Abdominal Ultrasonography David A. Masneri, DO, FACEP, FAAEM Assistant Professor of Emergency Medicine Assistant Director, Emergency Medicine Residency Medical Director, Operational Medicine Division Center for Applied Learning Wake 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 liver 2 RUQ: Morison s pouch 3 1 4 5 6 Pelvic: Retrovesical space Retrouterine space 7 7
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 * * * *
Free fluid in Morison s Pouch Normal 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 8 th or 9 th 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 diaphragm spleen kidney
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 20 th 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 Abd wall Ao vs IVC: Aorta on pt s left IVC on pt s right Right Left IVC Aorta Back
Normal Appearance - Transverse Vertebral body posterior, Hyperechoic arch Aorta and IVC anechoic circles anterior to vertebral body Aorta divides at bifurcation Right IVC Abd wall Aorta Left Back
Bifurcation- Transverse
Aorta Technique Longitudinal images Abd Wall Rotate probe 90 Head Feet Rock and slide technique Back
Normal Appearance - Longitudinal Longitudinal Aorta Courses left to right Branches Celiac Superior Mesenteric Course anterior to Ao Head CA Abd Wall Ao SMA Feet Back
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 Cava Aorta Left
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 Right Left Back
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