nutrients
- produce AFP early in pregnancy
the yolk sac can usually be seen with a TV approach at __ weeks
5
the yolk sac must be see with a mean sac diameter of ____(TA & TV)
- TA 20mm
- TV 8mm
what is a normal yolk sac diameter
less than 5.6mm
what is seen with the double bleb sign
amnion and chorion
when can you usually see the double bleb sign
5.5 weeks, 2mm CRL
the yolk sac disappears by ___ weeks
12
___: yolk sac persists as a diverticulum in the ileum portion of the bowel
mocked diverticulum
the gestational sac should grow appx __ per day
1mm
how do you calculate MSD
length + width + depth/3
how do you calculate gestational age based on MSD
MSD + 30
a mean sac diameter of ___ you should always visualize a fetal pole (TA & TV)
- TA >25mm
- TV >16mm
the embryo usually grows ___ per day
1mm
how to calculate gestational age in days based on CRL
CRL + 42
how do you calculate gestational age in weeks based on CRL
CRL + 6
what is the most accurate method of dating
CRL
dating is most accurate within the 1st trimester within ___ days
5 days
3rd trimester dating is accurate within ___ days
21 days
how do you calculate naegele rule
EDD= LMP + 7days +9months
at 5 weeks what should you see on the ultrasound
- double decimal sac sign at 5.5-6 weeks
- double bleb sign
- fetal pole
- tiny CRL see with TV
what is the first sign of intrauterine pregnancy seen on ultrasound
decimal reaction
an embryo with a CRL of ___ should always demonstrate cardiac activity
7mm
at 6 weeks what is a normal heart rate
100-115bpm
what are the 3 parts of the brain that benign to form at 6 weeks
- prosencephalon
- mesencephalon
- rhombencephalon
prosencephalon becomes what parts of the brain
- forebrain
- becomes lateral ventricles
- cerebrum
- thalamus
the mesencephalon becomes what parts of the brain
- mid brain
- aqueduct of sylvius
the rhombencephalon becomes what parts of the brain
- hindbrain
- pons
- medulla
- cerebellum
- 4th ventricle
the rhombencephalon can be visualized as early as ___ weeks
7
what can you see at 7-8 weeks
- rhombencephalon
- limb buds
- fetal thorax/abdomen grows
- herniation of midgut into base of cord
what is the normal heart rate at 9-10 weeks
145bpm
when is organogenesis complete
8 weeks conception or 10 weeks gestational
what can be seen on the ultrasound at 11 weeks
- cranium and cerebellum
- extremities begin to take shape
- bowel should return to abdominal cavity
when is the nuchal translucency measured
11-14 weeks
when is the herniation of the midgut considered abnormal
after 12 weeks
fetal biometry should be used for dating after ____
12 weeks
what are the basic biometry measurements
- BPD
- HC
- AC
what brain structure divides the brain into two equal halves
falx cerebri
what is located on each side of the fallx
choroid plexus
a compressed or absent 4th ventricle has been associated with what
spina bifida
enlargement of the 4th ventricle can be associated with what
dandy walker syndrome
the heart should be at a __ degree angle in the chest
45
a normal ductus venous waveform is ___
biphasic with positive or antegrade A wave
an abnormal ductus venous waveform demonstrates _____
negative or reversed A waveform
what is dopplered to asses the uteroplacental impedance and risk of preeclampsia
uterine arteries
what kind of waveform do the uterine arteries have in the first trimester
average velocity with mild diastolic flow
what kind of waveform do the uterine arteries have in the 3rd trimester
resistance decreases diastolic flow increased and diastolic notch disappears
