Landmarks, Measurements Of BPD

#Biparietal Diameter.
#Gestational Diabetes.
#Microcephaly.
#Head Circumference.
#Femur Length.
Know How the Baby Grows!!
The biparietal diameter is one of the
basic biometric parameters used to
assess fetal size.
Bipariental diameter, together with head circumference, abdominal circumference, and femur length are computed to produce an estimate of fetal weight in the second trimester.
This may be extrapolated to an estimate of gestational age and an estimated due date EDD. Biparietal diameter and fetus has been reported to correlate well with gestational age.
Bipariental diameter aside from being used to estimate gestational age, fetal growth is also helpful in the detection of fetal abnormalities. The biparietal diameter remains the standard against which other parameters of gestational age assessment are compared. The anatomical landmarks used to ensure
the accuracy and reproducibility of the
measurement include:
1. A midline falx. The falc cerebri is a large sickle-shaped, tinfolding of the inner menbrane layer of the duramater and lies in the midline of the skull.
2. The thalami. Symmetrically positioned on either side of the falx.
3. Visualization of the septum pellucidum at one third the frontal occipital distance. That is at each examination, bipariental diameter images were acquired in the transthalamic plane where the landmarks consist of the calvum septum pellucidum, thalami and absence of the cerebellum.
Measurement technique of the
bipariental diameter includes:
1. On an axial plane that traverses the
thalami and calvum septum pellucidum. The transducer must be perpendicular to the central axis of the head and thus the
hemispheres in calvaria should appear
symmetric the calipers should be placed
at the one outer edge of the near calvarial wall to inner edge of the far calvarial wall.
The cerebral hemisphere is noted in the plane of the image.
A wrong measurement plane can produce
errors up to 20 millimeters. The
biparental diameter measurement is
obtained from Outer skull bone to lnner
skull bone, leading Edge to Leading Edge
perpendicular to the falx at the
maximum diameter.
A leading edge to leading edge measurement or middle to middle measurement is acceptable.
The bipariental diameter should be measured as early as possible after 13 weeks for dating, interpretation.
Bipariental diameter has been shown to be accurate in predicting gestational age from 14 to 20 weeks. The variability increases after this time.
Bipariental diameter may also be influenced by factors such as abnormalities of head
shape, breech presentation or multiple
gestations.
Head circumference may be a more reliable measurement if there is variant head shape.
If your baby's biparietal diameter measurement is larger than expected it could signal that a health issue such as gestational
diabetes.
A low bipariental diameter can be an indication to monitor fetal head growth. Microcephaly can be a concern for women who may have been exposed to the zika virus. Also considered macrocephaly.
The biparental diameter can be smaller and sometimes much smaller than is expected in fetuses with flatter heads. If the head really looks flat on the scan check the head circumference and record the findings if the value is within the normal range then most likely the discrepancy is due to a flat head. Monitor the growth of the fetal head with the circumference from then on the cephalic index will also be useful. If the value is below 74 the head is considered excessively flat.
In cases of microcephaly, the biparenta| diameter is usually at least two standard
deviation below the mean.
The biparental diameter in third trimester is not reliable and be useless when the patient passed 30 weeks in those cases the biparental diameter has to be side with other measurements.
when we take it in later trimesters to emphasize the normal growth of fetus and avoid wrong measurement of ultrasound, the biparental diameter is useful for
dating a pregnancy and an estimating
intrauterine fetal weight and weight
equation. The latter has the advantage that all three measurements bipariental diameter, head circumference and
ventricular Atrium can be taken in the
same section. The calipers should be
placed at the widest part of the skull
perpendicular to the midline echo other
than that its value is limited and can
sometimes be misleading in the
assessment of growth in the fetus if it
is the sole measurement taken for
interpretation.
Thank You.

[@KPSinghCardiosonologist]

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