OB Flashcards
Parity?
of live births a woman has had
Gravidity?
of times a woman has been pregnant, including current pregnancy
EDD
Estimated date of delivery
EDC?
Estimated date of confinement
Another term for delivery date
Miscarriage?
First trimester pregnancy loss, considered an abortion
When is a threatened abortion suspected?
First trimester bleeding
What’s a spontaneous abortion? When does it usually occur?
Pregnancy loss caused by natural or unanticipated events
Around 8 weeks gestation
What’s recurrent spontaneous absorption?
2 consecutive spontaneous abortions or 3 total
Aka habitual abortion
What’s gestational age based off of? What’s another name for it?
Date of last menstrual period (LMP), sonogram dating methods are based on this
Aka menstrual age (MA)
What does GA equal?
Embryologic (conceptual) age + 2 weeks
What’s Embryologic age? What’s another name for it?
Based of time of conception (embryology references use this age)
Aka conceptual age
How do you get gestational age from embryological age?
Add 2 weeks to embryological age
Which age do we use in clinical practice?
Gestational age
What does serum pregnancy test?
Beta subunits of hCG (human chorionic gonadotropin)
Urine pregnancy tests are qualitative -detect the presence of hCG
What produces hCG?
Trophoblast if cells that make up the placenta and burrow into the endometrium
What are the 2 quantitative lab tests to detect the amount of b-hCG in maternal blood?
How are they related?
- Second international standard (2nd IS): 1/2 the value of IRP
- International reference preparation (IRP): twice the value of 2nd IS
What does the discriminary zone of the 2nd IS and IRPean?
Threshold amount oh hCG at which there should be sonographic evidence
What’s the discriminatory zone for 2nd IS?
500-1200 miu/ml for endovaginal imagining
What’s the discriminatory zone for IRP?
1000-2000 miu/ml for endovaginal imaging
How often does hCG double?
Every 48 hours for the first 6 weeks of a normal pregnancy
What happens to hCG in ectopic pregnancies?
Plateaus or rises at a subnormal level
What happens to hCG with abortions?
Falls to zero
What happens to hCG with gestational trophoblastic neoplasia?
Excessively high levels
How does an obstetrical wheel work?
Align arrow to first day of LMP, other arrows points to EDD
Can also align known gestational age to current date to determine LMP or EDD
What’s Naegele’s rule?
EDD = LMP - 3 mo + 7 days
What are some reasons for doing first trimester sonogram?
Vaginal bleeding of unknown cause, suspected ectopic, estimate gestational age for pts undergoing repeat C-section/induced labor/elective pregnancy termination
Pelvic mass, suspected uterine abnormality, significant uterine size/clinical date discrepancy
Suspected hydatidiform mole, adjunct to amniocentesis or chorionic villus sampling (CVS), IUD localization, suspected multiple gestation
What happens in the gestational/menstrual age week 1-2?
What phase is it?
Proliferative phase
FSH stimulates ovarian follicular development
Estrogen produced by follicles, stimulates endometrial repair
What’s the sonogram appearance of the early and late Proliferative phase (weeks 1-2 gestational/menstrual age)
Early prolif phase: endometrial double-layer thickness 4-8mm
Late prolif phase (periovulatory) triple endometrial appearance, 6-10 mm
What happens in the gestational/menstrual age week 3-4?
What phase is it?
Conceptus period
Ovulation: approx 14 days post LMP, can vary. Stimulated by LH surge, ovum released into peritoneum and swept into ampullary part of tubes
Corpus luteum: LH causes ovarian follicle to form this. MC adnexal mass in 1st trimester. It produces progesterone that peeped and maintains secretory endometrium. Also produces estrogen
During the conceptus period (gestational/menstrual age week 3-4) what’s going on with the endometrium and what’s the purpose?
Secretory phase
Endometrial glands secretion is rich in glycogen, source of nutrients for embryo til placenta takes over around week 12
How does the secretory endometrium look on a sonogram?
Hyperechoic
Thick - 7-14 mm
What does pregnancy cause in the endometrium?
What’s it’s purpose?
Decidual reaction
Increased endometrial thickness and glandular changes caused by progesterone stimulation
Need it for early preg nourishment
It occurs during intrauterine and ectopic pregs
When does fertilization occur in relation to ovulation and LMP? And where
12-24 he after ovulation
Day 14-15 LMP
Usu occurs in ampulla of tubes
What’s a zygote
Fusion of sperm and ovum creates this two cell zygote
What the so a pellucida?
Forms around conceptus zygote, prevents other sperm penetrating
Where do conceptus become a morula and how?
Cells undergo cleavage and develop into a morula while traveling thru tube toward uterus
What’s a morula? What are the individual cells called?
18 cells (cell number doubles but maintains it's size) Individual cells are called blastomeres
When does the morula enter the uterus?
Approx day 17 GA
What’s a blastocyst?
Fluid collects btwn blastomeres of morula, forms fluid filled cyst with clump of cells at one end
Where is the blastocyst located?
In uterine cavity, floats for about 2 days
What happens to the cells of the blastocyst?
What will they form?
Organize into inner and outer cell mass
Inner cells at one end will become embryo (bilaminar disk), yolk sac and amnion
Outer cells: trophoblastic cells, surround the cavity and inner cell mass. Form chorion and placenta
When does implantation occur?
Days 20-23 LMP
6-7 days post fertilization.
What happens to the blastocyst during implantation
Blastocyst sheds zone pellucida to begin implantation
Trophoblasts burrow into decidualized endometrium
When will preg tests be positive?
When trophoblasts burrow into decidualized endometrium for implantation bc they produce hCG
Whats the outer membrane of the gestational sac during implantation?
Chorion (trophoblastic cells)
What’s the chorion frondosum?
Early chorionic villi that attach to endometrium, anchoring the placenta and will become fetal side of placenta
What’s the chorion laeve
Part of the chorion not involved in implantation
What’s the decidua basal is
Maternal part of the placental attachment
What’s the decidua capsularis
Layer of the endometrium that heals over the implanted gestational sac
What’s the decidua Vera (parietalis)
Endometrium not in direct contact with the gestational sac
Next to the decidua capsularis, creates a double echogenic rim known as the double decidual sign (DDS)
When should a double decidual sign (DDS) be seen?
Early pregnancy 4-6 weeks Suggests IUP (intrauterine pregnancy)
When does the amnion, yolk sac and primitive chorionic villi develop?
Around day 23-28 LMP
Where does the amnion form around days 23-28 LMP?
Is it seen on sonogram then?
Btwn bilaminar disk and chorion
Early amnion is not seen well on sonogram, a tiny amnion (2mm) may be seen around week 5.5 gestation
What’s the transient finding of the amnion adjacent to the yolk sac called?
Double-bleb sign
Where does the amnion first expand to and what’s it responsible for?
Surrounds the embryo
Responsible for embryonic folding
When does the amnion become more apparent on ultrasound? Where will it be seen?
Around week 8 gestation
Surrounds the embryo but not in contact with the chorion
When does the amniotic membrane fuse with the chorion?
Week 14-16
What does the amniotic cavity contain?
Amniotic fluid
When does the primitive yolk sac form?
Is it seen on sonogram?
Day 23 LMP
Not seen
When does the secondary yolk sac form?
When is it seen on sonogram
Days 27-28 it forms from the primary yolk sac
Visible on sonogram around week 5.5
What’s the first structure to be seen within the gestational sac? What does it confirm?
Secondary yolk sac
Confirms IUP
What are the 4 fxn of the yolk sac?
- Transfers nutrients
- Hematopoiesis (forms blood cells)
- Angiogenesis
- Forms digestive tract (dorsal part forms primitive gut)
What is the yolk sac connected to and where’s it located?
Connects to the embryonic midgut by the vitelline duct, it’s outside the amniotic cavity
What’s the allantois?
What’s it the source for?
Part of the yolk sac incorporated into the umbilical cord
Source of allantoic cysts (umbilical cord cysts)
In multiple pregs, how many yolk sacs for each amnion?
1/1
What size should yolk sacs measure? What if it’s abnorm?
< 6 mm
Measure inner borders
Abnormalities are assoc with poor preg outcomes
Echogenic or calcified yolk sac is abnormal
Where does the primitive chorionic villi form?
Around entire chorion
What’s the purpose of the primitive chorionic villi?
Invades the decidua basics of the endometrium, anchoring the placenta
Site of transfer of nutrients from maternal to fetal blood
