Class 10: U/S in 1st Trimester Flashcards
what is ovulation?
when an ovary releases an ovum
what happens if fertilization of an ovum occurs?
corpus luteum cyst stays & the endometrium grows
what happens if fertilization of an ovum doesn’t occur?
estrogen & progesterone levels decrease, corpus luteum regresses, and menstruation starts
how long does sperm remain viable in the female reproductive tract?
24-72 hours
how much sperm is considered clinical infertility?
less than 20 million sperm/ml
term for the functional maturation of sperm?
capacitation
what is the process of capacitation?
the process where the sperm’s glycoprotein coat is removed by substances secreted by FT & UT
what happens when the sperm’s glycoprotein coat is removed?
sperm becomes hyperactive & acrosomal reaction occurs when in contact with ovum
what does the acrosomal reaction do?
acrosome from sperm breaks down outer membrane of ovum to penetrate ovum
where does fertilization most commonly occur?
ampulla of FT
when does fertilization occur?
about 24-36 hours after ovulation
when does implantation occur?
about 6 days after ovulation
how many chromosomes are in a zygote?
46 chromosomes
what is a zygote?
sperm fertilizes an ovum, merge genetic content to make zygote
how many cells are in a morula cell?
16 cells
the ____ implants in the uterine cavity
blastocyst
what is the trophoblast of the blastocyst?
the outermost layer of cells
what is the outer layer of the trophoblast?
synctiotrophoblast
what is the inner layer of the trophoblast?
cytotrophoblast
what hormone does the trophoblast produce?
HCG
what does the trophoblastic tissue form to invade the endometrium?
chorionic villi
what is the fetal side of the placenta called?
chorionic site
what does the inner cell mass of the blastocele form into?
embryo, amnion, and yolk sac
what does the blastocyst become?
embryo
what is the gravid endometrium become?
the decidua
3 layers of the decidua?
- decidual basilis
- decidual capsularis
- decidual parietalis/vera
where is the decidua basilis?
the thickened endometrium at the site of implantation
the decidua basilis is the fetal side of the placenta. T/F?
false; it is the maternal side
what is the decidua capsularis?
endometrium that forms & thickens around the chorion away from the placenta
which decidual layer lines the gestational sac?
decidua capsularis
which decidual layer projects into the uterine lumen?
decidua capsularis
which decidual layer lines the uterine cavity?
decidua parietalis/vera
what is the double decidual sac sign?
the interface bw the decidua capsularis & parietalis
the ____ sign is a sign of viable gestation
decidua sac sign
what are the 3 fetal membranes?
amnion, chorion, yolk sac
2 functions of the yolk sac?
- provides nutrients for embryo
- hematopoiesis
how does the endometrium look like in the first trimester on US?
lush echogenic endometrium that represents the double decidual sac sign
1st US appearance of an IUP?
gestational sac
1st structure seen in the GS?
secondary yolk sac
2nd structure seen in GS?
embryo
shape of the GS on US?
round, oval, tear drop
location of the GS within the UT?
at the UT fundus or eccentrically placed position in mid-UT
what is the decidual wall thickness?
> 3 mm
what is the first lab value to be tested for pregnancy?
HCG levels
what are the 2 preps for HCG levels?
- 1st IRP: 1st international reference preparation
- 2IS: 2nd international standard
which prep has HCG quantities double the other?
1st IRP
(2)(2IS)=IRP
the GS should be seen at 4.5 weeks (TV) from LMP when HCG reaches 2IS levels of ___ mIU/ml
500 mIU/ml
The GS should be seen at 6 weeks (TA) from LMP when HCG reaches 2IS levels of ___ mIU/ml
1800 mIU/ml
an unseen yolk sac TV when the MSD is ___ is abnormal
> 8mm
an unseen yolk sac TA when the MSD is ___ is abnormal
> 20 mm
which plane do you measure the MSD on?
both SAG & TRV
MSD formula?
MSD=LWH/3
the MSD is used up to ___ of gestation +/- ___
8 weeks +/- 2 weeks
which measurement is the most accurate measurement in pregnancy?
CRL
the CRL can be used. up to ___ of gestation
12 weeks
what does the MSD measure?
gestational sac
what does the CRL measure?
embryo
what measurement detects cardiac activity of the fetus?
fetal heart motion – m-mode
what is the vitelline duct?
a duct that connects the midgut & yolk sac
what 2 structures merge to form the umbilical cord?
vitelline duct & allantois
when does the heart start pumping?
21 days after conception
what size is the embryo when we are able to detect cardiac activity?
embryo is 5+ mm
when does herniation of the gut occur?
7-8 weeks
when does the herniated gut return to the body?
9-10 weeks
when is herniation of the gut abnormal?
after 12 weeks
the embryo should be seen TA when MSD measures ____
25+ mm
the embryo should be seen TV when MSD measures ___
16+mm
what weeks is the conceptus considered an embryo?
1st day of LMP to week 10
what weeks is the conceptus considered the fetus?
week 10 to birth
3 ways to date the conceptus in the 1st trimester?
- patient’s LMP
- MSD
- CRL
what is the normal order of structures seen within the early GS for the amnion, embryo, and yolk sac?
- yolk sac
- embryo
- amnion
it may be normal to see an embryo without amnion. T/F?
true
it may be normal to see amnion without an embryo. T/F?
false – may indicate a nonviable/anembryonic pregnancy
what is another name for a failed IUP?
miscarriage
what is considered a failed IUP?
a gestational sac without a yolk sac
a GS without a yolk sac when MSD measures ____ TV is considered a miscarriage
> 8 mm
a GS without a yolk sac when MSD measure ____ TA is considered a miscarriage
> 20 mm
how is a blighted ovum diagnosed?
a GS without fetal pole or yolk sac
another name for a blighted ovum?
anembryonic pregnancy
3 clinical findings for a blighted ovum?
- vaginal bleeding
- low HCG levels
- decreasing S&S of pregnancy
a GS without an embryo with an MSD of ___ TV is considered an anembryonic pregnancy
16 mm
a GS without an embryo with an MSD of ___ TA is considered an anembryonic pregnancy
25 mm
US can detect a heartbeat when an embryo is ___ mm
> 5mm
what is considered an abortion/spontaneous abortion/miscarriage
termination of pregnancy < 20 weeks gestation
what is a complete abortion?
all products of conception are expelled
US appearance of complete abortion?
normal thin endo, empty UT, no corpus luteum cyst
clinical findings of complete AB?
quickly declining HCG
bleeding & cramps
what is an incomplete abortion?
there are still retained POC in the UT
U/S appearance of an incomplete abortion?
thick, irregular endo
fluid in endo
embryonic parts with or without shadowing
what is a missed abortion?
an embryo without cardiac activity (no flow w CD) and not expelled
US appearance of GS & cervix with missed AB?
GS is intact & closed cx
what is a threatened abortion?
patient presenting vaginal bleeding with closed cx prior 20 weeks
a threatened abortion is clinical findings only. T/F?
true
US appearance of threatened AB
normal appearance with intact GS & live embryo. cervix is closed
what is the length of a normal cervix?
3-4 cm
what length is considered an incompetent cervix?
<2.5 cm
other names for inevitable abortion?
imminent abortion/abortion in progress
what is inevitable abortion?
when IUP is moving towards the cervix; dilated cervix; patient has profuse bleeding
what is a septic abortion?
abortion due to infection
what is therapeutic abortion?
termination of pregnancy by D&C or surgical means
difference between therapeutic vs elective abortion?
therapeutic is due to mom or fetus’ life in danger; elective is the mom’s choice
what is habitual abortion?
repeated SAB
lab values for all types of abortion?
decreasing HCG levels
what is the most common cause off bleeding in the 1st trimester?
subchorionic hemorrhage
what is another name for subchorionic hemorrhage?
perinatal hemorrhage
when can a subchorionic hemorrhage occur?
at the time of implantationg
where does a subchorionic hemorrhage occur?
between the uterine wall & GS/chorion
S&S of subchorionic hemorrhage?
spotting or bleeding with or without contractions
2 outcomes for subchorionic hemorrhage
- spontaneously regress
- spontaneous abortion if large hemorrhage