|ECR 2018 / C-2873|
|Gallbladder disorders: ultrasound as a first-line imaging examination|
Ultrasound remains the first-line examination when a gallbladder disorder is suspected, because of its multiple advantages, as the lack of ionizing radiation, great availability, short study time, morphologic evaluation and the possibility of identifying associated biliary pathology and alternative diagnosis. 
At emergency departments, ultrasound allows the identification of acute cholecystitis and its more advanced/dangerous forms, as gangrenous and emphysematous cholecystitis. Thus, the radiologist must be able to recognize its sonographic findings so that treatment can be initiated as soon as possible.
Also important is to be able to identify uncommon pathology as neoplastic lesions and therefore increased risk of malignancy.
Differentiation of benign and malignant polyps is essential because benign masses are common and malignant polyps require early intervention to improve outcome. Multiple masses and size up to 10 mm are the most frequently used criteria for benignity 
Ultrasound artifacts and pathological correlation have an important role in the differential diagnosis of GD.
Other imaging examinations, as CT and MRI, are needed when sonography excluded GD, complications of cholecystitis are suspected and cases in which the differential diagnosis includes both inflammatory and neoplastic pathology. 
As a first-line imaging examination of suspected GD, an accurate interpretation of ultrasonographic findings reduces the need for more expensive and time-consuming or radiation associated examinations, like MRI or CT.