This document provides an overview of the basic sonographic anatomy of major organs. It discusses the interactions of ultrasound waves with different tissues and scanning techniques for organs like the liver, gallbladder, bile ducts, pancreas, spleen, kidneys, and bladder. Key points include how ultrasound is used to visualize the internal structure of organs, identify important landmarks, and evaluate for any abnormalities. Proper patient preparation and positioning techniques are also covered to optimize image quality.

1. Basic Sonographic Anatomy of
Major Organs
Presented by:
Anish Dhakal (Aryan)
MBBS, Patan Academy of Health Sciences

4. What hapens to ultrasound wave?
1. Transmission (Small difference in acoustic impedance = greater
transmission)
2. Reflection : source for ultrasound image
3. Scattering: mostly occurs with RBCs
4. Attenuation: resulting in heat production
5. Refraction: can result in double image artifacts due to difference in
acoustic impedence between body tissues

5. • Fluid: most acoustical energy is transmitted
• Gas or bone: most energy reflected back, not enough energy to
define deeper structures
• Hyperechoic
• Hypoechoic/Sonolucent/Anechoic
• Longitudinal & Transverse Plane
• Patient’s head: your left, Patient’s feet: your right
• Anterior is up & Posterior is down

6. Preparation
• Patient preparation:
• Patient should be NPO for at least 8 hours unless there is
possibilities of dehydration
• In that case water should be given
• As the examination proceeds and there is no clinical
contraindication, water should be given especially when
scanning pancreas, lower abdomen and pelvis

7. Preparation
• Patient position:
• Supine
• Pillow under head
• If much tenderness one pillow should be under the knee
• Choice of transducer:
• For adult 3.5 MHz
• For children and thin adults 5 MHz

8. Scanning technique
• Apply coupling agent
• Start by placing the probe centrally at the top of the abdomen (at
xiphoid angle)
• Slowly move the transducer from the midline across the abdomen to
the right, stopping to check the image approximately every 1 cm.
• Repeat at different level
• Examine the left side in the same way when right side is completed.
• Ask the patient to take deep breath and hold it.

10. Liver scan
• Normal liver:
• Liver parenchyma appears homogenous, interrupted by portal vein
and its branches
• Portal vein and its branches appears tubular structure with
reflecting walls (bright)
• The thinner hepatic veins are non-reflective
• It is possible to follow hepatic veins to their confluence with the
inferior venacava
• Hepatic veins can be made dilated by Valsalva maneuver

11. Scanning technique for liver:

12. Oblique (upper) and transverse (lower) scans of the liver showing portal vein and inferior
venacava

13. Transverse scan: fissure of ligamentum teres hepatis
(falciform ligament)

14. • Right and left lobes of lever can be recognized by identifying
the falciform ligament fissure
• Caudate lobe is recognized by identifying the inferior
venacava.
• Caudate lobe is limited posteriorly by inferior venacava and
separate antero-superiorly from the left lobe by a highly
reflective line.
• Caudate lobe must be identified because it may be mistaken
for a mass.

16. • The normal echogenicity of liver parenchyma is mid way between
pancreas (more echogenic) and spleen (less echogenic)

17. Gall bladder and biliary tree scanning
technique
• Start with longitudinal scan, then transverse scan and
intercostal scan if necessary
• Then turn the patient on the left and make oblique scans at
different angles
• If there is excess bowel gas, examine the patient standing
erect.
• Hand knee position can be used to demonstrate gallstone
more clearly allows the stones to move more anteriorly.

20. Normal anatomy of gall bladder
• On longitudinal scan, it appears echo free, pear shaped structure.
• It is very variable in shape, size, position but normal gall bladder is
seldom more than 4 cm wide.
Longitudinal scan

21. • The thickness of gall bladder wall can be measured by transverse scan
• In a fasting patient, it is 3 mm
• Distended gall bladder has 1 mm thickness
Transverse section: Full gallbladder (wall thickness 1mm)

22. Longitudinal (upper) and transverse (lower) scans of a contracted gallbladder (wall
thickness less than 3 mm)

24. Non-visualization of gallbladder
• The patient has not been fasting: re-examine after an
interval of at least 6 hours without food and drink
• The gall bladder lies in an unusual positions:
• Scan low down in the right abdomen, even as low as the
pelvis
• Scan to the left of the midline and in the patient in the
oblique position with the right side down
• Scan high under the costal margin

25. Non-visualization of gallbladder
• The gallbladder is congenitally hypoplastic or absent
• It is shrunken and full of stones with associated acoustic
shadowing
• It has been removed surgically: examine the abdomen for
scars and ask the relatives
• The examiner is not properly trained or experienced: ask the
colleague to examine the patient

26. Biliary ducts
• It is not always easy to identify the normal main left and
right hepatic bilary ducts, but when visible they are within
the liver and appear as thin walled tubular structure
• Common hepatic duct can be recognized just anterior and
lateral to the crossing portal vein.
• Its cross-section at this point should not be more than 5 mm
• The diameter of common bile duct is variable but should not
exceed 9 mm near its entrant into pancreas

27. Oblique scan: normal common bile duct
Transverse scan: normal common bile duct at porta hepatis

28. Oblique scan: normal common bile duct at porta hepatis

30. Pancreas scan
• Pancreas can be very difficult to find out especially the tail
• Start with transverse scan across the abdomen moving downwards towards
the feet until the splenic vein is seen.
• Splenic vein is seen as a linear, tubular structure with the medial end
broadened.
• This is where it is joined by superior mesenteric vein at the level of the
neck of the pancreas
• The superior mesenteric artery will be seen in cross section just below the
vein.
• By angling and rocking the transducer, the head and tail of the pancreas
can be seen

31. Scanning Technique:

32. If bowel gas obscures the image:

33. Transverse scan: splenic vein, superior mesenteric artery
and body of pancreas seen

34. • Continue transverse scan downward to visualize the head of the
pancreas and uncinated process between the inferior venacava and
portal vein
Transverse scan: head of the normal pancreas scanned
through the left lobe of the liver

35. Transverse scan: tail of the normal pancreas
Transverse scan: Normal pancreatic duct

36. Longitudinal scanning of the pancreas
• Start just to the right of the midline and identify the tubular pattern
of the inferior vena cava with the head of the pancreas anteriorly,
below the liver
• The vena cava should not be compressed or flattened by normal
pancreas.
Longitudinal scan:
Inferior vena cava and
head of the pancreas

37. • Continue longitudinal scan moving to the left
• Identify the aorta and superior mesenteric artery
• This will help identifying body of pancreas
Longitudinal scan: The aorta and body of pancreas

38. Normal pancreas
• Pancreas has about the same echogenicity as the adjacent
liver and should appear homogenous.
• However, the pancreas echogenicity increases with age
• The outline of normal pancreas is smooth.

39. Essential landmarks while scanning pancreas
• Aorta
• Inferior vena cava
• Superior mesenteric artery
• Splenic vein
• Superior mesenteric vein
• Wall of the stomach
• Common bile duct
Note: The most essential land marks are superior mesenteric artery and
splenic vein

40. • The average diameter of head of the pancreas is 2.8 cm
• The average diameter of medial part of the body of pancreas
is less than 2 cm
• The average diameter of tail of the pancreas is 2 cm
• The diameter of pancreatic duct should not exceed 2 mm. it
is normally smooth and wall and lumen can be identified
• The accessory pancreatic duct is seldom visualized.

41. Spleen scan Technique:
• Scan with the patient in the supine position and then oblique position

42. • Scan from below the costal margin, aligning the beam towards the
diaphragm, then in the 9th intercostal space downwards.
• Repeat through all intercostal spaces, first with the patient supine and
then with the patient lying obliquely (30 degree) on right side.

43. • Also perform longitudinal scans from anterior to posterior axillary
lines and transverse upper abdominal scans.
• Scan the liver also, particularly when spleen is enlarged

44. Normal spleen
It is important to identify:
• Left hemi-diaphragm
• Splenic hilus
• Splenic vein and relationship to pancreas
• Left kidney and renal-splenic relationship
• Left edge of liver
• Pancreas

45. • When spleen is normal size , it is difficult to image completely
• The splenic hilus is the reference point to ensure correct identification
of the spleen
• Identify the spleen as the entry point of splenic vessels
Oblique scan: normal spleen and left kidney

46. Echo pattern of spleen
• The spleen should show a uniform pattern of homogenous
echogenicity
• It is slightly less echogenic than lever

47. Common errors in scanning the spleen

48. • Full bladder is required
• Scanning is always done in
deep suspended
inspiration
• Start with the longitudinal
scan over the right upper
abdomen and then follow
with the transverse scan to
visualize the right kidney in
the coronal view
Kidney and ureter scanning

49. • If the left kidney is not visualized generally with bowel gas, try to
visualize in the right decubitus position
• Bowel gas can also be displaced by drinking 3-4 glasses of water

50. Normal kidneys
In newborns, the kidneys are about 4 cm long and

51. Longitudinal scan of normal right kidney

52. Longitudinal scan of normal right kidney with bifid renal sinus

53. Anterior transverse scan through the right renal sinus showing pelvis

55. Longitudinal scan of normal left kidney

56. Transverse scan of normal left kidney

57. Transverse scan of a normal renal sinus (renal pelvis, fat and vessels)

59. Bladder: Scanning Technique

62. Thank you