DMS| OBGYN| CH. 18 fetal age and size of 2nd and 3rd Trimester
OFD
-Occipital frontal diameter -outer to outer edge of the middle of the frontal bone adn the occipital bone echoes
binocular measurement
-distance from the outer edges of the left and right fetal eyes
cephalic index
-ratio of the BPD to the OFD -used to determine if the shape of the TRV fetal skull can aloow a reliable BPD measurement
Normal conception usually takes place ____ after LMP.
2 weeks
Birth normally occurs ____ after LMP
40 weeks
biparietal diameter
AKA BPD Refers to the greatest transverse diameter of the head which extends from one parietal bone to the other.
brachycephalic
BPD is wide, FOD is short, CI is greater than normal
Which measurements are recommended to take for every exam as a minimum standard?
Head measurements (BPD and HC) Abdominal circumference at least one long bone extremity
APD
antero-posterior abdominal diameter
_____ determines biometric accuracy of a sonogram.
axial and lateral resolution
Which resolution has the least measurement error?
axial resolution
The difference between gestational age and conceptual age
calculation using LMP rather than date of conception
hockey stick or j view
confluence of the umbilical and portal veins in the fetal liver preferred view of the AC
superior to the AC measurement
fetal heart
inferior to the AC measurement
fetal kidneys
The AC measurement is more important for what?
fetal weight and health than fetal age
low birth weight and intrauterine growth restriction is associated with
higher incidences of neonatal morbidity and death
Reason early embryo measurements are more accurate
individual differences have not yet become evident
Variations in any single parameter's prediction in age will usually be:
less than give or take 10%
dolichocephalic
long and narrow head short BPD adn low CI
axial resolution involves:
measurements along the axis or path of the beam (A for axis and axial)
lateral resolution involves:
measurements transversely at right angles to the beam direction. (perpendicular)
femur length
most commonly used parameters and most reliable after 14 week's gestation
abdomen to head ratio
normally 1:1
all measurements of the AC are from:
outer skin lines
the femur is measured from what to what?
proximal end near the femoral neck to the distal epiphyses
abdominal circumference measurement
reflects the development of abdominal organs
What should be visible for a BPD measurement?
thalamus and cavum septi pellucidi
Multiple Fetal Parameter (MFP)
the average of BPD, HC, AC and FL that gives the most accurate estimation of fetal age
BPD measurement should be made perpendicular to:
the interhemispheric fissure (midline) and should include the thalamus.
the more measurements obtained and averaged, ___.
the more accurate the fetal age estimate
Obtain the AC at the level of:
the umbilical vein junction with the portal vein and perpendicular to the spine
Estimated date of confinement (EDC) Estimated delivery date (EDD)
two terms to indicate the expected birth date
Head circumference (HC) measurement
use the same image as BPD should include the cavum septi pellucidi, interhemispheric fissure and thalamus take the outer-to-outer axial measurement and the outer-to-outer frontal to occipital measurement
