Bedside Ultrasound of the Biliary Tract

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Bedside Ultrasound of the Biliary Tract

• Gary Quick, M.D., FACEP

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Objectives

• Clinical indications for performing directed ED
  US
• Approach to performing biliary tract imaging
• Normal exam findings
• Abnormal findings
• Clinical impact
• Problems/Pitfalls
• Case Presentations

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Diagnostic Modalities

• Oral cholecystography (HIDA)
• Computed tomography (CT)
• Magnetic resonance imaging (MRI)
• Ultrasound

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Case History
A 30 y.o. female presents with C/C of epigastric
pain, nausea and vomiting for the past 6 hr. The
pain is sharp, intermittent, and doubles her over
at its peak intensity. The pain is located in
the RUQ and radiates to her back. She had an
appendectomy 5 yr. prior
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Case History
On physical examination she is afebrile with
normal vital signs. She appears uncomfortable
and vomits bilious material twice in the ED. She
has midepigastric tenderness, no guarding, masses
or hepatosplenomegaly and no CVA tenderness.
Murphys sign is absent. Pelvic and rectal exams
are normal.
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Case History
Within 5 min., a focused bedside US is performed
by the EP. The GB is 3 cm in diameter with
anterior wall lt 2 mm thick. CBD measures 4 mm in
diameter. There is a positive ultrasonic
Murphys sign.The GB contains a large hyperechoic
structure that casts an acoustic shadow
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Clinical Indications for Bedside US of the
Biliary Tract

• Clinical presentation consistent with symptomatic
  cholelithiasis
• Undifferentiated epigastric/RUQ pain
• Jaundice

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Clinical Impact of Bedside Biliary Tract Imaging

• Rapid, accurate modality for diagnosis of
  cholelithiasis
• Ultrasonic Murphys sign allows corroboration of
  physical findings
• Fast and noninvasive
• No radiation or contrast exposure
• Performed at the bedside
• Cost-effective procedure

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Incidence of Biliary Tract Disease

• Cholelithiasis affects gt 15 million in U.S.
• Contributes to 6-10,000 deaths annually
• gt500,000 cholecystectomies per year
• Annual cost of surgery gt 3 billion
• Majority of gallstones clinically silent
• 18-50 become symptomatic over 10-15 yr

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Performance and Accuracy of RUQ US by EPs
Kendall JL, Shimp RJ. Performance and
interpretation of focused right upper quadrant
ultrasound by emergency physicians, J Emerg Med
2001 Jul21(1)7-13 EP RUQ US v. formal RUQ
US 109 pts. enrolled 51 with stones 49 detected
by EPs. Sensitivity 96.
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Performance and Accuracy cont.
58 without stones 51 correctly identified by
EPs Specificity 88 83 of emergency studies
completed in lt 10 min. Conclusion Gallstones
accurately detected by EPs in timely fashion.
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Acute Cholecystitis

• Correlation Among Clinical, Laboratory, and
  Hepatobiliary Scanning Findings in Patients With
  Suspected Acute Cholecystitis
• AJ Singer, Ann Emerg Med 1996283267-272.
• No single or combination of clinical or
  laboratory findings at the time of ED
  presentation identified all patients with (acute
  cholecystitis).

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Acute Cholecystitis

• Correlation Among Clinical, Laboratory, and
  Hepatobiliary Scanning Findings in Patients With
  Suspected Acute Cholecystitis
• AJ Singer, Ann Emerg Med 1996283267-272.
• Liberal use of . . . . ultrasound is encouraged
  to avoid underdiagnosis of acute cholecystitis.

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If you use fever and an elevated white count as
your criteria for diagnosing cholecystitis in the
ED, you will misdiagnose 20 of these cases.
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Bedside US Diagnostic Applications
Bedside US facilitates diagnosis of

• Congenital anomalies
• Cholelithiasis
• Acute and chronic cholecystitis

• Gallbladder sludge
• Gallbladder cancer
• Adenomyomatosis

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Uncommon Gallbladder Anomalies

• Agenesis
• Hypoplasia
• Hyperplasia
• Total reduplication
• Subtotal division of fundus
• Phrygian cap
• Septated gallbladder

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Technical Considerations

• Knowledge of US physics and machine operation
• Anatomic relationships
• Patient preparation
• Patient positioning
• Probe positioning

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Skin Preparation and Probe Selection

• Appropriate conductive medium (US gel) reduces
  skin artifact enhancing image quality
• For general abdominal imaging use
• 3.5 MHz probe. 5 MHz may suffice in child

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Patient Preparation

• 6-8 hr. fasting period for elective scanning not
  as critical for acutely ill pt
• If pt has recently eaten
• Small contracted gallobladder
• Increased wall thickness
• GB often distended in acute illness due to poor
  oral intake, abdominal pathology, or biliary
  tract obstruction

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Patient Positioning

• Usually begin with pt supine
• Utilize at least two positions for exam
• Provide better or multiple views of pathology
• Demonstrate stone or sludge movement
• Left or right lateral decubitus, left posterior
  oblique, partially upright, or prone

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Probe Positioning

• Function of personal preference, experience and
  patient body habitus
• Employ liver as hepatic window.
• Alternate window is retroperitoneum.
• Anterior subcostal, coronal, right posterior
  oblique
• Visualize the portal triad

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Portal vein
GB
R kidney
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Right Upper Quadrant Anatomy

• Liver
• Gallbladder
• Biliary tree
• Head of pancreas
• Upper pole R kidney

• Portions of stomach and duodenum
• Hepatic flexure
• Vascular structures
• Retroperitoneal structures

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RUQ Anatomy
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RUQ Anatomy GB Location

• GB lies inferior to liver
• Between the right and quadrate hepatic lobes
• Hollow viscus in the gallbladder fossa
• Consists of fundus, body, and neck
• Neck tapers to cystic duct

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Sonographic Appearance of Gallbladder

• Fluid-filled structure
• 3-layered wall
• Strongly reflective outer layer
• Minimally reflective inner layer
• Anechoic layer between
• Wall thickness lt 2 mm. in 97

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Anatomy of Common Bile Duct

• CBD is tethered to liver at juncture of right
  and left hepatic ducts and enters duodenum
  distally through ampulla of Vater
• CBD passes across and then parallel to portal
  vein coursing along the hepatoduodenal ligament

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CBD
CBD

• CBD internal diameter is lt 4 mm in 98 of normal
  individuals
• Cystic duct 1.8 mm diameter and 1-2 cm long

Portal vein
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CBD Scanning Tips

• Roll pt 45 into left posterior oblique
• Scan with transducer perpendicular to costal
  margin
• Tweak transducer to image longest portion of
  portal vein .
• CBD should lie anterior to (above on screen)
  portal vein.
• CBD crosses then parallels the portal vein

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Gallbladder Scanning Problems

• Small liver, anterior GB, or bowel gas
• Have pt sit up or roll to left to enlarge hepatic
  window.
• Scan thin pt or anterior GB with 5 mHz transducer

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Pathologic Conditions of the Biliary Tract

• Cholelithiasis
• Cholecystitis
• Sludge
• Cancer
• Adenomyomatosis

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Cholelithiasis

• Prevalence 6-10 men, 12-20 women
• Three types of stone
• Mixed cholesterol 80
• Pure cholesterol 10
• Pigment 10
• 18-50 become symptomatic over 10-15 yr.

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Processes of Gallstone Formation

• Abnormal bile production
• Bile stasis
• Infection

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Scanning Considerations Cholelithiasis

• Accuracy 90-95
• Liver as acoustic window
• Location inferior hepatic surface, medial and
  anterior to kidney, lateral and anterior to vena
  cava

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Ultrasonic Criteria for Cholelithiasis

• Intraluminal brightly echogenic structure
• Stones gt 3mm will produce an acoustic shadow
• Stones will usually seek gravitational dependency

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Image Patterns Cholelithiasis

• Stones with shadowing
• Stones without shadowing
• Gravel
• GB filled with stones
• Floating stones as fluid level in bile
• Adherent Gallstones
• Dilation of common bile duct

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Large stone with shadowing
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Many small stones
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Layer of gravel with shadowing
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Cholecystitis

• Represents both acute and chronic inflammation
• Risk factors obstruction and bile stasis
• Bacterial growth common but secondary
• Acute cholecystitis fever, chills, RUQ pain and
  leukocytosis, jaundice, and positive Murphys.
  Acalculous cholecystititis 1- 5

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Acute Cholecystitis
Fever and Leukocytosis in Acute Cholecystitis
Gruber PJ,Annals EM 1996283,277-279
patients with acute cholecystitis in the ED
frequently lacked fever and leukocytosis. The
clinician should not rely on these findings in
making the diagnosis of acute cholecystitis.
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Acute Cholecystitis

• Age gt 70 yr
• Women lt 40 yr
• 1.5 X greater for acute cholecystitis
• 5 X greater for chronic cholecystitis

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Acute Cholecystitis Complications

• Gangrenous cholecystitis
• Gallbladder perforation
• Pericholecystic abscess formation
• Sepsis
• Peritonitis
• Ascending cholangitis
• Peritoneal abscess formation
• Cholecystoenteric fistula

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Scanning Considerations Cholecystitis

• Cholelithiasis
• Stones present in the majority of cases.
• If no stones, consider acalculous cholecystitis.
  
• Increased transverse GB diameter gt4-5 cm
• GB wall thickness gt 4-5 mm (anterior wall)
• Averages 5 mm in acute cholecystitis
• Averages 9 mm in chronic cholecystitis

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Additional Sonographic findings

• Decreased echogeneity of the entire wall
• Sonographic Murphys sign
• Pericholecystic fluid
• Diffuse, homogeneous echogeneity with GB lumen
  (pus in lumen or GB empyema)

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Acute cholecystitis
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Sonographic Murphys Sign

• Place the probe directly over the gallbladder and
  apply pressure
• Reproduction of the patients symptoms is highly
  suggestive of symptomatic cholelithiasis or acute
  cholecystitis
• Look for gallbladder wall thickening, increased
  transverse diameter of the gallbladder and
  pericholestistic fluid indicating obstrcution
  and/or inflammation

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Gallbladder wall thickening

• Present in many non-inflammatory conditions
• Post-prandial most common
• Congestive heart failure
• Starvation/hypoproteinemic states
• Ascites
• HIV

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Thickened gb wall with stone
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Contracted gb w/ wall thickening
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Gallbladder Sludge

• Equals echogenic bile
• May represent biliary tract disease or benign
  bile stasis with increased pigment
• Clinical association with hyperalimentation,
  hemolysis, fasting, pregnancy, post-op state, and
  cirrhosis

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Gallbladder Sludge

• Differentiate from hematobilia, biliary tract
  tumors, and purulent bile.
• May hide stones
• Found on 2 of RUQ US
• Serial studies if asymptomatic
• but treat aggressively if thickened wall,
  pericholecystic fluid or sonographic Murphys

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Scanning Considerations Sludge

• Sludge is slow-moving compared to stones
• When sludge is present, look for
• Gallstones floating or hidden within
• Cholecystitis Murphys, wall-thickening
• Polyps medium density adherent to wall
• Malignancy filled with solid masses or focal
  masses within thickened walls.

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Sludge
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Gallbladder Cancer

• 1-2 of all GI malignancies
• 75 of GB Ca patients have cholelithiasis
• Focal wall thickening, typically in fundus
• Lumen filled with tumor mass wall calcified
  (porcelain gallbladder)

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Scanning ConsiderationsCancer

• High rate of false positives and false negatives
• Patterns aiding recognition
• Gallbladder mass complex, partially or
  completely filling lumen
• Diffuse wall thickening
• Polypoid or fungating intraluminal masses

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Take Home Points

• Reposition the patient on their left side or have
  them breathe to optimize imaging windows
• Stones can be incidental presence of a
  sonographic Murphys sign important
• The acuostic shadow may be the only songraphic
  sign of a stone
• All echogenic masses/shadowing within the GB or
  asymmetric wall thickening should be followed up
  closely!