Chapter 52- Fetal Measurments Flashcards
First trimester measurements
CRL, MSD
2nd/3rd trimester measurements
- Head circumference(HC)
- Bi Parietal Diameter(BPD)
- Femur Length (FL)
- Abdominal Circumference (AC)
The first and most widely accepted means of measuring the fetal head and estimating fetal age in the 2nd trimester
BPD
BPD should be measure in _____ plane
Transverse
BPD is measured at what level
Midline— thalamus, CSP, midline falx
For BPD: calipers should be placed…
Outer edge to inner edge
HC is imaged/measure in ____ plane
Transverse, same level as BPD
Measurement from occipital bone to frontal bone
OFD
Head is SHORTENED in the transverse diameter(BPD) and ELONGATED in the AP diameter(OFD)
Dolichocephaly
Can cause underestimation of fetal age
Dolichocephaly
Head is ELONGATED in the transverse diameter(BPD) and SHORTENED in the AP diameter (OFD)
Brachycephaly
Can cause over estimation of fetal age
Brachycephaly
Cephalic index formula:
CI= (BPD/OFD) x 100
Normal cephalic index
80% + or - 1%
Range of normal cephalic index
75-85 %
CI of _____ suggests brachycephaly
Greater than 85%
CI of _____ suggests dolichocephaly
Less than 75%
Abdominal circumference should be measured _____
Transverse
Abdominal circumference should be measured at the level of
The liver where the umbilical vein branches into the left portal sinus
The umbilical vein and portal vein form a ____
J-shape
Kidneys should NOT be seen on the plane for abdominal circumference
True
Has the largest reported variability & is more affected by growth disturbances
Abdominal circumference
Most widely measured and easiest to obtain
Femur length
If two week or greater difference between FL and all other measurements, what should be done?
Measure all long bones
Short long bones are associated with
Trisomy and dwarfism
Out of the tibia and fibula which is larger
Tibia
Tibia is ____ to the fibula
Medial
Humerus is usually found closest to the
Fetal trunk
Out of the ulna and the radius which is larger
Ulna
Ulna is _____
Medial
Radius is ____ side
Thumb side
Measuring what structure is more accurate than the BPD for measuring fetal age
Measuring the cerebellum
Why is the cerebellum more accurate than the BPD for measuring fetal age?
Posterior fossa is not affected by some conditions that affect fetal growth
A ____ shaped cerebellum is associated with spina bifida
Banana
Cerebellum should have a _____ shape
Peanut or dumbbell
Cerebellum
Widest _____ diameter should be measured
Trans
