Ultrasound in second trimester of pregnancy, diagnostic imaging diagnosis imaging of third trimester of pregnancy , fetal ultrasound

1. USG IN OB & GY
(2ND TRIMESTER)
Ref- Ultrasound in Obstetrics and Gynecology
A practical approach
First edition
Editor- Alfred Abuhamad, MD

2. 2ND TRIMESTER
• Refer 14 -28 week of gestation
• At 16 wk , basic anatomy survey is difficult than later gestation when
portable usg is used and in obese women
• But dating scan at 25 week is less precise than earlier gestation

3. MAIN OBJECTIVE
• Date of pregnancy
• Fetal anatomy
• Placenta location
• adnexae

4. FETAL BIOMETRY
• Fetal age ( gestation/dating) and size ( fetal weight)
• According to this ref text book, pregnancy should not be re-dated if a
prior appropriate USG established pregnancy date
• Re-dating on the basic of 2nd trimester should only be perfprmed if the
woman has not undergone any earlier USG

5. FETAL BIOMETRY
(RESULT IN CHANGE IN EDD)
• 14 wk to 15+6 week gestation- discrepancy of 7 days – change in EDD
• 16 wk to 21+6 week gestation- discrepancy of 10 days- change in EDD
• 22 wk to 27+6 week gestation- discrepancy of more than 14 days –
change in EDD

6. BPD
• Cross section of fetal head at
thalami
• Correct level – falx, thalami,
sym of both cerebri, cavum
sepatae pellucici, insula

7. BPD
• BPD – caliper position ( outer and
inner)
• At thalami level
• 90º with the midline falx
• Widest possible
• In 3rd trimester, fetal head is
engaged, BPD measured from
coronal plane of head

8. HC
• Same plane as BPD
• Ellipse method, 2 diameter method
and trace method
• Ellipsoid is more preferred , lest
error
• Tracing the outer edge of fetal
cranium, perpendicular to midline
falx

9. AC
• Circular cross section of abdomen ( as
circular as possible)
• Spine seen on cross section ( 3 or 9
o’clock , avoid 6 or 12 o’clock)
• Stomach bubble
• Intrahepatic portion of umbilical vein
at portal sinus level
• Fetal ribs on laterally
• Kidneys not be visualized

10. AC
• Outer surface of the skin line ,
at he level of rib end
• Ensure to include the outer
edge of the skin contour with
the measurement

11. FL
• Whole diaphysis should displayed on
the screen
• Measure longest visible diaphysis
without including distal femoral
epiphysis
• Should exclude triangular spur
artefacts

12. ESTIMATING FETAL WEIGHT
• More accurate in 2nd trimester than third trimester
• Lesser clinical relevance in 2nd trimester
• Macrosomia is not very accurate and error can exceed 10 %

13. FETAL ANATOMY
• Head ( lateral ventricle , choroid plexus, midline falx, cavum sepatae
pellucidi, cerebellum, cistern magna and upper lip)
• Chest ( heart and LVOT and RVOT)
• Abdomen ( stomach, kidneys, UB, umbilical cord insertion into fetal
abdomen, umbilical cord vessel number)
• Skeletal
• Extremities
• Placneta
• Amniotic fluid
• adnexae

14. HEAD
• Axial plane at lateral ventricle , at BPD
level and posterior fossa level
• Lateral ventricle is measured at level of
atrium (*)
• It should ≤10 mm anytime in gestation ( if
not ventriculomegaly)
• CP= choroid plexus

15. PLANE AT LEVEL OF BPD
• Ventriculomegaly
• Holoproencephaly
• Agenesis of corpus callosum
• Septo-optic dysplasia

16. HEAD ANATOMY
• At the level of posterior fossa
• Landmarks – cerebellum and ciserna magna
and falx
• 3rd and 4th ventricle
• 45ºfrom BPD plane
• Dandy-Walker malformation. Cerebellar
vermis dysgenesis and Chiari II
malformation

17. VENTRICULOMEGALY AT LATERAL
VENTRICLE LEVEL

18. BILATERAL VENTRICULOMEGALY

19. AGENESIS OF CORPUS CALLOSUM
Tear shaped lateral ventricle (*)

20. SEPTO-OPTIC DYSPLASIA
Absence of cavum sptae pellucidi and
Fusion of frontal horns of lateral ventricle (arrows)

21. HOLOPROSENCEPHALY
Single ventricle is seen(*)
Fused thalami ( T)
Note hypoplastic cerebellum ( not typical feature of holo )

22. ANENCEPHALY
Absence fetal cranium and normal brain tissue

23. ENCEPHALOCELES

24. DANDY WALKER MALFORMATION
Absence of cerebellum and
enlargement of cisterna magna ( CM)
and cystic hygroma ( CH)

25. CEREBELLAR VERMIS DYSGENESIS
Cerebellar vermise dysgenesis(CV)
Cisterna magna enlargement (*)

26. CHIARI II
Obliteration of cisterna magna ( CM) and
Abnormal shape of cerebellum

27. SPINA BIFIDA

28. FACIAL ANATOMY
• Plane at level of fetal phase – 90 degree
from BPD plane and tangential view of two
orbits m upper lip and philtrum
• Bi-ocular plane – at the level of orbits
• Outer (1) and inner (2) ocular diameter can
be measured in this plane

29. CLEFT LIP

30. MID SAGITTAL VIEW

31. CHEST ANATOMY
• Chest level of heart
• Four chamber view

32. MAJOR CHEST ANOMALIES
• Ventriclular hypoplasia
• Large septal defect
• Severe out flow tract obstruction
• AVSD -60% of Down syndrome
• Congential cystic adenomatoid malformation (CCAM) extra lobar
sequestration, pleural effusion
• Diaphragmatic hernia

33. PLEURAL EFFUSION

34. CONGENITAL DIAPHRAGMATIC HERNIA
St= stomach
S= spine
R- right
L= left

35. CONGENITAL CYSTIC ADENOMATOID
MALFORMATION
Fetal ascites (*)
Echogenic lung mass ( arrow)
Heart shifted to Rt chest

36. PULMONARY SEQUESTRATION
Pul sequestration( white arrow)
Vascular supply ( yellow arrow)

37. ABDOMINAL ANATOMY
• View in AC measure level
• Non visualization of stomach – sign of esophageal atresia
• Double bubble sign – duodenal atresia
• Omphalocele, gastroschisis
• Kidneys- bilateral renal agenesis ( oligohydramnios)
• Infantile polycystic disease
• Bladder outlet obstruction
• Hydronephrosis ( reflux or pyelo ureteral obstruction – less severe)

38. DUODENAL ATRESIA
Enlarge stomach crosses the midline
Double bubble gas

39. OMPHALOCELE
Central defect

40. GASTROSCHISIS
Lack of membrane cover

41. BILATERAL RENAL AGENESIS
Lack of renal arteries on Doppler
Anhydramnios

42. INFANTILE POLYCYSTIC KIDNEY DISEASE
Increase in echogenicity
Anhydramnios

43. POSTERIOR URETHRAL VALVE
Distended bladder
Dilated ureters
Keyhole appearance of proximal urethra *

44. BILATERAL URETERO-PELVIC
OBSTRUCTION

45. SKELETAL ANATOMY
• Sagittal, transverse and coronal planes
• Recognition of cranial signs ( banana and lemon signs)
• Long bones ( macromelia – severe shortening or bowing)
• Absence of hand or foot
• Aplasia radii
• Fixed joints –suspect the arthrogryposis

46. MID SAGITTAL PLANE WITH INTACT SKIN

47. BANANA SHAPED CEREBELLUM-
ARNOLD –CHIARI
WITH OPEN NEURAL TUBE DEFECT

48. LEMON SHAPED CRANIUM
ARNOLD –CHIARI
WITH OPEN NEURAL TUBE DEFECT

49. LETHAL SKELETAL DYSPLASIA
Small chest in comparison to
Abdomen
Shortening & bowing of long bones

50. THANK YOU
PP BY DOUBLE M
MYANMAR WATER FESTIVAL,16.APR.2019