Bedside Ultrasonography for Gallbladder Disease

Updated: Sep 20, 2015
  • Author: Timothy Jang, MD; Chief Editor: Caroline R Taylor, MD  more...
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Overview

Overview

Hepatobiliary disease is a common problem in patients presenting to emergency departments or primary care settings. Unfortunately, clinical examinations and laboratory evaluations lack the necessary sensitivity and specificity to accurately diagnose many of these entities without further testing. [1] Focused bedside ultrasonography (BUS) is an increasingly available and helpful diagnostic tool that can further evaluate patients with suspected biliary disease. [2] In a recent study, test characteristics of emergency physician bedside ultrasonography were similar to that of radiology performed ultrasonography for detection of cholecystitis. [3] Bedside ultrasonography for gallbladder disease is also a skill that can be learned by physicians at all levels of training. [4]

The benefits of focused bedside biliary sonography include the following:

  • Decreases the time to diagnosis for cholelithiasis and cholecystitis [5]
  • Helps accurately diagnose biliary pathology [5, 6] . Sensitivity of 90-96%, Specificty of 88-96%, positive predictive value 88-99%, and a negative predictive value of 73-96%. [7]
  • Helps assess the degree of obstruction in choledocholithiasis
  • Can help diagnose gallstones definitively, which makes alternative diagnoses less likely [8]
  • Can be performed rapidly at the bedside
  • Can provide bedside radiographic corroboration of physical examination findings for the treating physician
  • Does not involve ionizing radiation and, as such, is safe in pregnant patients and children [9]

Contrast-enhanced ultrasound is a minimally invasive diagnostic technique that is useful in visualizing not only the shape of cancer lesions and some areas of direct invasion to the liver, but also metastasis. [10]

For more information, see the Medscape Gallbladder and Biliary Disease Resource Center.

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Indications

Patients that present with history and physical exams consistent with biliary disease should undergo a focused bedside biliarysonography. Such signs and symptoms include:

  • Abdominal pain associated with ingestion of food
  • Colicky right upper quadrant or epigastric abdominal pain
  • Jaundice
  • Atypical right-sided chest or shoulder pain
  • Abnormal liver function laboratory studies

As per the American College of Emergency Physician’s Policy Statement , indications for focused bedside biliarysonography include the following: [11]

  • Primary
    • Identification of chlelithiasis
  • Extended
    • Cholecystitis
    • Common bile duct abnormalities, including dilation and choledocholithiaisis
    • Liver abnormalities, including tumors, abscesses, intrahepaticcholestasis, pneumobilia, hepatomegaly
    • Portal vein abnormalities
    • Other Gallbladder abnormalities, including tumors
    • Unexplained jaundice
    • Ascites.

When findings concerning for hepatic malignancy are found incidentally on BUS, care must be taken to instruct the patient regarding further follow-up. These patients will need further imaging (ie, computed tomography scan) and work-up.

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Contraindications

When emergent treatments such as intravenous fluids, antibiotics, or pressors are indicated, performance of abdominal sonography should not delay the initiation of these treatments. Ongoing resuscitation and extremis, however, are not contraindications. While challenging to perform in such situations, bedside biliary sonography can be easily incorporated into the flow of patient care.

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Anesthesia

Anesthesia is generally not necessary for abdominal sonography; however, pain management should not be delayed and patients may experience some discomfort due to probe pressure. For improved patient comfort, consider using warmed ultrasound conducting gel, if available.

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Equipment

See the list below:

  • Ultrasound machine with color flow Doppler
  • Low frequency (2-5 MHz) curvilinear or phased array transducer
  • Acoustic coupling gel
  • Appropriate materials to drape the patient
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Positioning

Patients should be evaluated in the supine position but can be positioned in the upright, standing, or left lateral decubitus positions for improved visualization. Male patients should have their entire right hemithorax exposed for the examination. Take care with female patients to drape appropriately and to minimize exposure of sensitive areas.

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Technique

Relevant anatomy

The gallbladder is superior and anterior to the right kidney. It typically lies between the right and quadrate lobes of the liver in a slightly oblique position. Landmarks for the gallbladder are the undivided right portal vein and the main lobar fissure. The main lobar fissure is a bright, hyperechoic line that extends from the right portal vein to the gallbladder fossa. The main lobar fissure is the functional division of the liver (divides right and left lobes) and is seen in most patients; however, it may be short or absent in some patients. The gallbladder neck tapers into the cystic duct. The common bile duct (CBD) travels anterior to the portal vein and right of the hepatic artery. See the image below.

Cine loop depicting a normal gallbladder. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.

For more information about the relevant anatomy, see Gallbladder Anatomy.

Components of examination

The key components of the biliary ultrasound include the following [11] :

  • Transverse and longitudinal views of the gallbladder with clear anatomical relationship to the liver, kidney, and portal vein for unambiguous identification
  • Gallbladder wall thickness
  • Presence or absence of gallstones
  • Presence or absence of biliary sludge
  • Presence or absence of pericholecystic fluid
  • Diameter of the common bile duct
  • Presence or absence of the sonographic Murphy sign

The examination can be technically limited by obese habitus, bowel gas, and/or abdominal tenderness. [11]

Technique

With the patient in the supine position, place the probe in the right upper quadrant.

Once the gallbladder is clearly identified, obtain longitudinal and transverse views of the gallbladder. See the images below.

Longitudinal probe placement for biliary ultrasono Longitudinal probe placement for biliary ultrasonography with the indicator pointed toward the patient's head (cephalad).
Longitudinal view of gallbladder. Longitudinal view of gallbladder.
Transverse probe placement for biliary ultrasonogr Transverse probe placement for biliary ultrasonography with the indicator pointing to the patient's right.

If stones are seen, obtain a dependent view (upright, standing, or left lateral decubitus) to assess the mobility of the stones. See the images below.

Left lateral decubitus probe placement. Left lateral decubitus probe placement.
Left lateral decubitus view of gallbladder. Left lateral decubitus view of gallbladder.

Use the liver as an acoustic window. If the gallbladder cannot be visualized (because of bowel gas or a more lateral or cephalad location of the gallbladder), try moving laterally or superiorly. Moving the probe cephalad may necessitate scanning through or between the right lower ribs; in such cases, consider switching to a phased array probe, which has a smaller footprint and is easier to position between the ribs. See the image below.

View of gallbladder using the liver as an acoustic View of gallbladder using the liver as an acoustic window.

The video below depicts a demonstration of biliary evaluation.

Demonstration of ultrasonographic biliary evaluation. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.

Ultrasonographic criteria

Most gallstones produce acoustic shadows. See the image below.

View of gallstone. View of gallstone.

Gallstones typically demonstrate gravitational dependency and mobility. See the image below.

View of gallstone. View of gallstone.

Cholesterol stones and stones smaller than 1 mm may not produce prominent shadows; they may instead result in a hazy appearance posteriorly. Nonshadowing, nonmobile, round-appearing masses can be polyps.

Sludge is less echogenic than stones, does not shadow, forms a fluid level, and moves slowly compared to stones.

Findings that suggest acute cholecystitis include gallbladder wall thickening (> 4 mm), double wall sign, pericholecystic fluid, or a sonographic Murphy sign (pain elicited by pressing the ultrasound probe over the fundus of the gallbladder). [12] See the image below.

Gallbladder wall thickening with edema. Gallbladder wall thickening with edema.

Gallbladder wall thickening may be seen in nonbiliary pathologic states such as the postprandial state, hypoproteinemia, chronic liver disease (hepatitis, cirrhosis), pancreatitis, HIV infection, and congestive heart failure. [13, 11] See the image below.

Gallbladder wall thickening with edema, seen in tr Gallbladder wall thickening with edema, seen in transverse view.

Common bile duct diameters range from 4-10 mm, depending on a patient’s age (normal is 3-4 mm; add 1 mm for every 10 years after age 40 years). Patients who are status post cholecystectomy can have common bile ducts up to 10 mm in size. A dilated common bile duct can suggest choledocholithiasis, cholecystitis, or biliary obstruction. [14]  In a study of ultrasound measurements of the bile ducts and gallbladder, the gallbladder wall was found to be thicker in patients with gallstones (+0.4 ± 1.4 mm, P = 0.0049), sludge (+0.5 ± 1.4 mm, P = 0.0019), and acute cholecystitis (+3.1 ± 1.6 mm, P <0.0001). With biliary obstruction, the extrahepatic bile duct, right duct, left duct, and gallbladder volume measurements were 6.0 ± 2.1 mm, 4.2 ± 1.4 mm, 4.1 ± 1.4 mm, and 171 ± 207 mL, respectively (P <0.0001 for all values). [14] See the image below.

View of gallstone with dilation of cystic duct. View of gallstone with dilation of cystic duct.

The video below depicts cholecystitis.

Cine loop depicting cholecystitis. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.

Causes of false-positive and false-negative studies are as follows [11, 15] :

  • Small gallstones - Overlooked or mistaken for gas in the adjacent loop of bowel
  • Gas in the loops of bowel adjacent to the posterior wall of the gallbladder
  • Small stones in the gallbladder neck
  • Polyps mistaken for gallstones
  • Mistaking the gallbladder for other fluid-filled structures, including the portal vein, the inferior vena cava, and hepatic or renal cysts
  • Failure to identify the gallbladder may occur with chronic cholecystiti, particularly when filled with stones
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Pearls

See the list below:

  • If the gallbladder is difficult to visualize, consider repositioning the patient into an upright, standing, or left lateral decubitus position. Asking the patient to take and hold a deep breath results in downward excursion of the diaphragm and may bring the gallbladder down and out from beneath the costal margin.
  • If the patient is very thin or has an anterior gallbladder, consider increasing the frequency to 5 MHz.
  • Though rare, in chronic congenital conditions like Caroli syndrome, biliary duct dilatation can observed.
  • Nonshadowing, nonmobile, round-appearing masses can be polyps. Patients with indeterminate or suspicious masses should receive further imaging and work-up. Consider obtaining a comprehensive ultrasonographic examination and having the patient follow up with their primary care provider.
  • Many patients with biliary cancer also have gallstones and can develop a calcified gallbladder wall with focal thickening. [16] Calcified gallbladders, also known as porcelain gallbladders, have a high frequency (up to 22%) of association with adenocarcinoma. In patients with calcified gallbladders or with suspected biliary cancer, further imaging and work-up are indicated.
  • If gallbladder cysts or masses are identified, patients should receive further imaging and work-up. Consider obtaining a comprehensive ultrasonographic examination and having the patient follow up with their primary care provider.
  • Mucosal folds (ie, junctional fold or Phrygian cap) within the gallbladder are common. Caution must be used to not misinterpret them as septae, polyps, or stones.
  • Common pitfalls include the following:
    • Failure to visualize the entire gallbladder, resulting in missed gallstones; in particular, stones in the neck of the gallbladder
    • Misinterpreting artifacts (side lobe artifact, edge artifact) as pathology
    • Misinterpreting scattering from adjacent small bowel as acoustic shadowing
    • Attempting to interpret inadequate or technically limited studies
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Complications

No complications are typically associated with bedside sonography. Not recognizing one's limitations and abilities, however, can result in false positive and false negative studies.

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