Biliary Microlithiasis

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Biliary Microlithiasis - Theories

generalizations based on our limited evaluation

Unselected sequential patients for routine abdominal ultrasound had all gallbladders examined using the rapid patient rotation. Intraluminal gallbladder echogenic foci were demonstrated in 294 out of 3820 patients examined, representing an incidence of 7.7%. The foci appear as discrete, echogenic structures approximately 0.5 to 2mm, which rapidly fall to the dependent gallbladder wall when agitated by rapid patient rotation. They do not shadow and are not seen on the dependent gallbladder wall when the patient is stationary, likely remaining very near or against the wall during slow rotational movements with routine ultrasound. The transducer must be positioned on the gallbladder immediately at the end of a patient rotation because the foci settle to the dependent wall very rapidly and cine loop best records them. 

Our findings suggest of the patients with intraluminal echogenic foci, 72% had intermittent RUQ pain with no known etiology, 11% were referred as idiopathic pancreatitis, 10% had elevated liver enzymes with no known etiology, 6% had no clinical findings of pancreatic, biliary or gallbladder disease. These foci were found in nearly all patients referred as idiopathic pancreatitis and in 50% of patients with elevated liver enzymes of unknown etiology.  A history of intermittent RUQ pain occurred in approximately 50% of patients with elevated liver enzymes without a known etiology and in approximately 50% of patients prior to the onset of clinical pancreatitis.  Foci are seen in patients between 2 to 55 years of age. 60% were female including foci found in pregnancy. History of intermittent RUQ pain was usually up to 1 year with the longest 18 years, occurs daily or infrequently, with eating but more commonly occurs randomly and may wake patients at night. Pain in children tends to be para-umbilical and epigastric. A 14 year old girl had intermittent RUQ with fluctuating elevated liver enzymes. GI specialist said nothing found and it would likely go away.  We advised the GP to use URSO; the GP did it.  The patient is pain free with normal liver enzymes and no foci on repeat rotational ultrasound.

Foci are not seen Routine Gallbladder Ultrasound because:

  1. they blend in with the dependent gallbladder wall, do not shadow, are not see in the resting  
    position and are only seen when falling in bile.
  2. they stay on the dependent wall of the gallbladder with slow rotational movement and are
    not stirred up.
  3. the patient is not rotated fast enough to stir them up.
  4. they settle almost instantly and the transducer must be on the gallbladder immediately after 
    rapid patient rotation stops. 
  5. multiple maneuvers may be required to visualize them.

Potential Studies that might verify the clinical significance of Foci - heavy gallbladder densities (HGD):

  1. HGD correlated with idiopathic, familial, chronic, alcohol, pregnancy pancreatitis.
  2. HGD in patients with ERCP induced pancreatitis either with or without gallstones.
    Determine the incidence of HGD with gallstone pancreatitis compared to the
    incidence of pancreatitis where foci are not found with gallstones.
  3. Long term follow up of asymptomatic and right upper quadrant pain with foci.
  4. HGD associated with undiagnosed elevation of liver enzymes, with or without
  5. HGD found pre cholecystectomy correlated to “the same” pain post cholecystectomy.
  6. Correlate HGD found with acute gallstone cholecystitis and compare to acute
    gallstone cholecystitis without HGD. 
  7. The association of HGD in acalculus cholecystitis.
  8. Determine if RUQ pain is more common when HGD are present with
    gallstones compared to when there are no HGD with gallstones. 
  9. Retrival and analysis of a HGD confirmed as those seen at ultrasound     
  10. The association of CBD stones with HGD.