The utility of an under-distended gallbladder on ultrasound in ruling out acute cholecystitis

Purpose To study the association between gallbladder dimensions and acute cholecystitis and to define a sensitive cutoff for excluding the disease. Materials and methods 456 consecutive patients with an abdominal ultrasound performed for right upper quadrant pain, from 1/2019 to 4/2019, were retrospectively collected. Length and width of the gallbladder were measured by a blinded radiology fellow. Patient charts were examined for prospective sonographic findings, clinical data, and pathology from subsequent cholecystectomy or at least 1 month of follow-up with symptom resolution. Univariable and multivariable logistic regression analysis were conducted to define the association of gallbladder dimensions and other sonographic and clinical variables with acute cholecystitis. Optimal and sensitive cutoffs of gallbladder widths were defined. The determined sensitive cutoff was validated with a separate cohort of 501 consecutive patients. Results 319 patients (median age 48 ± 19 years) including 11%, 19%, and 70% with acute, chronic, and no cholecystitis were included in the experimental cohort, respectively, and 298 patients (median age 50 ± 19 years) including 10%, 12%, and 79% with acute, chronic, and no cholecystitis were included in the validation cohort, respectively. Of all sonographic findings and clinical data, gallbladder width produced the best univariate ROC curve with an AUC of 0.91 (Odds ratio 5.1, 95% CI 3.1–8.5, p < 0.001). 2.2 cm was the gallbladder width cutoff below which there were no cases of acute cholecystitis in the experimental cohort. Multivariable logistic regression analysis using sonographic findings only produced an ROC curve with an AUC of 0.94. Applying the 2.2 cm cutoff in the validation cohort resulted in 100% sensitivity. Conclusion Lack of gallbladder distention, defined as a width less than 2.2 cm, has potential to serve as a highly sensitive sign for exclusion of acute cholecystitis, regardless of additional sonographic findings and clinical data.