Repeat Biliary Point of Care Ultrasound for Detecting Early Acute Cholecystitis

Acute cholecystitis is a frequent cause of abdominal pain leading to emergency department (ED) evaluation and accounts for approximately 200,000 cases annually in the US (1). Ultrasound (US) is the first-line diagnostic test, but early disease may produce equivocal or negative findings. This diagnostic uncertainty can lead to delayed treatment or the need for additional imaging, such as computed tomography (CT) or a hepatobiliary iminodiacetic acid (HIDA) scan. Recent research has shown that inflammatory changes of the gallbladder may evolve over several hours during the acute presentation. Repeat point-of-care ultrasound (POCUS) evaluations have the potential to identify interval development of clinically relevant findings, including gallbladder wall thickening, pericholecystic fluid, common bile duct dilation, and focal tenderness (sonographic Murphy's sign) (2). Despite this rationale, there is currently no prospective evidence supporting repeat POCUS examinations in ED patients with suspected cholecystitis.

Objectives

• To assess the role of a repeated biliary point-of-care ultrasound (POCUS) examination in ED patients with an initial US equivocal or negative for acute cholecystitis.
• To determine if a repeated biliary POCUS examination in the ED improves the diagnostic accuracy for acute cholecystitis.

The investigators hypothesize that a repeat biliary POCUS will improve diagnostic accuracy for acute cholecystitis in ED patients with an initially equivocal or negative ultrasound.

The investigators will conduct a prospective, single arm, interventional cohort study of adult ED patients presenting with right upper quadrant pain (RUQ) and clinical concern for acute cholecystitis. Patients will be eligible for enrollment if they demonstrate initial US that is negative or equivocal for acute cholecystitis, as well as ongoing symptoms prompting a general surgery consult or additional non-US advanced imaging. Consented study participants will undergo repeat biliary POCUS performed by credentialed ED physicians within 2-6 hours of their baseline US. Sonographic findings will be recorded with particular attention to interval changes to the gallbladder since the prior US. Additional data will be collected from the electronic medical record regarding clinical endpoints, including subsequent diagnoses of acute biliary pathology and the need for additional non-US imaging, consultation, or procedural intervention. The diagnostic accuracy and yield of repeat biliary POCUS will be calculated.

Inclusion criteria

• ≥ 18 years of age
• Presenting to the emergency department with abdominal pain with clinical concern for possible acute cholecystitis
• Initial biliary US interpreted as normal, equivocal or negative for acute cholecystitis
• 2-6 hours since initial biliary ultrasound with ongoing symptoms
• General surgery consult placed or additional non-ultrasound advanced imaging ordered
• Fluency in English or Spanish

Exclusion criteria

• < 18 years of age
• > 6 hours since initial biliary US
• Asymptomatic/resolved symptoms or pending discharge from the emergency department
• Initial ultrasound positive for acute cholecystitis or other findings to explain presenting symptoms
• Baseline ascites
• Prior cholecystectomy
• Unable or unwilling to provide consent
• Presenting to a facility other than study site emergency department
• Transferred patients from outside facilities