Bedside Ultrasonography for Gallbladder Disease 

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]

The benefits of focused bedside biliary sonography include the following:

• Decreases the time to diagnosis for cholelithiasis and cholecystitis^[4]
• Helps accurately diagnose biliary pathology^{[4, 5]}
• Helps assess the degree of obstruction in choledocholithiasis
• Can help diagnose gallstones definitively, which makes alternative diagnoses less likely^[6]
• 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^[7]

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

Indications for focused bedside biliary sonography include the following:

• 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

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.

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.

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.

• 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

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.

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.

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

Components of examination

Focused bedside biliary sonography should include transverse and longitudinal views of the gallbladder with clear anatomical relationship to the liver, kidney, and portal vein for unambiguous identification. In addition, a dependent view (upright, standing, or left lateral decubitus) should also be obtained when stones are seen to determine if they are mobile.

Technique

1. 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.Longitudinal probe placement for biliary ultrasonography with the indicator pointed toward the patient's head (cephalad). Longitudinal view of gallbladder. 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.Left lateral decubitus probe placement. 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.View of gallbladder using the liver as an acoustic window.

The video below depicts a demonstration of biliary evaluation.

Ultrasonographic criteria

Most gallstones produce acoustic shadows.View of gallstone. Gallstones typically demonstrate gravitational dependency and mobility.View of gallstone.
1. Cholesterol stones and stones smaller than 1 mm may not produce prominent shadows; they may instead result in a hazy appearance posteriorly.
2. 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's sign (pain elicited by pressing the ultrasound probe over the fundus of the gallbladder).Gallbladder wall thickening with edema. Gallbladder wall thickening with edema, seen in transverse view. Common bile duct (CBD) 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 CBDs up to 10 mm in size. A dilated common bile duct can suggest choledocholithiasis, cholecystitis, or biliary obstruction.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.

• 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.
• Gallbladder wall thickening may also be seen in patients with ascites, congestive heart failure (CHF), hypoalbuminemia, chronic liver disease (hepatitis), pancreatitis, or HIV, and may be seen postprandially in patients with a contracted gallbladder.^[8]
• 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.^[9] 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

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.