Obstetric Ultrasound Workshop

1
Obstetric Ultrasound Workshop
Skeleton and Abdomen

• Suchaya Luewan, MD

2
Sonography of Skeleton

• Embryology
• Appendicular skeleton GA 4 wk
• Pectoral and pelvic girdles
• Extremities
• Axial skeleton
• Vertebraes and ribs ---- GA 4 wk
• Skull ---- GA 5 wk
• Sternum ---- GA 6 wk

3
Ossification
Limb bud
4th wk

• Bone Mesenchymal tissue condensation
• connective tissue
• Chondroossification
• Membranous Cartilageneous

Mesoderm, ectoderm
6th wk
Axial skeleton
Appendicular skeleton
10th wk
4

• Gestational age (wk by LMP)
• 6
• 7
• 8
• 9
• 11
• 12-16
• 5,6 month
• After birth

• Primary Ossification
• Vertebra
• Skull
• Clavicle, mandible
• Maxilla
• Long bone
• Ischium, metacarpals,
• metatarsals
• Pubis, tarlus, calcaneus
• Carpals, tarsals

5
Ossification centers

• Primary ossification center diaphysis
• Secondary ossification center epiphysis

6
Pattern timing

• Identification Ulnar - more proximal extension
  than radius
• Limitation of fetal evaluation distal spine-
  NTD before 17 wks
• Lung maturity, IUGR
• GA gt33 wk - distal femoral epiphyseal
• GA 35 wk - proximal tibial epiphyseal
• GA 38 wk - humeral head

7
A should for Fetal Skeletal Sonography

• Development of ossification canters in the fetal
  vertebral column
• The length of extremity bones
• The presence of the extremity bones
• The mobility and exposure of the extremity
• The normal formation of hand and foot

8
A must for Fetal Skeletal Sonography

• Femur length for GA assessment
• Appropriate plane
• U/S beam should be perpendicular to the bone
• Measurement is made along the femur diaphysis
• Exclude the distal femoral diaphysis

9

• In second trimester
• Mild femoral shortening (lt90 of predicted)
• risk of Trisomy 21 1
• Mild humeral shorting
• risk of Trisomy 21 3
• In third trimester
• FL foot length ratio lt0.9 skeletal dysplasia

10
Upper Extremities
Radius
Humerus
Ulnar
11
Clavicle ,Scapular, Humerus
Radius, Ulna
Proximal end Ulna longer than Radius
12
Lower Extremities
13
Distal femoral epiphyseal
Femur , Tibia, Fibula Tibia Fibula similar in
length
14
Hand

• Carpals - hypoecho, no ossification
• Metacarpals and phalanges 2nd trimester

15
Foot

• GA 22-24 wk Talus and Calcaneous
• 2nd trimester metatarsals and phalanges

16
Ribs / Spine / Pelvis

• Spine
• 3 primary ossification
• 1 Centrum (body)
• Ossified from lower T ? L
• 2 posterior neural arch
• Lamina ossification
• Cervical GA 18-19 wk
• Thoracic GA 20-22 wk
• Lumbar GA 22-24 wk
• Sacral arch GA 25 wk

Rib
17
Appropriate plane for spine sonography
Parallel of posterior element

• Longitudinal saggital plane
• Longitudinal coronal plane
• Cross-sectional plane
• Looking for
• Alignment
• Skin covering
• Abnormal outward faring of the posterior neural
  arch ossification centers

18
Coronal view

• Pelvis
• Ossification
• Iliac early 2nd trimester
• Ischial 4 mo
• Pubic 6 mo

19
Sonography of Abdomen

• GA and growth assessment by AC
• Completion of abdominal wall
• Stomach
• Liver and gall bladder
• Small and large bowel
• Kidney and bladder

20
Embryology

• Primitive gut late GA 5th wk
• Foregut esophagus, stomach, proximal duodenum
• Midgut distal duodenum, jejunum, ileum, colon
• Hindgut colon, rectum, anus, vagina and
  bladder

21
GA and Growth assessment by AC

• Appropriate plane
• Transverse axial image of fetal abdomen at the
  level of liver
• Landmark
• Umbilical portion of the left portal vein deep in
  liver
• Fetal stomach
• Alignment of 3 ossification center of vertebrae

Umbilical portion of LPV
3 Ossification
Stomach
22
Umbilical portion of LPV
3 Ossification
Stomach
23
Sonography of stomach

• Fluid contained organ
• Detect early 9 wk after 14 wk identified each
  parts ( greater/lesser curvature, pylorus)
• Its size depends on swallowed AF volume
• At term 400-500 ml
• 3 Components
• Fundus (posterior)
• Body
• Antrum (anterior)
• Incisura angularis
• notch of variable depth along lesser curvature

24
Sonography of Liver and Gall Bladder

• Visualized in 2nd trimester
• Liver
• Liver calcification (diffuse, branching,
  scattering)
• Space-occupying lesion
• Gall bladder
• oval shape, located in the right to portal
  umbilical vein on transverse view

25
(No Transcript)
26
Sonography of fetal small bowel

• Visualized at GA 12 wk
• Meconium filled small bowel
• echogenic mass like after GA 15-16 wk (fetal
  abdominal pseudomass)
• Fluid-filled loops of small bowel
• Active small bowel peristalsis after GA 26-30 wk

27
Sonography of large bowel
Small bowel

• Visualized after GA 26 wk
• A long tubular hypoechoic structure with
  well-defined walls, located in the flank and
  upper abdomen
• Low level echoes secondary to meconium within
  its lumen
• Not exhibit active peristalsis
• Haustra in GA 30 wk

Large bowel
28
(No Transcript)
29
Sonography of fetal kidney

• Visualized GA 15-16 wk , esp. GA 20 wk
• Longitudinal plane bilateral eplliptical
  sttructure
• Transverse plane circular structure adjacent
  to the lumbar spinal ossification
• Constant ratio of kidney circumference to
  abdominal circumference 0.27-0.30

30
In late pregnancy echopanic fetal renal
pyramids , columns of Bertin in ant post row
31
Fetal adrenal gland

• Larger than adult
• Hypoechoic and large cortex
• Suprarenal location
• Triangle shape gland caps the upper pole of
  kidney

32
(No Transcript)
33
Sonography of fetal bladder

• Early visualized at GA 15 wk
• Re examine bladder at 30-45 mins after
  nonvisualized bladder

34
Sonography of abdominal wall
Diaphragm
Cord insertion
35
Pseudoascites

• Thin rim of lucent tissue along the anterior
  surface of abdominal cavity, beneath skin
• Hypoechoic anterior abdominal musculature

36
Abdominal Pseudomass

• Meconium-filled small bowel
• In 2nd trimester

37
Gastric Pseudomass

• A discrete, intraluminal, echogenic mass
• From swallowed cell and debris before active
  peristalsis developed