fetal and obstetric imaging Flashcards
indications of utz
locating pregnancy identifying number of embryos aiding in prenatal diagnosis estimating gestational age evaluating suspected trophoblastic ds
what to look for in utz?
gestational sac, shape, location and number presence/absence of embryo CRL & YS presence/absence of fetal cardiac motion w/ m-mode measure YS AP diameter, check shape evaluate for subchorionic hemorrhage evaluate adnexal mass document presence/absence of free fluid document length & status of cervix measure nuchal translucency
utz findings of early pregnancy
GS MSD YS fetal pole CRL
confirming intrauterine gestation (3)
double decidual sign
intradecidual sign
double bleb sign
first sign of early pregnancy on TVS at approx. 3-5 wks when MSD is 2-3mm
GS
true GS can be distinguished from pseudogestational sac by?
normal eccentric location and embedded in endometrium
double decidual sign is seen at _wks?
4.5-5 wks
YS is seen at _wks?
5.5 wks
discriminatory hCG with TVS vs TAS
TVS: 1000-2000 IU/L
TAS: >6500 IU/L
MSD is seen at _wks?
3 wks
MSD >25mm w/ absent fetal pole interpretation
pregnancy failure
MSD 16-24mm w/o embryo interpretation
suspicious pregnancy failure
MSD 8mm, YS should be visible, absence of YS is an indication of pregnancy failure, T or F?
false (absence of YS is not an indication of pregnancy failure)
first anatomical structure identified w/in GS
YS
site of initial hematopoiesis
YS
YS involutes at _wks and undetectable after _wks
11 wks
14-20 wks
appear circular thick-walled echogenic structure w/ an anechoic center w/in GS but outside amniotic membrane
YS
YS is seen in TVS at _wks while in TAS at _wks
TVS: 5.5 wks (MSD 8-10m)
TAS: 7 wks (MSD 20mm)
first direct imaging manifestation of fetus
fetal pole
seen as thickening on the margin of YS
fetal pole
fetal pole is seen in TVS at _wks while in TAS at _wks
TVS: 6 wks (MSD >16mm)
TAS: 6.5 wks (MSD >25mm)
most accurate estimation of gestational age in early pregnancy
CRL
CRL is used as primary measure of gestational age at _wks
7-13 wks
cardiac activity should be present in embryo w/ CRL _mm
> 7mm
findings confirming dx of IUP
DDS at 4.5-5 wks
GS + YS at 5 wks
GS + YS + embryo at 5.5-6 wks
CRL>5mm + FHT
initially eccentric, rounded or oval fluid filled collections seen at 4.5-5 wks
DDS
visualization of GS containing YS & AS giving appearance of two bubbles
DBS
threshold & discriminatory level of IDSS
T: 24 days AOG
D: 47 days AOG
this occurs when there is perigestational hemorrhage & blood collects between uterine wall and chorionic membrane.
frequent cause of 1st & 2nd trim. bleeding
subchorionic hemorrhage
this is the normal fluid-filled SQ spaceidentified at the back of the fetal neck during late 1st trim. & early 2nd trim.
nuchal translucency
conditions associated w/ NT thickening
aneuploidy trisomies turner syndrome non-aneuploidy structural defects & syndromes congenital heart ds noonan syndrome congenital diaphragmatic herniation omphalocele skeletal dysplasia smith-lemli-opitz syndrome VACTERL association miscarruage Parvo B19
at what wks is considered a routine investigation advised for NT scan?
11-13 wks
what are the 3 traditionally used factors to calculate the risk of trisomies
CRL
NT
FHR
what are the 3 additional markers used to increase detection rate & reduce false-positive rate
nasal bone
DV flow
tricuspid flow
most accurate reflection of gestational age in 2nd trim.
BPD
BPD low for GA interpretation
dolicocephaly
BPD high for GA interpretation
brachycephaly
correct plane for BPD & HC must include the ff (3)
cavum septum pellucidum
thalamus
choroid plexus in atrium of lateral ventricles
reflects growth of intraabdominal organs as well as fetal weight/size
AC
AC measures peripheral circumference of fetal abdomen excluding the SQ tissue, T or F?
false (including the SQ tissue)
landmarks of AC (3)
portal sectioon of UV
stomach
spine
it serves as monitor for growth of long bones
FL
placenta can be seen as early as _wks in TVS
8 wks
normal placental aging is by appearances of? (2)
hypoechoic areas & calcifications
grade of placenta w/c appears as relatively homogenous in echotexture & retroplacental space is hypoechoic
normal placenta
grade of placenta w/c appears w/ small diffuse calcifications randomly distributed in placenta w/ subtle indentations w/in the chorionic plate
grade 1
grade of placenta w/c appears w/ larger calcifications & large indentations along the chorionic plate
grade 2
grade of placenta w/c appears w/ complete indentations along the chorionic plate & more irregular calcifications
grade 3
this fluid protects fetus from injury; allows growth & fetal mvmt; and essential for normal lung maturation
amniotic fluid
oligohydramnios is defined as AFI below?
5cm
causes of oligohydramnios
IUGR
urinary tract abnormalities
PROM
postterm
polyhydramnios is associated with?
maternal DM
GI & CNS anomalies
lethal skeletal dysplasia
chromosomal anomalies
polyhydramnios is defined as AFI more than?
20cm
2nd trim. utz findings
fetal number (amniocity & chorionicity) fetal cardiac activity fetal presentation placental location, appearance AFV GA assessment fetal wt fetal anatomical survey eval of maternal uterus, adnexa, & cervix
FL/AC >23.5 suggests?
IUGR
FL>AC suggests?
growth retarded baby