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Abdominal Ultrasonography
David A. Masneri, DO, FACEP, FAAEM
Assistant Professor of Emergency MedicineAssistant Director, Emergency Medicine Residency
Medical Director, Operational Medicine Division Center for Applied LearningWake Forest University School of Medicine
Disclosure
None:
I do not have any significant financial relationships to disclose.
Outline of Topics:
• Detection of intra-abdominal free fluid and Aorta
• Clinical Application
• Anatomy
• Technique
• Normal US
• Pathologic US
• Pitfalls/Take Home Points
Clinical Application
Question:
Why learn how to identify intra-abdominal free fluid?
Answer:
Clinically significant – Trauma patient assessment
– Part of US evaluation of a hypotensive patient• Component of RUSH Exam
– Ascites assessment
– Assist in US Guided Paracentesis
How good is US for detection of free fluid?
• Detection of Intraperitoneal fluid - Excellent
• Increased sensitivity with – Increasing number of views– Positioning (Trendelenburg) – Serial examinations
• Important to visualize as much of the areas as possible and not just obtain one quick view– Multiple windows may be required to fully evaluate for
free fluid
US is POOR for assessing:
• Solid organ disruption without significant bleed
• Hollow viscus injury
• Retroperitoneal injury or hemorrhage
Appearance of Free Fluid
• Anechoic collections
– Free flowing blood
– Urine, bile, ascites, peritoneal dialysate
• Echogenic
– Clotted blood
– Bowel contents
Peritoneal Windows - Dependent Spaces
• LUQ: Perisplenic space
• RUQ: Morison’s pouch
• Pelvic:– Retrovesical space
– Retrouterine space
1
2
6
34 5
7 7
liver
RUQ (Hepatorenal) View
• Mid-axillary line in 10, 11 interspaces
• Must see junction of right kidney and liver – “Morison's pouch”
• Visualize subdiaphragmatic space
• Visualize the pleural space
8
RUQ View
• Liver cephalad
• Kidney inferiorly
• Morison’s Pouch *
*
**
Normal
Morison’s Pouch
Free fluid in
Morison’s
Pouch
Positive RUQ
Pelvic (Suprapubic or Bladder) View
• Probe should be placed in the suprapubic position
• Full bladder is window
– Helpful to image before placement of a Foley
• Trick of trade:
– If bladder is empty or Foley already placed:
– IV bag on abdomen
– Scan through bag
Pelvic View
• Where to look?– Behind bladder in men
• Retrovesicular space
– Behind uterus in women
• Retrouterine space
• Reduce far gain
• Sagittal and transverse
7
Sagittal Pelvic View
Positive Sagittal Pelvic View
Transverse Pelvic View
Positive Pelvis Transverse View
LUQ (Perisplenic) View
• Probe at left posterior axillary line at Left 8th or 9th Intercostal space
• Angle probe obliquely (avoid ribs)
• Spleen is a smaller window
• Close attention to perisplenic area:– Diaphragm – spleen interface
– Splenorenal space not as important
Normal LUQ
spleen
kidney
diaphragm
Positive LUQ View
Assessment for Intra-peritoneal Free Fluid
Interpretation:
– Exam positive
• If any one abd view positive
– Exam negative
• All three abd views negative
– Indeterminate
• Cannot adequately visualize any one view– Window not available
– Technically limited study
– Body habitus
OK the FAST is positive, but home much fluid is in the belly?
• 1cm stripe 1 L of fluid
• 0.5 cm stripe 500 mL
• Thin stripe 250 mL
Aorta Ultrasound Clinical Application
Question:
Why learn Aorta Ultrasound?
Answer:
Clinically significant in assessing or AAA
– Flank or back pain in the elderly patient
– Part of US evaluation of a hypotensive patient
• Component of RUSH Exam
– Good screening study
Aorta Ultrasound
• Excellent sensitivity for presence of AAA
• High degree of accuracy with brief training
• Improve time to diagnosis and OR vs. CT
• Poorly identifies retroperitoneal rupture
Aorta - Anatomy
• Courses from Xyphoid to umbilicus
• Originates at diaphragm and extends to iliacs
• Main branches– Celiac (CA)– Superior Mesenteric
(SMA) – Renal (RA)– Inferior Mesenteric (IMA)
From: Gray, H. Anatomy of the Human Body 20th ed. 2000
Aorta - Anatomy
• Maximal diameter– Proximal:
• 2.1 cm for males, 1.8 cm for females > 55 yrs
– Distal: • 1.5 cm
• Aneurysm considered when diameter 3 cm– Measure diameter from outer surface of walls
Aorta Technique
• Curved or phased array probe
• Supine position preferred
Aorta Technique
Transverse Aorta
• Anterior to vertebral body
• Ao vs IVC:
– Aorta on pt’s left
– IVC on pt’s right
IVC Aorta
Abd wall
Back
Right Left
Normal Appearance - Transverse
• Vertebral body posterior,– Hyperechoic arch
• Aorta and IVC anechoic circles anterior to vertebral body
• Aorta “divides” at bifurcation
IVC Aorta
Abd wall
Back
Right Left
Bifurcation- Transverse
Aorta Technique
Longitudinal images
• Rotate probe 90°
• Rock and slide technique
Abd Wall
Head Feet
Back
Normal Appearance - Longitudinal
• Longitudinal Aorta – Courses left to right
• Branches– Celiac
– Superior Mesenteric
– Course anterior to Ao
Abd Wall
Head Feet
Back
SMACA
Ao
Technically Difficult Studies
• Bowel gas and obesity may obscure images
• Maneuvers:
–Gentle pressure with probe
– Left lateral decubitus position
–Coronal plane images from right flank
Coronal
Right
Head Feet
Left
Aorta
Cava
IVC Aorta
• On patient’s right
• Undulating motion
• Thin walled
• Compressible
• Collapses with negative intrathoracic pressure– “Sniff”, Valsalva
• On patient’s left
• Pulsatile motion
• Thick walled
• Non-compressible
• Non-collapsing
Color Doppler to Differentiate
AAA
• Best visualized in transverse view– Many AAAs have greater transverse than AP diameters– If you see the aorta VERY WELL it is probably a AAA
• Fusiform– Symmetric, concentric dilatation– More common
• Saccular– Localized out-pouching
• 90 % occur at and below level of renals (region of SMA)– MUST visualize Ao bifurcation for complete scan
AAA – Transverse View Fusiform
Abd wall
Back
LeftRight
AAA - Longitudinal View Fusiform
Abd Wall
Head Feet
Back
AAA – Transverse View Saccular
AAA - Transverse View with Thrombus
Intro to RUSH Exam
• Rapid Ultrasound for Shock and Hypotension
• Assess the Pipes, Pump, Tank
• “HI MAP”
– Heart
– IVC
– Morison’s Pouch (Abdominal FAST views)
– Aorta
– Pneumothorax
Thank You
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