Ultrasound
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Ultrasound

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  • ???Better at End of talk regarding Pitfalls????
  • Nl layering on L, clumped on R

Ultrasound Ultrasound Presentation Transcript

  • Hepatobiliary Ultrasound Introduction to Emergency Ultrasound
  • Goals
    • Why ultrasound?
    • Anatomy
    • Technique
    • Cholelithiasis
    • Cholecysitis
    • Pearls and Pitfalls
  • Why ultrasound?
    • Hepatobiliary imaging modalities:
      • Ultrasound
      • CT
      • HIDA
      • MRI
      • ERCP
    • Benefits of Ultrasound
      • Performed at bedside
      • Fast information within 5-10 minutes
      • No radiation, No contrast, Low cost
      • Sensitivity 94% with specificity 78%
            • -Shea Arch Int Med 1994
  • Why ultrasound?
    • Evaluation for:
      • Cholelithiasis
      • Cholecystitis
      • Choledocholithiasis
      • Jaundice
    • 1242 patients over 3 years receiving RUQ US
      • 753 from EPs
      • 489 from radiology
    • Average decrease in LOS 22 minutes if received EP US
    • After hours LOS decreased by 1:13 in EP US group
    Academic Emergency Medicine 1999
  • RUQ Anatomy
    • Gallbladder:
    • Posterior to Liver
    • (acoustic window)
    • Right of the Portal Vein
    • Anterior to Duodenum
    • (Beware of Fake-outs)
  • GB Variable Location
    • Scan entire RUQ
      • Midline to Mid-axillary line
    • Always Right of Falciform Ligament
    • Usually Right of Portal Vein
  • GB US Anatomy
    • Gallbladder
      • 7-8 cm long
      • 2-3 cm diameter
        • Max normal <4 cm
    • GB wall
      • <2mm (97% cases)
      • Three layers
        • Outer – reflective
        • Muscular – anechoic
        • Inner – reflective
      • Measure -transverse view
  • GB US anatomy - vascular
    • Distinguishing Hepatic Veins from Portal Veins
    • Hepatic Veins
      • -Thin Walled
      • -Converge into IVC
    • Portal Veins
    • -Echogenic Walls
    • -Branch from Portal Vein
  • Technique
    • Liver is sonographic window
    • NPO (yeah, right)
    • Probe - curvilinear 2-5 MHz
    • Patient positioning
      • Supine
        • Subcostal
        • Deep inspiration and hold
          • Diaphragm pushes liver and gallbladder down
      • Left lateral decubitus
        • Allows GB drop down
      • Intercostal oblique
        • Liver window thru ribs
  • Technique
    • Scan
      • Orientation marker toward head in midline
      • Scan laterally under R costal margin
      • Expect to see gallbladder around midclavicular line
      • Rotate probe to transform image of GB into long axis view
      • Confirm that it is GB by it's &quot;pointing&quot; to R portal vein along main lobar fissure
  • Technique Main Lobar Fissure between gallbladder and right portal vein
  • Technique
    • Two perpendicular views, fanning through gallbladder
      • Longitudinal
      • Transverse
        • 90 o counterclock to longitudinal, fundus to neck
    • Real time scanning
      • Through the entire organ
  • Technique
    • Measurements
      • GB wall thickness
        • anteriorly
      • GB diameter
      • Common bile duct
    4
  • Anatomy Consideration
    • Note gallbladder’s proximity to duodenum
      • Frequent error of novice
  • Anatomy Consideration
    • Normal Folds
      • Crisp folds are normal
      • Hartman's pouch
        • folded neck
      • Apical fold 3%
        • “ Phrygian cap”
      • Septations in neck
        • “ valves of Heister”
  • GB – Imaging Pitfalls
    • Misidentifying duodenum for GB
    • Unusual anatomic location
    • Contracted after eating
      • Smaller thereby harder to find
      • Contracted GB has thicker walls
        • Walls still <4mm
    • Missing the gallbladder neck
    • Bowel gas interfering with imaging
  • Porta Hepatis
    • Portal Triad
    • Hepatic Artery
    • Common Bile Duct
    • Portal Vein
  • CBD US Anatomy
    • <4mm (98% cases)
      • Inner wall to inner wall
          • Bachar JUM 2005
    • Can increase by 1mm/10 yrs age.
    • >10 mm =
      • Likely obstruction
  • Landmark methods for finding CBD
    • Portal Vein - Extrahepatic
      • Runs longitudinally
      • Towards pt’s right shoulder
      • 11 O’clock
      • Rotate to 8 O’clock
  • Porta Hepatis
    • Mickey Mouse Sign
    • Right Ear – Common Bile Duct
    • Left Ear – Hepatic Artery
    • Face – Portal Vein
  • Landmark methods for finding CBD
    • Find “Confluence”
      • Splenic vein joins the SMV to become Portal Vein
      • Probe located in Epigastric - TRV
  • Porta Hepatis - Pitfalls
    • Misidentification of right portal vein as the Common Portal Vein
    • Porta Hepatis off axis
    • Inability to use liver window
        • Left lateral decubitus
        • Have patient take deep breath and hold
          • Brings down liver to use as window
        • Intercostal view
          • Intercostal views take practice and patience
  • Cholelithiasis
  • U/S Gallstone Findings
    • Strongly Echogenic
    • Posterior Acoustic Shadowing
      • “ Clean” shadowing
    • Mobile
      • Move with change in patient position
    • Convenience sample of 109 ED patients undergoing RUQ ultrasound by radiology had EP RUQ US performed
    • 49/51 patients had their gallstones detected on EP RUQ US (96% [87-99])
    • 51/58 pts without gallstones correctly identified by EP RUQ US (88% [77-95])
    Journal of Emergency Medicine 2001
  • Cholelithiasis
  • Cholelithiasis
  • Cholelithiasis
  • Cholelithiasis
  • Cholelithiasis
  • Cholelithiasis - WES sign
  • Sludge
    • Sludge is precursor of stones
      • significance depends clinically
      • including other US findings
          • Ohara 1990, Lee 1988
    • Bizarre echogenic “lava-lamp” shapes
      • Change with movement => flows
    • Can resemble tumor
    • “ pseudosludge” artifact
      • beam width /side lobe artifacts
        • do not layer out with gravity
        • extend beyond walls of GB
        • inconsistent between views
  • Various Stages of Sludge Normal layering Clumpped 29559978 RUQ sludge filled GB29559978_2.2.2005.18.37.5_5.avi
  • Sludge versus Stones
    • Sludge
    • Continuum
    • Crystallized Bile Salts
    • Allow passage of ultrasound waves
    • No shadowing seen
    • Stones
    • End of the continuum
    • Density prevents passage of ultrasound
    • “ Clean” shadowing
  • Cholecystitis
  • Cholecystitis
    • Signs and symptoms
      • RUQ abdominal pain
      • Murphy’s sign
      • Fever/ Chills
      • Leukocytosis
      • Jaundice (choledocolithiasis)
    Later finding
  • Pathophysiology
    • Obstruction
    • Aseptic Inflammation
    • Wall Edema
    • Infection
  • Cholecystitis: US Findings
    • Gallstones
    • Sonographic Murphy’s
    • GB wall edema
      • Especially Focal
    • GB wall thickening
    • Increased Transverse
      • GB diameter
    • Pericholecystic fluid
  • Sonographic Murphy’s sign
    • Find gallbladder and press on it.
    • Sensitivity 60 – 95%
    • Specificity 90 – 95%.
      • Ralls 1985, Ralls 1982, Simeone 1988
    • 92% PPV SonoMurphy+stones
    • Morphine does not interfere with exam
          • -Nelson JEM v28, 2005
    • Sonographic Murphy's by EP
      • Sensitivity = 75%
      • Specificity = 55%
      • Positive predictive value = 17%
      • Negative predictive value = 95%
    Journal of Emergency Medicine 2001
  • Wall Thickness
    • Normal Abnormal
    • Usual thickness – 2mm (4mm upper limit normal)
    • In the clinical setting of acute cholecystitis about 90 - 100% specific, 50 - 70% sensitive
            • Finberg 1979, Birnholz 1981
    • Thickened walls can be due to medical disease ie anasarca
  • Wall thickness
    • Note the edema separating the walls
  • Other causes of thickened walls
    • 55 consecutive patients w/ thick walls
      • one third due to biliary disease
      • out of 28 with medical etiologies:
        • 19 due to hypoproteinemic states
        • 9 due to CHF, 6 due to liver disease, 4 due to CRF
        • 3 due to pancreatitis
          • Coh an 1987
    • Also associated w/ AIDS and ascites
  • Increased Transverse Diameter
    • > 4-5 cm diameter
      • Sens 84.4%
          • Weedle 1986
    • Dependent on degree of inflammatory process
  • Pericholecystic Fluid
    • Seeping inflammatory fluid
      • Gallbladder
      • Liver
    • Consider Perforation
  • Choledocolithiasis
    • View Portal Triad
      • Common bile duct
        • Avg size 4 mm
        • Incr 1mm/ 10 yrs
        • Up to 10 mm post cholecystectomy
        • >10 mm -> Obstruction
  • Choledocolithiasis
    • Allow 1 mm for each decade to max 8.5mm
            • -Bachar JUM 22, 2003
    • CBD increased after cholecystectomy, with age and weight
            • Wu 1984
    • In acute obstruction
      • extrahepatic ducts dilate in > 24 hours
      • intrahepatic ducts 1 to 2 days later
  • Intrahepatic Cholestasis -Too many tubes -best seen in transverse L liver
  • Liver Masses
    • Check echodensity for homogeneity
      • Heterogeneous - consider masses vs edema
  • Liver Masses
  • Pitfalls – Bowel Gas
    • Proximity to colon
      • Hepatic flexure
      • Gas artifact
        • Impossible to state stones.
  • And so remember
    • Real time dynamic scanning
    • Gallbladder
      • 4mm (GB wall)
      • 4cm (GB diameter)
    • CBD
      • Usually <4mm
      • <10 mm max in elderly patient
    • Gallstones always make clean shadows
    • Sludge resembles “lava lamp” layering
    • Check the neck for hidden stones
  • Tips for improving view
    • Supine view with patient holding deep breath to move liver down
    • Intercostal oblique at anterior axillary line
    • Still can't find the gallbladder?
        • Transverse view of upper pole R kidney, then look medial for GB
        • Coronal view of Morison's pouch, then fan 20 degrees anteriorly for GB
  • Pitfalls
    • Bowel gas obscuring the gallbladder
    • Failure to thoroughly scan the neck of the gallbladder
    • Mistaking the duodenum for the GB