Obstetric Flashcards
After fertilization the ovum turns into what cell, which contains 46 chromosomes
zygote
after a zygote goes through a division process called cleavage and then transitions into a which contains 16-32 cells
morula
on day 18-19 the morula exits the fallopian tubes into the uterine cavity and endometrial fluid penetrates the cell mass and creates what
blastocyst
what is the blastocyst inner cell mass as well as the outer shell of cells
-embryoblast (future embryo)
-trophoblast (future placenta)
what are the two layers of the trophoblast
-syncytiotrophoblast (outer)
-cytotrophoblast (inner) becomes the amnion
Which hormone is produced by the trophoblast
hCG (Human Chorionic Gonadotropin)
What days does the blastocyst attach to the endometrium
day 20-21
this is the anchor point for the blastocyst and begins the development of the primitive placenta
decidual basalis
Refers to the changes that occur in the endometrium in response to the implantation of a fertilized egg. The stromal cells of the endometrium enlarge, forming into decidual cells.
decidua reaction
if pregnancy takes place what two layers will begin to form at the syncytiotrophoblast to serve as the blood vessels to the placenta
chorionic villi to chorionic frondosum
a normal gestational sac is a rounded anechoic structure and seen in ultrasound at approximately what weeks LMP
5 weeks
early sonographic depiction of the GS (gestational sac) with an anechoic endometrial space and further out of the decidua capsularis. This is known as.
the double sac sign is a reliable indicator of a developing pregnancy in the very early stages
-initiation of placental development
-develops alimentary canal
-neuroplate develops into neurotube (future brain)
-fetal lungs beginning to develop but not yet active
Ovarian phase weeks 4-5
-primitive heart begins to beat
-primitive brain consists of : forebrain (prosencephalon), midbrain (mesencephalon), hindbrain (rhombencephalon)
embryonic phase weeks 6-10
-formation of anterior and lateral abdominal walls
-yolk sac fuses with vitelline duct to become umbilical cord
weeks 7-8
-mineralization of skeleton begins
-embryo becomes c-shaped with limb buds
-small bowel herniates at base of umbilical cord (developed outside of baby body before the abdominal walls closes on it) AKA gastroschisis
weeks 8
-functional fetal kidneys appear
-major organ system is established
-embryo demonstrates baby features
week 10
-organ development
-fetal intestinal activity begins
-fetal swallowing
fetal phase weeks 11-12
developed into nanotube brain and spinal cord
neuroplate
The innermost membrane of developing embryo
Amnion
Outermost layer of the developing embryo
chorion
Structure is responsible for production of amniotic fluid
-chorion frondosum
-chorionic and amniotic membrane
-skin, respiratory, and urinary tract
structures involved in reduction of amniotic fluid
-gastrointestinal system
-amniotic - chorionic interface
MSD (mean sac diameter)
(Length + Depth + Height)/3 = MSD
Most accurate to get GA; must be completed within the first 6 weeks
measurement made from top of the head to middle of buttocks
CRL (Crown Rump Length)
To determine the fetal risk for aneuploidy; is the measurement of the fluid that normally collects at the back of the fetus neck during the first trimester between 11-13 weeks; 3-3.5 cm if bigger it means congenital abnormality
NT Measurement (Nuchal Translucency)
Within the gestational sac there is a membrane formed from scarring or adhesions secondary to surgery or infection inside the GS
uterine synechia; doesnt attach to embryo
-normal levels increases doubling every 48 hours
-2000 is the level at which a sac will be seen in most early pregnancies
B-HCG test (Beta Human Chorionic Gonadotropin)
-elevated levels indicate fetal abnormalities
-found in maternal blood and AF
AFP (Alpha-Fetoprotein)
Triple marker screen: all 3 are indicators of certain embryonic/fetal abnormalities
AFP, uE3 (Unconjugated Estriol), HCG
the importance of testing the maternal/paternal blood typing
-determine blood type and Rh factor
-if mismatched mother’s antibodies will attack baby’s RBC’s and lead to miscarriage
fluid in amniotic sac measures degree of fetal lungs
LS ratio ( Lecithin-to-Sphingomyline)
1st trimester can be termed as
trimester of differentiation and developement
2nd/3rd trimester can be termed as
trimester of growth and maturation
placenta grading
Grade
- 0: smooth chorionic plate. Basal layer is free of bright reflective densities.
- 1: placenta exhibits a few scattered hyperechoic calcifications
-2: chorionic plate exhibits, mild or midsize indentations
- 3: Obvious indentations in chorionic plate that extends as far as basal layer
Four types of placenta previa
-Total or complete; the placenta covers the entire internal os
-Partial or incomplete; partially covers the internal os
-Marginal; small edge of the placenta encroaches upon the internal os, but does not cover
-low lying; lower edge lies within 0.5 to 5 cm from internal os
permits growth, prevents adhesions, protects the fetus, and temperature control. Particles flowing consist of skin flakes, hair, urine.
Amniotic fluid
normal AFV (amniotic fluid volume) quantity
Greater than 2 cm in a single pocket or four quadrant measurement (AFI) of 8 to 25 cm
Too much amniotic fluid over 30 cm; the baby is not swallowing properly and looks abnormally tiny
Polyhydraminos
Two little amniotic fluid less than 6 cm; the baby is smooshed within the uterus due to kidney issues
oligohydraminos
measures outer to inner wall of the head; can be used at 10 weeks or to term. It is less accurate in the late third trimester.
BPD (Biparietal Diameter)
Measures from outer to outer wall of the head; can be used from 12 to 40 weeks
HC (Head circumference)
measures the perimeter of the abdomen, including the soft tissues. Taken in the transverse plane at the level of ductus Venosum. Good from 12 to 40 weeks.
AC (abdominal circumference)
Measures the straight shaft of the femur, do not include epiphysis
FL (femur length)
Forehead shape of fetus, used to verify accuracy of the BPD
Cephalic index (cI)
-Dolichocephalic: rolled out dough
- Bradycephalic: wider, protruding forehead
test completed for a second trimester anatomical survey (sonographic); not as reliable for EDD (estimated due date) compared to first trimester calculations
1- R/O ectopic pregnancy, ovaries, myometrium to R/O fibroid or myoma
2- placenta location, R/O previa, cervix length, umbilical cord insertion, Age/grade of placenta
3- Fetus measurements (BPD/HC, AC, FL)
Which markers are used during the BPD measurement
-Cava septum pellucidum; square shaped with white border
-midline falx
-thalamus
what markers are used during the abdominal circumference test?
-Stomach bubble
-umbilical vein; the intrahepatic portion should be visible at the level of the portal sinus
-vertebra; three circular dots and should be in the three or 9 o’clock position
-kidneys; should not be visible
-adrenal glands; Maybe visible next to the vertebra
DCDA (Dichorionic Diamniotic)
two placenta, two sacs (1-3 days)
MCDA (Monochorionic Diamniotic)
one placenta, two sacs (4-8 days)
MCMA (Monochorionic Monoamniotic)
one placenta, one sac (9-12 days)
Formed embryonic disc joined between 13-15 days
conjoined twins
Fetus without the cranial vault (functioning brain)
-anencephaly
fetus lacking closure of the vertebral column with extrusion of spinal cord and meninges
spina bifida
sac of lymph fluid at the fetal head and neck region
cystic hygroma
fetus with an absence of the kidneys
renal agenesis
Fetus with intestines are outside the abdomen and surrounded by a membrane; very dangerous
omphalocele
fetus with intestines are outside the abdomen without a surrounding membrane and free floating; surgically repairable
gastroschisis
fetal blood flow beginning from placenta
placenta > umbilical vein > Ductus venosus > IVC > Rt. Atrium > Foramen Ovale > Lt. Atrium > pulmonary trunk > lungs
» pulmonary trunk»_space; foramen ovale»_space; AO
TGC
Time Gain Compensation
