Ultrasound evaluation of the gallbladder and common bile

duct remains the best test for identifying cholecystitis. The

sensitivity ( 88-94%) and specificity ( 80-90%) vary

depending on what criteria are used to establish the diagnosis. On ultrasound examination, gallstones appear as

hyperechoic intraluminal structures, and larger stones will

cast an ultrasound shadow (Figure 28-1 ). Findings suggestive

of cholecystitis include gallbladder wall thickness greater

than 3-5 mm and pericholecystic fluid. A common bile

duct diameter greater than S-8 mm is abnormal. The

sonographic Murphy sign is positive when maximal pain is

produced with transducer pressure over the gallbladder.

When combined with the presence of gallstones, the sono ­

graphic Murphy sign has a positive predictive value of

92%. The sonographic Murphy sign can be masked by

Figure 28-1. Short axis view of the gall bladder

demonstrating a gall bladder neck stone (large arrow)

and gallbladder wall thickening (small arrows).

© casey Glass, MD.

ACUTE CHOLECYSTITIS

Figure 28-2. Abdominal CT sca n showing an enlarged gallbladder with

pericholecystic fluid (black arrows) and a di lated common bile duct

(white arrow). © Casey Glass, MD.

prior pain medication and can be absent in diabetics or

gangrenous cholecystitis.

Abdominal computed tomography (CT) scan is helpful

when other diagnoses are also being considered. CT scanning is less sensitive for acute cholecystitis than ultrasound

( 50-90%), but is as sensitive for choledocholithiasis and can

identify complications such as perforation or abscess formation. CT findings include wall thickening, pericholecystic fluid, and biliary tree dilation (Figure 28-2). Notably,

only 20% of gallstones are radio-opaque, which limits the

utility of CT in early cases of cholecystitis or for patients

with biliary colic.

MEDICAL DECISION MAKING

The patient with classic symptoms of biliary colic or acute

cholecystitis is easy to identify, but many patients present

with atypical symptoms (Figure 28-3). It is important to

consider other conditions that may masquerade as gall ­

bladder pain. This may include pyelonephritis of the right

kidney or retrocecal appendicitis. Right lower lobe pneumonia can also present with right upper quadrant pain

and vomiting. Patients with choledocholithiasis are often

misdiagnosed as having pancreatitis or gastritis. In elderly

patients or those with coronary disease, it is important to

consider the possibility of an inferior myocardial infarc ­

tion. Patients who appear septic or with peritoneal signs

may have perforation or ascending cholangitis. Other gastrointestinal (GI) conditions such as pancreatitis, peptic

ulcer disease, or hepatitis should also be considered.

lab tests, IV flu ids, pain

meds

• Reeva luate the patient

• Consider alternate diagnoses

• If suspicion remains high, consider

abdominal CT scan and/or admission.

.A Figure 28-3. Acute cholecystitis diagnostic algorithm.

CT, computed tomography; IV, intravenous; RUQ, right

upper quadrant.

CHAPTER 28