1st Trimester Flashcards
After ovulation, conception usually occurs within ____
24 hours
Sperm + ovum =
Zygote
Zygote forms into the ___
Morula
Morula becomes the ___
Blastocyst
Outer layer of blastocyst is made up of _____ cells
Trophoblastic cells
The cells that produce hCG
Trophoblastic cells
Inner part of blastocyst develops into
Embryo, amnion, umbilical cord, yolk sacs
Trophoblastic tissue develops into
Placenta and chorion
Blastocyst begins to implant into the decidualized endometrium by day ___ of menstrual cycle
Day 20-21 of menstrual cycle
Implantation is complete by day
Day 28
Blastocyst connects to endometrium via small projections called:
Chorionic villi
Chorion
Gestational sac
HCG is detected in the maternal blood as early as
23 days menstrual age
Gestational sac should be visualized transvaginally when hCG levels are
Between 1000 and 2000 mlU
Normal hCG levels double every ____ hours in the 1st trimester
48 hours
In first trimester, thermal index should be kept below ____
1
Decidual reaction
Endometrium becomes thick and echogenic in preparation for implantation
First definitive sonographic sign of an IUP
Gestational sac
To distinguish gestational sac vs pseudogestational sac, look for
Double sac sign or double decidual sign
Double sac/ double decidual sign
Two rings surrounding a true gestational sac. Inner(capsularis) outer(parietalis)
What sign is this
Double sac sign or double decidual sign
The short arrows are pointing to
Decidua capsularis
The long arrows are pointing to
Decidua parietalis
Earliest measurement to date pregnancy
Mean Sac Diameter(MSD)
Adding ____ to the MSD, in mm, is an estimate to gestational age
By adding 30 to MSD
MSD of ____ that doesn’t have a fetal pole is abnormal
> 25 mm
First structure within gestational sac
Secondary Yolk sac
Yolk sac produces
AFP
Yolk sac is connected to the embryo by
Vitelline duct
Vitillene duct aka
Omphalomesenteric duct
Yolk sacs role in early pregnancy
Nutrient transfer and hematopoiesis
Vitelline/omphalomesenteric duct contains ___ vein and ____ artery
1 vein and 1 artery
Yolk sac is within the ___ cavity
Chorionic cavity
Gestational sac contains ____ cavities
Two cavities. 1. Chorionic 2. Amniotic
Amniotic cavity contains
Amniotic fluid and embryo
Amnion and chorion are fused by ____ weeks
16 weeks
Embryo will grow at a rate of ____ per day
1mm per day in first trimester
Limb buds are identified by week
Week 7
Cystic structure noted within early fetal head
Rhombencephalon
Rhombencephalon develops into the
4th ventricle
What is the arrow pointing to
Rhombencephalon
Physiologic bowel herniation begins at ___ weeks
8 weeks
Physiologic bowel herniation is typically resolved by week
Week 12
This is an image of a 11.5 week fetus. What do you suspect the arrow is pointing to?
Physiologic bowel herniation
Decidua basalis is the
Maternal contribution of the placenta
Chorion frondosum is
The fetal contribution of the placenta
Most common anomalies associated with increased NT
Trisomy 21,18, Turner syndrome, CHF
NT is measured between _____ weeks
11 weeks - 13 weeks 6 days
NT is measured when he CRL measures ______
Between 45-84 mm
Abnormal NT measures
> 3mm
