Lecture 4A Flashcards
When is first trimester assesment
0-13 weeks
if first scan the first trimester assessment is called
Dating US
What is done for first trimester assessment (3)
Assess gestational sac
asses embryo
Assess maternal structures
Patient prep for first trimester assessment
No fasting
Full bladder for tranabdo
Empty bladder transvag
Patient history questions fo first trimester assessment
LMP Positive pregnancy test? Gravidity, Parity, Abortus Is patient having pain or bleeding Patient on meds? Previous c section? Any complications?
Order that embryonic structures become appearant
Decidual rxn
Gestational sac
Yolk sac
Embryo
When does decidual rxn occure
Implantation occurs day 20-23
Size of conceptus at decidual rxn
0.1mm, not visible
What is first reliable sign of intrauterine pregnancy
Gestational sac
What is gestational sac also called
Chorionic cavity
When is the GS visible
4.5-5 weeks
Where is the GS seen within
Decidua
Known as intradecidual sac sign (IDSS)
What must we differentiate GS from
Pseudogestational sac
Decidual cysts
Pseudogestational sac is what
Small amount of fluid within the endometrial cavity between the endometrial layers
Decidual cysts are what
Small cysts that can form within the decidual reaction
Characteristics of true GS
Round or oval Eccentric Directly adjacent t endometrial lining Will develio a yolk sac and embryo Will develop a double decidual sac sign
what can a double decidual sac sign confirm
Intrauterine pregnancy
What is DDSS seen as
2 concentric rings surrounding gestational sac
What does the GS consist of (2)
Decidua parietalis and decidua capsularis
What can the DDSS differentiate
Abembryonic pole and embryonic poke
Mean sac diameter is
The common mode of measurement, averages 3 perpendicular planes
MSD= (L+W+H)/3
GS is measure wher on the walls
Inner to inner
Mean sac diameter is used to calculate
Calculat gestational age (GA) at 5-10 weeks
How old is GA is MSD is 2mm
4 TO 4.5 weeks
When does the yolk sac appear
5.5 weeks
What happens at 6 weeks
Embryo appears adjacent
If GS is larger than 8mm without a yolk sac or larger than 16mm without embryo then it may be a sign of
Early pregnancy failure
Where is the yolk sac seen
Within the GS before the embryo
Yolk sac must be seen latest at MSD of
20mm
Visualization of YS helps confirm
True gestational sac
