embryologic Gestational conception first
Conceptual
age
aka
age
considers
is
first
day
of
pregnancy
.
age
aka
menstrual
age
considers
day
of
last
menstrual
period
is
beginning
of
gestation
.
first
Gestational age aka menstrual age considers day of last menstrual period is beginning of gestation .
Embryo Fetus Zygote
is
the
conceptus
12
days
after
conception
,
during
implantation
process
is
the
conceptus
from
time
of
implantation
until
end
of
10th
week
menstrual
age
is
the
conceptus
after
first
10
week
s
Fertilization zygote 14 Ampulla cleavage luteum corpus zona progesterone pellucida morula ovulation
During
28
-
day
menstrual
cycle
,
a
mature
ovum
typically
released
on
day
this
is
called
.
The
follicle
that
released
it
forms
the
and
begins
secreting
.
occurs
within
the
distal
fallopian
tube
(
)
1
to
2
days
after
ovulation
.
Fertilized
conceptus
is
now
called
a
which
includes
an
egg
nucleus
,
sperm
nucleus
,
and
a
membrane
surrounding
it
called
the
.
The
zygote
undergoes
rapid
cellular
division
to
form
16
-
cell
this
dividing
is
called
.
12 primary 32 enzymes decidua placenta wall blastocyst Secondary coelom hCG proliferation differentiated 23 embryo trophoblastic
Further
cell
proliferation
brings
morula
to
stage
and
it
typically
enters
uterus
4
to
5
days
after
fertilization
containing
+
cells
The
cells
are
not
just
copies
of
the
originals
,
they
have
now
into
new
cells
that
will
form
into
new
human
parts
.
The
"
inner
cell
mass
"
forms
the
while
the
outer
cells
along
the
perimeter
will
become
the
and
secrete
hCG
causes
uterine
endometrium
to
convert
to
,
a
glycogen
rich
mucosa
that
nourishes
early
pregnancy
.
Implantation
into
uterine
decidua
completed
within
days
after
fertilization
During
implantation
,
produced
by
trophoblasts
"
eat
into
"
decidual
tissue
.
This
creates
spaces
for
trophoblastic
cell
.
At
end
of
implantation
process
,
zygote
has
buried
itself
within
one
of
uterus
.
Implantation
bleeding
-
when
this
process
results
in
light
vaginal
bleeding
about
same
time
as
expected
menstrual
period
.
Within
the
implanted
conceptus
,
the
inner
cell
mass
matures
into
the
embryonic
disc
(
future
embryo
)
and
primary
yolk
sac
.
At
approximately
days
menstrual
age
,
yolk
sac
is
pinched
off
by
extra
embryonic
,
forming
the
secondary
yolk
sac
.
yolk
sac
is
the
yolk
sac
seen
sonographically
throughout
first
trimester
.
35 Cardiovascular C 10th Embryonic human flat heartbeat
Phase
is
between
weeks
4
and
10
system
undergoes
rapid
development
,
with
initial
occurring
between
5½
and
6
weeks
.
Embryo
appearance
changes
from
,
disk
-
like
configuration
to
-
shaped
structure
and
develops
a
recognizable
appearance
During
this
period
,
crown
-
rump
length
(
CRL
)
develops
rapidly
,
measuring
mm
by
end
of
week
.
organs larger Fetal half
Weeks
11
and
12
constitute
the
beginning
of
this
period
when
there
is
continued
growth
of
and
structures
formed
during
embryonic
period
.
The
fetal
head
is
disproportionately
than
rest
of
fetus
(
the
same
size
as
the
body
)
,
constituting
one
of
CRL
.
chorionic Ectopic 5 capsularis echogenic basalis embryo trophoblastic Incorrect myometrial Qualitative capsularis Incorrect 3000 chorionic >3 fundal trophoblastic later Smooth decidual slowly basalis Embryonic Multiple 1 eccentrically
hCG
:
urine
results
are
positive
or
negative
Quantitative
hCG
:
provides
specific
levels
of
hCG
in
blood
.
Provide
a
specific
number
value
.
Normal
gestational
sac
is
expected
to
be
seen
when
hCG
level
is
mIU
/
ml
or
greater
.
With
Down
?
s
Syndrome
hCG
levels
plateau
and
fall
more
Greater
than
expected
hCG
levels
seen
with
dates
(
further
along
than
expected
)
,
Gestational
disease
&
gestations
Lower
than
expected
levels
of
hCG
associated
with
dates
(
not
as
far
along
as
expected
)
,
pregnancy
,
demise
/
abnormal
IUP
/
impending
miscarriage
.
Gestational
Sac
aka
sac
is
the
first
visual
evidence
of
IUP
during
week
.
It
appears
as
1
-
to
2
-
mm
sac
with
ring
having
sonolucent
center
which
represents
the
cavity
.
Circumferential
echogenic
rim
seen
surrounding
gestational
sac
represents
tissue
and
associated
reaction
Echogenic
ring
around
gestational
sac
divided
into
o
Decidua
-
Portion
on
or
burrowing
side
of
conceptus
.
o
Decidua
-
Villi
covering
developing
.
The
double
decidual
sac
sign
is
the
interface
between
decidua
and
decidua
.
Normal
gestational
sac
features
o
placed
in
relation
to
endometrial
cavity
,
secondary
to
its
implantation
o
location
noted
o
Round
or
slightly
oval
in
shape
o
contours
o
Decidual
wall
thickness
mm
?
Gestational
sac
grows
at
predictable
rate
of
mm
/
day
in
early
pregnanc
y
5½ 12 12 15 Yolk nutrients stalk amniotic 5 10 8 6 >12 chorionic endoderm Hematopoiesis >90%
Sac
should
be
seen
when
mean
sac
diameter
is
mm
.
Routinely
visualized
between
and
weeks
of
gestation
o
Provide
to
developing
embryo
o
:
Formation
of
blood
o
Development
of
embryonic
At
approximately
weeks
gestation
,
with
amniotic
cavity
expansion
,
the
yolk
sac
,
which
lies
between
and
membranes
,
detaches
from
yolk
.
?
Visualization
of
yolk
sac
predicts
viable
pregnancy
in
of
cases
.
?
Failure
to
visualize
yolk
sac
,
with
minimum
of
-
mm
MSD
,
using
transvaginal
sonography
,
is
suspicious
for
abnormal
pregnancy
.
o
Transabdominal
studies
have
shown
that
yolk
sac
should
be
seen
within
mean
sac
diameters
of
to
mm
and
should
always
be
visualized
with
mean
sac
diameter
of
20
mm
.
?
Normal
diameter
should
not
exceed
mm
measured
from
inner
edge
to
inner
edge
?
Typically
,
yolk
sac
resorbs
and
is
no
longer
seen
sonographically
by
weeks
.