1. Emergency Ultrasound Mary Ann Edens, M.D.
Assistant Professor, Dept. of EM
Director of Emergency Ultrasound

2. Physics
Sound waves with frequencies greater than 20 kHz are called ultrasound
Medical ultrasound waves have frequencies between 1 – 20 MHz
Sound waves are mechanical waves
Created in the transducer by back and forth displacement

3. Physics and Knobology

4. Physics
Ultrasound transducers send out sound waves and then “listen” for returning echoes
Most transducers at this time send out waves only approximately 1% of the time

5. Physics
Acoustic impedance determines the amount of sound waves transmitted and reflected by tissues
Reflection occurs when the ultrasound beam hits two tissues (areas) having different acoustic impedance
Large differences in impedances inhibit useful information

7. Terms Hyperechoic Structure reflects most sound waves
Structure appears white on screen

10. Terms Anechoic Structure allows most sound waves through
Structure appears black on screen

14. Terms Echogenic Tissues in between
Allow some sound waves through and reflect others
Structures appear in various shades of gray depending on amount of reflection

17. Terms
Homogeneous
Tissue has uniform texture

18. Terms
Heterogeneous
Various degrees of echogenicity present

19. Terms
Isoechoic
Two tissues with same amt of echogenicity

20. Transducers The higher the frequency, the better the resolution
The better the resolution, the better you can distinguish objects from each other

21. Transducers
Lower frequency

22. Transducers
Higher frequency

23. Transducers Linear Gives rectangular image
Generally has higher frequency
Good for looking at a smaller area and for gauging depth
Gives more of a one dimensional view
Sometimes referred to as the vascular probe

24. Transducers
Linear

25. From Heller & Jehle. Ultrasound in Emergency Medicine. Philadelphia:
W.B. Saunders, 1995, p. 202.

26. Transducers Curvilinear
Uses same linear orientation but arranged on a curved surface
Generally lower frequency
Gives a wider angle of view

27. Transducers
Curvilinear

30. Transducers
The footprint refers to the portion of the transducer that contacts the patient
Curvilinear transducers come with different footprints for different purposes

31. Transducers
Transducers have a marker that corresponds to a mark on the screen
Helps with spatial orientation

33. Knobology Power Controls the strength or intensity of the sound wave
Use ALARA principle
As low as reasonably acheivable

34. Knobology Gain Degree of amplification of the returning sound
Increasing the gain, increases the strength of the returning echoes and results in a lighter image
Decreasing the gain, does the opposite

35. Knobology
Too much gain

36. Knobology
Too little gain

37. Knobology
Optimal gain

38. Knobology Time gain compensation
Used to equalize the stronger echoes in the near field with the weaker echoes in the far field
Should be a gentle curve

39. Knobology Focal zone Where the narrowest portion of the beam is
Gives the optimal resolution

40. Knobology
Focal zone off
Focal zone right

41. Knobology Depth Each frequency has a range of depth of penetration
Decrease the depth to visualize superficial structures
May need to increase the depth of penetration to visualize larger organs

42. Knobology
Zoom
Can place zoom box on a portion of a frozen image to enlarge that portion of the image
May lose some resolution because pixels are enlarged

43. Basic OB/Gyn Ultrasound

44. Goals
To perform a focused examination on patients with complicated first trimester pregnancies
To rule in an intrauterine pregnancy (not to rule out an ectopic)

45. Scanning Techniques Transabdominal Supine position
A full bladder will provide sonographic window
3.5 MHz curvilinear transducer
Place transducer in the sagittal plane just above the pubic bone

47. Scanning Techniques Transabdominal
Locate the long-axis of uterus and sweep from side to side
Turn transducer 90 degrees counter-clockwise

49. Scanning Techniques Transabdominal
Locate the short-axis of the uterus and angle cephalad and caudad
Goal is to see the entire uterus

50. Scanning Techniques Transvaginal Supine lithotomy position
MHz intracavitary transducer
Need to apply gel to the transducer and transducer cover
Have assistant to chaperone

51. Scanning Techniques Transvaginal
With locator anterior, scan the long-axis of the uterus
Transducer does not need to be inserted all the way to the cervix

53. Scanning Techniques Transvaginal
Turn transducer 90 degrees counter-clockwise to scan the short-axis of the uterus
Goal is to see the entire uterus

55. Sonographic Findings Nonpregnant Uterus
May see endometrial stripe

58. Sonographic Findings Normal Intrauterine Pregnancy
Gestational sac
First indication of pregnancy but not a reliable sign of an IUP
Transabdominal scanning
5.5 – 6 weeks gestation
B-HCG of 6500

59. Sonographic Findings Normal Intrauterine Pregnancy
Gestational sac
Transvaginal scanning
4.5 – 5 weeks gestation
B-HCG of

60. Sonographic Findings Normal Intrauterine Pregnancy
Gestational sac
Features of normal sac
Round or oval in shape
Central position in uterus
Smooth contour

62. Sonographic Findings Normal Intrauterine Pregnancy
Yolk sac
First reliable sign of an intrauterine pregnancy
Should be seen by 5 – 6 weeks gestation

64. Sonographic Findings Normal Intrauterine Pregnancy
Fetal pole
Should be seen by TV when mean gestational sac diameter is > 16 mm
Cardiac activity usually detected by TV by 6 weeks gestation
Use M-mode to confirm activity

68. Sonographic Findings Ectopic Pregnancy
Detection of ectopic pregnancy outside uterus < 20%
Suggestive findings
No IUP with high B-HCG
Pseudogestational sac
Complex adnexal mass
Free fluid in cul-de-sac

72. Basic Trauma Ultrasound
The FAST Scan

73. Goals
Bedside screening test for the detection of hemopericardium and hemoperitoneum
Not a formal study to detect pathology

74. Scanning Techniques Four standard views 3.5 MHz curvilinear transducer
Pericardial
Subxiphoid (parasternal if cannot obtain subxiphoid view)
Perihepatic
Perisplenic
Pelvic
3.5 MHz curvilinear transducer

75. Scanning Techniques Pericardial views Subxiphoid view
Place transducer in midline and aim towards the patient’s left shoulder

77. Scanning Techniques Pericardial views Parasternal view
Place transducer oriented between ribs on the patient’s left

79. Scanning Techniques Perihepatic view
Place the transducer on the patient’s right in the midaxillary line between the 8th and 11th intercostal spaces

81. Scanning Techniques Perisplenic view
Place the transducer on the patient’s left in the midaxillary line between the 8th and 11th intercostal spaces

83. Scanning Techniques Pelvic view
Place the transducer in midline just above the pubic symphysis

85. Sonographic Findings Pericardial Views
Subxiphoid view
Four chamber view
The visceral and parietal pericardium are adherent

88. Sonographic Findings Pericardial Views
Subxiphoid view
Pericardial fluid will show as a dark layer in between the visceral and parietal pericardial layers
Tamponade is diagnosed by circumferential fluid collection with diastolic collapse of the right atrium or ventricle

90. Sonographic Findings Perihepatic View
Normal view
The kidney and liver will be adjacent to each other
Morrison’s pouch will not be visible
Morrison’s pouch is the space between the liver and the right kidney

92. Sonographic Findings Perihepatic View
Abnormal view
Intraperitoneal fluid will appear as anechoic area in Morrison’s pouch
Be careful not to misinterpret a fluid filled structure (i.e. gallbladder, colon, duodenum) as free fluid

96. Sonographic Findings Perisplenic View
Normal view
The left kidney and spleen are normally adjacent to each other

99. Sonographic Findings Perisplenic View
Abnormal view
Intraperitoneal fluid will appear as anechoic area in the subphrenic space or splenorenal fossa
Be careful not to misinterpret a fluid filled structure (i.e. stomach, colon) as free fluid

101. Sonographic Findings Pelvic View
In female patients, intraperitoneal fluid will appear in the pouch of Douglas just posterior to the uterus
In male patients, intraperitoneal fluid will appear in the retrovesicular pouch or cephalad to the bladder

103. Interpretation of FAST
Positive pericardial view
Patient should go to the OR
Positive perihepatic, perisplenic or pelvic view
The stable patient should go to CT to further define injuries
The unstable patient should go to the OR

104. Basic Abdominal Ultrasound

105. Gallbladder Goals Evaluation of RUQ abdominal pain for diagnosis of
Cholelithiasis
Cholecystitis

106. Gallbladder Scanning Technique
Supine or left lateral decubitus position
Ideally patient should be NPO for 4-6 hours
MHz curvilinear transducer
Start with transducer in sagittal plane in the midclavicular line at the lower costal margin

108. Gallbladder Scanning Technique
Slide and angle through liver to find gallbladder
Look for main lobar fissure to lead to the gallbladder
Having patient take a deep breath may help
Once gallbladder is visualized, turn transducer slightly to find long-axis of the gallbladder

109. Gallbladder Scanning Technique
Sweep from side to side to evaluate for stones
Turn the transducer 90 degrees counterclockwise to find short-axis of the gallbladder
Angle the transducer to evaluate the entire gallbladder

111. Gallbladder Sonographic Findings
Normal gallbladder
Anechoic
Wall thickness < 3 mm
Transverse diameter < 4 cm
May see folds or valves within the gallbladder

115. Gallbladder Sonographic Findings
Abnormal gallbladder - cholelithiasis
Stones > 3mm in size will cause shadowing
Smaller stones and “sludge” will not
May see wall-echo sign in a gallbladder full of stones
Evaluate neck of gallbladder carefully for an impacted stone

120. Gallbladder Sonographic Findings
Abnormal gallbladder - cholecystitis
Wall thickening > 3 mm
Gallbladder enlargement
Pericholecystic fluid
Sonographic Murphy’s sign
Pressing with transducer directly over the gallbladder elicits pain

123. Renal Goals
Detection of obstructive uropathy (i.e. hydronephrosis) in patients with
Suspected renal colic
Acute renal failure

124. Renal Scanning Techniques
Left lateral decubitus or right lateral decubitus for each respective kidney
3.5–5.0 MHz curvilinear transducer
Use intercostal oblique technique described for the FAST scan
May also use subcostal approach in the sagittal plane at the midclavicular line

127. Renal Scanning Techniques
Once kidney is found turn transducer slightly to find long-axis
Scan through entire kidney
Then turn transducer 90 degrees counterclockwise to find the short-axis

130. Renal Sonographic Findings
Normal kidney
The renal pelvis appears echogenic
The surrounding renal cortex is hypoechoic
The size is ~ 9-13 cm in length

132. Renal Sonographic Findings
Abnormal kidney - hydronephrosis
Appears as anechoic dilatation of the renal pelvis
Marked thinning of the cortex implies long- standing hydronephrosis
The degree of hydronephrosis does not correspond with the degree of obstruction
May be present uni- or bilaterally

136. Renal Sonographic Findings
Abnormal kidney – renal cysts
Appears as anechoic areas within the cortex with a normal renal pelvis

139. Aorta Goals
Evaluation of abdominal or back pain to rule out AAA

140. Aorta Scanning Technique
Supine position
MHz curvilinear transducer
Start with transducer in sagittal plane in the midline just below the xiphoid process
Angle the transducer slightly to the patient’s left to locate the aorta

142. Aorta Scanning Technique
Slide and rock the transducer caudally down the abdomen to follow the aorta all the way to the bifurcation
Then move the transducer back to the subxiphoid space and relocate the aorta
Turn the transducer 90 degrees counterclockwise to visualize the short-axis of the aorta (transverse view)

144. Aorta Scanning Technique
Again slide the transducer caudally down the abdomen to follow the aorta all the way to the bifurcation
Any measurements of the aorta should be taken in this transverse view
Pressure may be placed to distinguish the aorta from the IVC
The IVC will collapse, the aorta will not

145. Aorta Sonographic Findings
Normal aorta
Diameter no greater than 3 cm at any point
Be careful not to measure obliquely
Should taper distally
Lumen should appear anechoic

149. Aorta Sonographic Findings
Abnormal aorta - aneurysm
Diameter greater than 3 cm at any point
Be careful not to measure obliquely
Most aneurysms are found infrarenally
Mural thrombus may be seen as areas of low to medium echogenicity within the wall

151. Aorta Sonographic Findings
Abnormal aorta - dissection
Aorta may be greater than 3 cm, but not always
Diagnosed when an intimal flap is visualized within the vessel lumen

152. Ascites Goals Evaluation of the patient with liver failure
May be helpful in deciding the most appropriate needle placement for paracentesis

153. Ascites Scanning Techniques
Same general technique as described with FAST scan

154. Ascites Sonographic Findings
Same general findings as described with FAST scan

155. Basic Cardiac Ultrasound

156. Goals To evaluate the patient with cardiac failure for
Pericardial fluid/tamponade
Cardiac activity

157. Scanning Technique Same general technique as described with FAST scan
Best way to document the presence of cardiac activity is with the M-mode

158. Sonographic Findings Pericardial fluid as described with FAST scan
M-mode shows good movement with normal cardiac activity

160. Sonographic Findings
In cardiac arrest, four-chamber view may be difficult to see
M-mode shows no movement in area of heart

162. Central Line Placement
US can be used for placement
Easiest line to use for is IJ
Place patient in Trendelenberg position if able
Place linear probe on neck

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