Mod 5 Flashcards
Pregnancy is dated by
Weeks from first day of the last menstrual period or LMP
Pregnancy
40 completed weeks gestation
280 days
3 trimesters
1st trimester
From 0-13 weeks +6 days LMP Confirms: pregnancy Pregnancy location Size of embryo agrees with LMP dating Number of embryos Viability- fetal heart beat with M-mode
Embryo
Conceptus is called this from conception up to 10 weeks LMP
Fetus
After 10 weeks LMP embryo is renamed to this
Sonography uses this date
LMP
Embryologist use this date
Conception date
What do Sonographers measure when determining due date
Crown Rump Length - CRL
Ovulation
Occurs at day 14 in the ideal cycle
LH must surge for it to occur
Ovum is ejected from follicle, propelled towards Fallopian tube
Lives for 12-24 hours
Sperm
200-500 million sperm deposited near cervix 300-500 reach ovum 100 million/ml is the normal count 20 million or less is considered sterile Survives usually for 24hrs - can survive up to 72hrs
Fertilization
Sperm passes through zona pellucida
Sperm head enlarges to become male pronucleus
Ovum completes its second meiotic division to become female pronucleus
Both pronucleo fuse and chromosomes intermingle
Zygote
Union of the sperm and ovum
Also called conceptus
Morula
Cluster of cells
Remains the same size but cells become smaller and smaller with each division
12-16 blastomeres
Blastocyst
Secretions cross the zona pellucida entering the morula forming a fluid cavity
Enters the uterus 6-7 days after fertilization
How long does the ovum travel and where does it eventually get fertilized
Travels about 24-36 hrs to a Pilar portion of Fallopian tube
Implantation occurs
Complete by 11-12 days post ovulation or 9-12 days post fertilization
Suppose to implant on the posterior portion of the uterus on the endometrium fundus
Celvage
Rapid cell decision without a change in the size of original zygote
Blastomeres
Two daughter cells
What are the two parts that the zygote separates into after fluid goes into zygote
Trophoblasts
Embryoblasts
Trophoblast
Outer cell to become placenta and chorion
Chorion
Responsible for fetal tissue
Embryoblast
Inner cell mass forms:
Embryo
Yolk sac
Amnion
What happens when the zona pellucida disappears
Blastocyst implants in the uterus
After implantation
Blastocyst is imbedded in endometrial epithelium
Trophoblasts differentiates into syncytiotrophoblast and cytotrophoblast
Syncytiotrophoblast
Produces hCG
Erodes the endometrial stromatolites and blastocyst sinks into endometrium
Lacunae
Eroded space of endometrium
Become the intervillous spaces of the placenta
Cytotrophoblast
Produces fingerlike projections that extend into the forming lacunae network
Primary chorionic villi
Fingerlike projections of the cytotrophoblast
Two types are:
Chorion frondosum
Smooth chorion/ chorion laeve
Chorion frondosum
Villi directly at the implantation site
Early placenta
Smooth Chorion/ chorion laeve
All the remaining villi around the gestational sac
Decidua cells in endometrium increase in size and content for implantation due to which hormone
Progesterone
What is the cause and the result of the endometrium undergoing a decidua reaction
Ectopic pregnancy
Result is the formation of a pseudo sac
What kind of reaction can occur in a bicoruate uterus
Decidua reaction
Gives the appearance that this is twins as the non pregnant horn response to the increase in hCG
Decidua basalis
Part of the decidua underlying the conceptus
Eventually becomes the maternal side of the placenta
Thickens layer where implantation occurs
Decidua capsularis
Part that covers the gestational sac
Decidua parietalis
All remaining decidua
Double decidual sign
Sonographic descriptor
Opposed layers of the decidua parietalis and capsularis can be identified on early u/s
This should be always be tried to rule out pseudo sacs
Prior to fusion of decidua Vera and capsularis what exists and what happens to it during implantation
Potential space between the two layers
Blood can collect in this space if their is bleeding during implantation
Amniotic cavity
Formed by the small spaces that occur between the inner cell mass and the trophoblast
Occurs by day 9
Blastocyst cavity is renamed to what when the amniotic cavity is visualized and can you see it on ultrasound
No viable on ultrasound
Now called the primitive yolk sac
Double bleb sign
Represent the early amnion and yolk sac
Only seen on EV at around 5 1/2 weeks
Embyro consists of what two layers
Epibalst
Hypoblast
Epiblast
Gives rise to nearly all the cells in the embryo
Also forms the amniotic membrane which houses the amniotic fluid
Hypoblast
Contributes to the formation of the primitive ectoderm
Bilaminar disc
Embryonic disc
Occurs around 4 weeks LMP
What the inner cell mass becomes
What is happening to the inner cell mass when implantation is occurring
It is changing
Trilaminar disc
At 5 weeks LMP
When gastrulation occurs
Gastrulation
Formation of the three layers
Endoderm
Ectoderm
Mesoderm
Endoderm
1st layer to differentiate
Inner layer
Linings of GI and respiratory tract
Ectoderm
2nd layer to differentiate
Outer layer
Forms CNS
Surface ectoderm ex: hair, skin, teeth and nails
Mesoderm
3rd layer to differentiate
Middle layer
Generally forms muscle and bone
Neurulation
Begins at 3 weeks after conception, 5 weeks LMP
Formation of neural plate, neural folds and neural tube
Neural tube
Closes around day 40 LMP
Starts closing in the middle than progresses to the caudal and cephalic ends
Visualizing the embryo on ultrasound
Decidua basalis amd chorion frondosum appear as thickened area along gestational sac
Embryonic pole
Develops in close proximity to chorion frondosum
Secondary yolk sac
Seen on ultrasound from 5 weeks to 10-12 weeks LMP
Occurs when the head and tail of the embryo fold in and incorporate part of the primitive yolk sac
Yolk sac
Provides nutrients prior to circulation Hematopoiesis starts here Forms vessels from allantois Formation of digestive tract occurs here Development of sex glands occur here
Allantois
Diverticulum of the yolk sac
Forms umbilical vessels
Involved in the formation of urinary bladder
Gestational sac grows how much a day
1.1mm
How much does the embryo grow everyday for the first 8 weeks
1-2mm
What is the upper limit of normal for the yolk sac before 10 weeks
6mm
Gestational sac sizes
Mean age- mean sac diameter
6weeks- 1.5cm
7weeks- 2cm
8weeks- 3cm
Qualitative pregnancy test
By urine Takes 2 mins @ home Can detect at 4weeks LMP Must meet threshold to get a positive Negative does not exclude pregnancy -either too early or diluted urine sample
Quantitative pregnancy test
By blood Tests the beta sub unit of HCG Takes 8hrs and is very sensitive Negative by this method excludes pregnancy Will show positive 23 days LMP Plateau at 8 weeks
EV scanning gestation sac sizes
4 weeks- 2-3mm
5 weeks- 5-6mm, yolk sac*2-3mm
6 weeks- CRL 3-4mm, FH seen
7 weeks- CRL 12-14mm
What are the three different units for beta hCG
FIRP
SIS
TIS
FIRP
First international reference preparation
SIS
Second international standard
Values are 1/2 FIRP
Oldest method
TIS
Third international standard
Values are the same as the FIRP
What should be considered if the the hCG is at or greater than the discriminatory zone
Ectopic pregnancy if no IUP is visualized
What is the discrimatory zone for hCG
500-1000 mIU/ml IS EV
1000-2000 mIU/ml IRP EV
If the CRL of the embryo is 5mm or greater by EV what should be detected
Fetal heart motion
What happens to beta hCG levels in a normal IUP until 8 weeks gestation
They should double every 48 hrs
High beta hCG indicates
Multiple fetuses Hydatigiform moles Choriocarinoma Tetatomas Gonadotropin producing tumors
Low beta hCG indicates
Ectopic
Missed abortion, fetal demise
Inaccurate dates
Pseudocyesis
A condition where a women feels pregnant
Symptoms of
: nausea, bloating, full feeling in pelvis
Pregnancy test is negative, ultrasound is normal non gravid uterus, no IUP detetected in endometrium
These symptoms can be created psychologically
Early OB protocol
Sag midline uterus
Trx vag, Cx, fundus
Mean sac diameter if no embryo is identified
If embyro is seen measure CRL 3 times
Document yolk sac if seen
M-mode heart rate if motion seen
Document maternal ovaries
Document hematoma near gestational sac if identified
Document free fluid in two planes if seen
If at 12-14 week do CRL and BPD
EV scanning all pregnancies under 7 weeks gestation
Haploid
A single set of unpaired chromosomes (23)
A cell with 46 chromosomes divides into 2 new cells, each with 23 each with 23 chromosomes by meiosis
Diploid
Paired chromosomes
Organism with 46 chromosomes (23 pairs)
Triploid
3 complete chromosomes sets
69 chromosomes
Trisomy
Condition where there is one extra chromosome present in each cell additional to the normal diploid
Trisomy 21
An extra chromosome on chromosome 21
Results in Down syndrome
What is the karyotype now for Down syndrome
47 xx or xy
Karyotype
How chromosomes are expressed in a diagram
Chromosome set of an individual
Described in terms of both the number and the structure of the chromosomes
Mitosis
Process of nuclear division where cellular material is equally divided between both daughter cells
All cells except gamete cells
Gamete cells
Sex cells
Meiosis
Process that reduces the number of chromosomes in gametes to half
Chromosomes
Threadlike nucleoprotein structure within the nucleus of a cell that contains DNA
DNA
Double stranded nucleus acid that is a constituent of chromosomes
Contains hereditary information coded in specific sequences
Gene
Hereditary unit that carries hereditary traits
For self reproducing
Arrangement of DNA in a chromosome
Karyotype
chromosome set of an individual
discribed in terms of both the number and the stucture
represntation of chromosomes set in a diagram
endovaginal scan when necessary when no what is seen
embryo
embryonic heart beat
why is ultrasound used for obsetrical cases
determines viabilty, dating and number of embryos
why is dating important
certain testing in pregancy is performed at specific times in a pregnancy so that certain milestones of the pregancy are accuratley documented for that gestational age
inccurate dates can be caused by what factors
longer or shorter menstrual cycles
what can inaccuate dates lead to
false positive or negative values
1st trimester screen involves what
nuchal translucency
maternal bood work
what is the only definitve test for a 1st trimemster abnormal screen
amniocentesis
in the 1st trimester screen anything over what value is concidered in the risk assesment range
3mL
what does a nuchal translucency sca asses for
chromosomal abnormalities heart abnormalities lung abnormalities skeletal abnormalities congential infections blood disorders metabolic disorders
why is the 18 week scan the most important
assess all the structures of the fetus
can the 18 week scan be pushed back and if so till when and why
yes till 20 weeks enables the heart to be better visualized
18 week detailed scan involves the measurement of what structures
head spine fetal abdomen fetal chest femur length humerus length ankle veiw open hands placenta umbilical cord maternal structures
what are the measurements and structures of the head that are veiwed in a 18 week detailed screen
BPD HC cavum septum pellucidum cerebeller diameter ventricular diameter nuchal fold cisterna magna orbits nasal bone nose/lips profile
what are the measurements and structures of the fetal abdomen that are veiwed in a 18 week detailed screen
AC stomach kidneys bowel diaphragm bladder
what are the measurements and structures of the fetal chest that are veiwed in a 18 week detailed screen
lungs
heart
what are the measurements and structures of the fetal heart that are veiwed in a 18 week detailed screen
4 chamber LT outflow RT outflow 3 vessel view m-mode for heart rate
what are the measurements and structures of the placenta that are veiwed in a 18 week detailed screen
location
thickness
what are the measurements and structures of the maternal structures that are veiwed in a 18 week detailed screen
cervix
uterus
in a 3rd trimester screen are the anatomy images reassesed if they are normal
no
after 12-16 weeks what is the amniotic fluid comprised of
fetal urine
a 3rd trimester screen is monitoring what
fetal well being- how well the placenta is working and if the fetus is safe in utero
what is assesed in a 3rd trimester screen
biometry for growth of fetus: BDP, HC, AC, FL
fetal heart rate- m-mode
biophysical profile: fetal well being and placental function
placenta: growth and grade
fetal well being encompasses what
fetal movement
fetal tone
amniotic fluid
fetal breathing movements
doppler is needed in 3rd trimester screen if
fetal growth is lagging
amniotic fluid is low
maternal reasons
what are the maternal reasons for doppler to be used in the 3rd trimester screen
high blood pressure
gestational diabetes
what are vessels samples that are taken in a 3rd trimester screen
umbilical artery
middle cerebral artery of fetus
ductus venosus
what is the maternal blood work taken at the 1st trimeseter screen (+ Nuchal)
PAPPA
hCG
what does the hCG level blood test assist with during a 1st trimester screen
nuchal translucency results to validate a problem
what is the maternal blood work taken at 16 weeks gestation
triple screen
quad screen
what is then maternal blood work taken at 24-28 weeks gestation
glucose tolerance screen
what is the glucose tolerance screen testing for
gestational diabetes
does gestational go away and if so when
yes but only when the placenta goes away
what is the time frame that gestational diabetes can impair a mother for
3-5 years
what can gestational dibetes develop into
type 2 diabetes
what does a routine obsetrical doctor visit entail
mom’s: weight, blood pressure and urine
uterine fundal height measurement
postion of the baby by palpation
fetal heart beat rate recorded with doppler
how often does a pregant patient have a routine doctors visit
monthly at the beginning of the pregnancy
every 2 weeks if normal until around 36 weeks
weekly if normal till term
post dates require what
ultrasounds to cheack fetal well being and growth
