Accuracy of Emergency Medicine resident-performed bedside ultrasound in diagnosing cholelithiasis: a retrospective study
Background: Abdominal pain secondary to cholelithiasis is one of the most frequent causes of emergency room visits. Point-of-care ultrasound has the potential to help in the quick assessment of the presence of cholelithiasis speeding up the management of patients. This study aims to determine the accuracy of emergency medicine (EM) resident-conducted bedside/point-of-care ultrasonography to detect cholelithiasis in patients with suspected biliary colic.
Methods: This is a retrospective cohort study to evaluate the ability of emergency medicine residents to diagnose cholelithiasis by ultrasound in the Emergency Department (ED) of the St. Luke’s Medical Center – Quezon City. Ultrasound record sheets of ED patients with a chief complaint of epigastric and right upper quadrant abdominal pain from January 2015 to August 2015 were collated and reviewed to determine the ability of emergency medicine residents to diagnose cholelithiasis by focused gallbladder ultrasound. Emergency medicine resident-performed gallbladder ultrasound was compared to formal radiology department ultrasound diagnosis to determine its accuracy.
Results: Of the 97ultrasound record sheets collected within the study period, 45 patients (47%) did not undergo formal radiologic ultrasound while 50 (53%) of the suspected biliary colic patients underwent confirmatory radiology department ultrasonography. Of these patients, 30 (58%) yielded positive diagnosis of gallstones, 16 (30%)had false positive results, 2 (4%) had true negative results and 4 (8%)revealed sonographic findings other than gallstones such as biliary sludge and gallbladder polyps. Utilizing formal radiologic interpretation as the gold standard, emergency medicine resident- conducted gallbladder ultrasound was determined to be 100% sensitive (95% CI,88.43% to 100.00%) and 11% specific (95% CI, 1.8 to 34.71%), while positive predictive value (PPV) was 65% (49 to 78%) and the negative predictive value at 100% (15 to 100%).
Conclusion: Bedside or point-of-care gallbladder ultrasound performed by emergency medicine residents to diagnose cholelithiasis in the emergency department is highly sensitive but not specific. Additionally, it also has a high negative predictive value with a low positive predictive value.