Association of biliary distention with a diagnosis of acute cholecystitis

Gallbladder distention has been described in radiology literature but its value on point-of-care ultrasound (PoCUS) performed by emergency physicians is unclear. We sought to determine the test characteristics of gallbladder distention on PoCUS for cholecystitis (acute or chronic), and secondarily whether distention was associated with an obstructing stone-in-neck (SIN), acute cholecystitis on subsequent pathology report, and longer cholecystectomy operative times.

This was a dual-site retrospective cohort study of all Emergency Department (ED) patients that underwent diagnostic biliary PoCUS and were subsequently admitted from 11/1/2020 to 10/31/2022. Patients with pregnancy, liver failure, ascites, hepatobiliary cancer, prior cholecystectomy, or known cholecystitis were excluded. Gallbladder distention was defined as a width ≥4 cm or a length ≥10 cm. Saved ultrasound images were reviewed by three independent reviewers who obtained measurements during the review. Test characteristics, Cohen's kappa (κ), and strength of association between distention and our variables (acute cholecystitis on pathology report and SIN on PoCUS) were calculated using a Chi Square analysis, where intervention (cholecystectomy, percutaneous cholecystostomy, or intravenous antibiotics) was used as the reference standard for AC. A one-tail two sample t-test was calculated for mean operative times.

Of 280 admitted patients who underwent ED biliary PoCUS, 53 were excluded, and 227 were analyzed. Of the 227 patients, 113 (49.8%) had cholecystitis according to our reference standard, and 68 (30.0%) had distention on PoCUS: 32 distended by both width and length, 16 distended by width alone, and 20 distended by length alone. Agreement between investigators was substantial for width (κ 0.630) and length (κ 0.676). Distention was 85.09% (95% CI 77.20-91.07%) specific and 45.1% (95% CI 35.8-54.8%) sensitive for cholecystitis. There was an association between distention and SIN; odds ratio (OR) 2.76 (95% CI 1.54-4.97). Distention of both length and width was associated with acute over chronic cholecystitis; OR 4.32 (95% CI 1.42-13.14). Among patients with acute cholecystitis, mean operative times were 114 min in patients with distention and 89 min in patients without distention (p = 0.03).

Gallbladder distention on PoCUS was specific for cholecystitis (acute or chronic), and associated with SIN, acute cholecystitis on subsequent pathology report, and longer cholecystectomy operative times. Measurement of gallbladder dimensions as part of the assessment of cholecystitis may be advantageous.