Cholelithiasis without sonographic evidence of acute cholecystitis

IMAGING

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Ultrasound findings

Cholelithiasis, sonographic Murphy sign, and GB wall thickening

CT findings

Distended GB (measuring > 5 cm in short axis)

GB wall thickening (> 3 mm) with mural and mucosal hyperenhancement and pericholecystic fat stranding

Calcified gallstones may be visualized (15% of cases)

Hyperenhancement of adjacent liver parenchyma

Hepatobiliary scintigraphy (Tc99-HIDA)

Nonvisualization of GB 4 hours after injection of radiotracer (or 30 minutes after administration of morphine)

Complications

Gangrenous cholecystitis: GB wall necrosis with ↑ morbidity/mortality

Perforated cholecystitis: Most often occurs due to progressive GB distension with eventual rupture

Emphysematous cholecystitis: Secondary infection of GB with gas-forming organisms

Hemorrhagic cholecystitis: Hemorrhage within GB lumen or wall

Gallbladder

Tenderness and guarding in the right hypochondrium exacerbated by inspiration (Murphy sign) suggests acute cholecystitis (see Chapter 33). If the gallbladder is palpable in the presence of obstructive jaundice, this suggests malignant obstruction of the biliary tree (Couvoisier law), which is commonly due to carcinoma in the head of the pancreas (see Chapter 62). Failure to palpate the gallbladder does not exclude malignant disease, however, and a nonpalpable gallbladder is the rule in malignant obstruction at the hilus of the liver. A gallbladder that is intermittently palpable may suggest the presence of a periampullary carcinoma (Kennedy & Blumgart, 1971). Gallbladder distension and signs of sepsis in the presence of gallstones may indicate empyema of the gallbladder. In such instances, initial treatment consists of percutaneous aspiration and drainage, with a cholecystectomy delayed for some time. Alternatively, an urgent cholecystectomy may be performed.

C CHOLECYSTITIS (SEE EBM Box 48-3)

In patients with right upper quadrant pain and suspected cholecystitis, a positive Murphy's sign argues modestly for cholecystitis (LR = 1.9). The presence of back tenderness argues somewhat against cholecystitis (LR = 0.4), probably because it is more commonly found in alternative diagnoses such as renal disease or pancreatitis.67 The presence or absence of a right upper quadrant mass is unhelpful, probably because a palpable tender gallbladder is uncommon in cholecystitis (sensitivity <25%) and because the sensation of a right upper quadrant mass may occur in other diagnoses, such as liver disease or localized rigidity of the abdominal wall from other disorders.

There is also a “sonographic Murphy's sign,” elicited during ultrasonography of the right upper quadrant, which is simply the finding of maximal tenderness over the gallbladder. Studies of this sign in patients with right upper quadrant pain reveal much better diagnostic accuracy than conventional palpation: sensitivity 63%, specificity 94%, positive LR = 9.9, and negative LR = 0.4.68 The superior accuracy of this sign, which also relies on palpation of the abdominal wall, suggests that the poorer accuracy of conventional palpation is due to the difficulty precisely locating the position of the gallbladder.

Murphy's sign may be even less accurate in elderly patients, because up to 25% of patients older than 60 years of age with cholecystitis lack any abdominal tenderness whatsoever.69 Although most of these patients have abdominal pain, some have altered mental status and lack this symptom as well.

In patients with a pyogenic liver abscess, the presence of Murphy's sign argues that the patient has associated biliary tract sepsis (sensitivity 32%, specificity 88%, positive LR 2.8, negative LR not significant).70

Helpful Clues for Common Diagnoses

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Acute Calculous Cholecystitis

Clinical: RUQ pain, fever, positive Murphy sign

Acute gallbladder (GB) inflammation secondary to calculus obstructing cystic duct

Gallstones ± impaction in GB neck

Diffuse GB wall thickening (> 3 mm)

Striated appearance: Alternating bright and dark bands within thick GB wall

GB wall lucency halo sign: Sonolucent middle layer due to edema

Distended gallbladder (GB hydrops)

Positive sonographic Murphy sign

Presence of pericholecystic fluid

Complicated cholecystitis

Gangrenous cholecystitis

Asymmetric wall thickening

Marked wall irregularities

Intraluminal membranes

GB perforation

Defect in GB wall

Pericholecystic abscess or extraluminal stones

Emphysematous cholecystitis

Gas in GB wall/lumen

Empyema of GB

Intraluminal echoes, purulent exudate/debris

Chronic Cholecystitis

Mostly asymptomatic

Diffuse GB wall thickening

Mean thickness ~ 5 mm

Smooth/irregular contour

Contracted GB

GB lumen may be obliterated in severe cases

Presence of gallstones in nearly all cases

Hyperplastic Cholecystosis (Adenomyomatosis)

Adenomyomatosis of GB

Clinically asymptomatic, usually incidental US finding

Focal or diffuse GB wall thickening

Tiny echogenic foci in GB wall producing comet-tail artifacts

Presence of cystic spaces within GB wall

Fundal adenomyomatosis: Smooth thickening or focal mass in fundal region ± ring down artifact

Hourglass GB: Narrowing of mid portion of GB

Wall Thickening Due To Systemic Diseases

Clinical correlation is key to explain presence of GB wall thickening

Appearance of wall thickening is nonspecific

Other ancillary US findings

Congestive heart failure : Engorged hepatic veins and IVC, diffuse hypoechoic liver echo pattern

Renal failure : Small kidneys with increased parenchymal echogenicity

Hepatic cirrhosis : Coarse liver echo pattern, irregular/nodular liver contour, signs of portal hypertension (e.g., ascites, splenomegaly, varices)

Hypoalbuminemia : Presence of ascites, diffuse bowel wall thickening

IMAGING

Ultrasound

The ultrasound findings in acute uncomplicated cholecystitis are well described and include gallstones, sonographic Murphy sign, gallbladder distention, wall thickening, and pericholecystic fluid26,27,39-41 (Figs. 77-15 and 77-16). The sonographic Murphy sign refers to maximum tenderness during compression with the ultrasound transducer placed directly over the gallbladder. Of these findings, the first two are considered the most specific. In a study by Ralls and coworkers,42 the sonographic Murphy sign and the presence of gallstones had a positive predictive value of 92% for the diagnosis of acute cholecystitis. It is cautioned that the sonographic Murphy sign may be blunted if the patient has received pain medication before ultrasound evaluation. Furthermore, impaired mental status may preclude evaluation of this sign. Last, the sonographic Murphy sign may be absent in the setting of gangrenous cholecystitis (see later). If it can be demonstrated that a stone is impacted in the gallbladder neck or cystic duct, this is also an important finding that increases the likelihood of acute cholecystitis (Fig. 77-15B). To determine that a stone is impacted in the gallbladder neck or cystic duct requires evaluating the patient in the left lateral decubitus or upright position to assess for mobility of the stone.

Less specific ultrasound findings of acute cholecystitis include gallbladder distention, wall thickening, pericholecystic fluid, and the presence of other intraluminal material such as sludge. In most cases of acute cholecystitis, the gallbladder will be distended. An exception to this occurs when acute cholecystitis complicates chronic cholecystitis, when there may be mural fibrosis impeding distention. Also, if there has been free perforation of the gallbladder, it may appear completely collapsed (discussed further later). Diffuse gallbladder wall thickening, measuring more than 3 mm, is present in 50% to 75% of patients with acute cholecystitis but may also be associated with chronic inflammation.26 Furthermore, gallbladder wall thickening may be associated with many other conditions, including liver disease such as acute hepatitis (Fig. 77-17), ascites, hypoalbuminemia, and alcoholism as well as congestive heart failure, acquired immunodeficiency syndrome (AIDS), and sepsis. In patients with AIDS, cholangiopathy may be related to infection with organisms such as Cryptosporidium. Other causes include adenomyomatosis and gallbladder neoplasm. In acute cholecystitis, wall thickening is generally diffuse; if it is more focal, a complication such as gangrenous change or another cause, such as neoplasm, should be considered. Pericholecystic fluid is generally associated with more severe cholecystitis and may be associated with perforation or abscess formation. However, this may also be nonspecific, especially in the setting of generalized ascites. Other entities that clinically can mimic acute cholecystitis, such as peptic ulcer disease and pancreatitis, may also be associated with pericholecystic fluid. Sludge, related to bile stasis, can develop in patients with acute cholecystitis due to gallbladder obstruction.

The role of color and power Doppler evaluation as an adjunct to gray-scale imaging in the diagnosis of acute cholecystitis is somewhat controversial. Although there may be overlap between findings in acute and chronic cholecystitis,43 there may be a potential role for Doppler evaluation of the inflamed gallbladder44 (Fig. 77-18).

45 What characteristic features of AIDS are seen in the biliary system?

There are three main categories of biliary disease in AIDS patients: non–HIV-associated pathology, acalculous cholecystitis, and AIDS cholangiopathy.

Gallstones and benign bile duct strictures can also be seen in AIDS patients and should be excluded.

Acalculous cholecystitis, which manifests with gallbladder wall thickening, pericholecystic fluid, and a sonographic Murphy sign, is usually seen in patients with concurrent CMV or Cryptosporidium infection as well as sclerosing cholangitis or papillary stenosis. Cholecystectomy is usually an effective treatment.

HIV or AIDS-related cholangiopathy is usually secondary to infection with Cryptosporidium or less commonly CMV and typically occurs in patients with CD4 counts less than 100. US is often initially performed, and a negative exam virtually excludes the diagnosis. ERCP or MRCP displays the morphologic appearance of the entire ductal system better than US or CT. Irregular extrahepatic and intrahepatic (left greater than right) dilated ducts, beading of the mucosa, wall thickening, papillary narrowing, diffuse intrahepatic or extrahepatic strictures, intraductal debris, or any combination of these findings can be seen in AIDS-related cholangitis. These findings may mimic those of sclerosing cholangitis, papillary stenosis, or both. With the advent of newer antiretroviral therapy, the incidence has decreased substantially.

Biliary ductal dilatation can also be caused by obstruction from enlarged lymph nodes in the porta hepatis from Kaposi sarcoma (KS) or lymphoma. Non–AIDS-related conditions, such as biliary calculi, cholangiocarcinoma, or pancreatic carcinoma, also may be a consideration. A search for these entities should be made in the appropriate clinical setting.