Gallbladder Ultrasound

See Also

Efficacy
Cholelithiasis

Test Sensitivity for Gallstones: 95%
Test Specificity high
Can visualize Gallstones >= 2 mm
Serial Ultrasound in 12-16 hours may demonstrate progression
1. Increased gallbladder wall thickening
2. Ultrasonic murphy's sign

Evaluation
Cholecystitis

Findings suggestive of Cholecystitis
1. Presence of Gallstones
2. Thickened gallbladder wall
3. Gallbladder distension
4. Pericholecystic fluid
5. Positive sonographic Murphy Sign (pain provoked when pressure applied directly to visualized gallbladder)
Interpretation: Above findings present
1. Cholecystitis Positive Predictive Value (PPV) 90%
Interpretation: Above findings absent
1. Cholecystitis unlikely

Imaging
Point of Care Ultrasound

Positioning
1. Patient starts supine
  1. May need to switch to left lateral decubitus or upright in difficult cases
2. Images may improve (decrease rib shadowing) with a held deep inspiration
3. Patients should not have eaten recently
  1. Gallbladder will contract after eating making visualization very difficult
Transducer
1. Curvilinear transducer (large footprint abdominal probe, 2.5 to 5.0 MHz)
  1. Typical probe with best penetration and best visualizes common bile duct
2. Phased-array probe (cardiac probe)
  1. Indicated if only view is lateral intercostal (due to overlying gas, patient position)
  2. See Right Intercostal Oblique Ultrasound View (part of FAST Exam)
Precautions
1. Scan gallbladder in both axes (short and long axis)
  1. Scan through a series of planes (serial cuts) in each axis
2. Gallstones
  1. Visualize suspected Gallstone movement in various patient positions (decubitus, supine, prone)
  2. Carefully evaluate gallbladder neck (easily missed Gallstones, especially while supine)
Landmarks: Long Axis (longitudinal)
1. Portal triad
  1. Appears as Mickey Mouse (Portal Vein as face, and CBD and HA as each of the ears)
  2. Anterior: Common bile duct (CBD) and hepatic artery (HA)
    1. Consider using color doppler (at low threshold) to distinguish hepatic artery and common bile duct
    2. Do not need to distinguish CBD from HA if both are small
  3. Posterior: Portal Vein
  4. Inferior Vena Cava lies deep to portal triad
2. Gallbladder is medial to the portal triad
  1. Consider following the Portal Vein medially to identify the gallbladder
  2. Then rotate the probe obliquely to position the gallbladder in long axis
Landmarks: Short Axis (transverse)
1. Common bile duct (faint narrow line normally) in long axis
2. Portal Vein (immediately below common bile duct) in long axis
3. Inferior vena cava (~1 cm inferior to Portal Vein) in cross-section
Images
1. RUQ/GB Long Axis
2. RUQ/GB Long Axis - Intercostal
3. RUQ/GB Short Axis
Gallbladder localization
1. Anterior Long axis or longitudinal approach
  1. Start with probe indicator at 12:00 with energy directed towards patient's right Shoulder
  2. Sweep from midline to right lateral Abdomen immediately below right costal margin
2. Anterior Short axis or transverse approach
  1. Start with probe indicator at 9:00 with energy directed towards patient's right Shoulder
  2. Gradually tilt probe through an arch from head to foot
3. Lateral Long axis or longitudinal approach
  1. Start at lateral oblique at Morrison's Pouch (as in FAST Exam)
    1. See Right Intercostal Oblique Ultrasound View
  2. Slide probe anteriorly until Gall Bladder is visualized
  3. May require patient to take a deep breath to bring Gall Bladder below the level of rib shadowing
Measurements
1. Gallbladder anterior wall thickness
  1. Measure at crisp interface between liver and gallbladder, at mid-anterior wall (not at neck/fundus)
2. Common Bile duct
  1. Measure in the bile duct's long axis where it lies above the Portal Vein
  2. Obstructed, dilated common bile duct will approach the size of the Portal Vein
Cholecystitis findings
1. Common bile duct >8 mm diameter is considered dilated
  1. Borderline common bile duct diameter: 6-8 mm
  2. Post-op Cholecystectomy common bile duct diameter is normal up to 10 mm
2. Gallbladder wall is thick (>3 mm) and echogenic
3. Ultrasound Murphy's Sign (compression of gallbladder with probe increases pain)
4. Pericholecystic fluid
Cholelithiasis (Gallstone) findings
1. Gallstones are echogenic and when >3mm result in shadowing
2. Gallstones are mobile and will move when patient changes position (contrast with immobile polyps)
3. Gallstone in the gallbladder neck (especially if immobile) predicts impending Cholecystitis within ensuing days
Normal findings
1. Gallbladder sludge is a common finding when oral intake is decreased

Resources

Gallbladder Ultrasound Video (Part 1, Dr. Perera, SonoSite)
1. http://www.youtube.com/watch?v=FY3dBuQV03w
Gallbladder Ultrasound Video (Part 2, Dr. Perera, SonoSite)
1. http://www.youtube.com/watch?v=L3e-YdQRa-A
Gallbladder Ultrasound Video (Part 3, Dr. Perera, SonoSite)
1. http://www.youtube.com/watch?v=Xsj5j2hzjtA

References

Mateer and Jorgensen (2012) Introduction and Advanced Emergency Medicine Ultrasound Conference, GulfCoast Ultrasound, St. Pete's Beach
Noble (2011) Emergency and Critical Care Ultrasound, Cambridge University Press, New York, p. 151-71
Reardon (2016) Gallbladder Ultrasound, Stabroom.com online video, accessed 4/1/2016
Reardon (2011) Pocket Atlas Emergency Ultrasound, McGraw Hill, New York, p. 129-61
Reardon (2013) Emergency Ultrasound Course, 3rd Rock Ultrasound, Minneapolis, MN