3. BPD
Correct levels
2 views: lateral ventricle view, thalamic view
More accurate than CRL +/- 5 days
Maximum diameter of transverse section of fetal
skull at level ofthe parietal eminences
4. BPD
Lateral ventricle view:
Rugby shaped skull
Long midline equidistant prox-distal skull echoes
Cavum septum pellucidum (CSP) bisecting midline
Two anterior horns of lat ventricle- symmetrical
Post horns of lat ventricle- symmetrical
10. BPD
Estimating GA from BPD:
Not to rely on estimates of GA from US software
GA should not be made from single parameter
Different charts
GA and growth require different charts and
charting
12. BPD
Confirming or assigning GA:
If LMP and earlier dating 1st trimester US matches- stick
to this date
2nd trimester US is only for growth and not for dating
If the 2nd trimester US is the first scan done error is
greater:
below 24w +/- 2 w
After24w >3w
16. Abdominal circumference
Landmark features:
Circular section with ribs
One vertebra -triangle of 3 white
spots
Umbilical vein (short) - hockey
stick
Stomach left abdomen
Good for dating of pregnancy
Sensitive to growth aberrations
Fetal weight assessment
19. Femur length
As accurate as BPD for GA
From 12w to term
Slide probe caudally from AC section till iliac bones
Cross section of 1 femur seen
Upper femur for measurement
Rotate
25. Placental localisation
Cervical canal directly posterior to bladder
Lower edge >5 cm from internal os
<5cm low lying
Placentae previa after 28w
Braxton hicks
29. Amniotic fluid volume
Produced by fetal kidneys (urine) and removed by fetal
bowel (swallowing)
Oligohydromnios = decreased volume
Polyhydromnios = increased volume
Measurements : Visual
Max vertical depth 3cm
AFI - <5cm =oligo, >25cm = poly
30. Fetal anatomy
assessment
Dependant on sonographer- correct images,
correct interpretation
Go through all-complete coverage--> then no
major abnormalities will be missed
E.g.After 12w - anencephaly
41. Fetal anatomy
assessment
Fetal heart:
moderator band = right ventricle
2 ventricles/ walls of equal size
2 atria / walls of equal size
apex point left of fetal chest
foramen ovale moving in left atrium
pulmonary veins entering left atrium
motion of mitral valves (left side) regular
motion of tricuspid valves (right side) regular
'offset crux' of the heart: AV valve should not insert into IV septum at the same level
intervertebral septum should be complete
44. Fetal anatomy
assessment
eg: (i) regurgitation of tricuspid valve - enlarged right atrium
(ii) hypoplastic left heart syndrome - left ventricle small
(iii) coarctation - right ventricle enlarged
(iv) Ebstein anomaly - enlarged right atrium due to
abnormal implantation of tricuspid valve
normal IV septum - excludes VSD
normal offset crux - exclude AVSD
Both ASD & AVSD are assessed with trisomy 21
46. Fetal anatomy
assessment
Demonstrate left ventricle: continuity of IV septum--> ant
wall of aorta--> aortic valve & short section of ascending
aorta
Abnormal AOT:
Overriding aorta
Aortic stenosis
Double outlet right ventricle
Fallot's tetralogy
47. Fetal anatomy
assessment
Pulmonary artery outflow
tract:
Demonstrate:
Right ventricle
Pulmonary valve
Main pulmonary artery
abnormal in double outlet
right ventricle &
pulmonary stenosis
52. Fetal anatomy
assessment
Cleft lip and palate:
Incidence 1:700 births
80% isolated incidence
But association with trisomy 13 &18, anti
epileptics drugs
