David Madnick, MS4
The Study: Lahham, Shadi, et al. "Utility of common bile duct measurement in ED point of care ultrasound: A prospective study." The American Journal of Emergency Medicine, 36.6 (2018): 962-966
Clinical Question: Does measurement of CBD diameter help with diagnosis of biliary pathology in ED patients who are found to have gallstones by POCUS, but no other abnormal biliary findings by US or abnormal laboratory values?
Hypothesis: The incidence of concerning biliary pathology in patients with normal labs and cholelithiasis without gallbladder wall thickening (GWT), pericholecystic fluid (PCF), or sonographic murphy’s sign (SMS) is small and that measuring CBD in this setting is of little utility (i.e. yields no alteration of diagnosis or change in management)
Study Design:
· Prospective, observational study conducted at a single institution, UC Irvine (Level 1 Trauma Center w/ ED residency and US fellowship) between 11/2012 - 09/2014.
· Convenience sample of patients presenting with abdominal pain and concern for biliary pathology based on H&P
· Inclusion criteria à Patients who were at least 18 years old, able to provide consent in English or Spanish, and undergoing RUQ POCUS and serum laboratory testing as part of evaluation
· Exclusion criteria àPregnancy, incarceration, or failure to meet inclusion criteria
Protocol:
· US performed by residents, fellows, attending with various level of training and no study specific instruction. Physician was blinded to lab results while performing scan.
· Clinical data recorded by undergraduate ED research associates
o Serum labs collected included Alk-Phos, AST, ALT, T-Bili, WBC count with institutional cutoffs for abnormal values.
o If there was GWT, PCF or SMS, then the US was deemed abnormal.
· Further imaging, labs, or consultation left to discretion of treating clinician
· Final diagnosis was obtained either from ED physician note if discharged from ED or from hospital discharge summary if admitted.
· Patients were contacted 2 weeks after discharge in order to follow up if there was a change in diagnosis or if they represented to ED. If they could not be reached, then calls were placed monthly up until 1 year, at which point patient was excluded from study.
· Final diagnosis was classified as non-biliary or biliary. Biliary was further subdivided into uncomplicated cholelithiasis and complicated biliary pathology (acute cholecystitis, choledocholithiasis, cholangitis, and pancreatitis.
Primary Outcome:
· The number of cases of complicated biliary pathology in the setting of normal lab values and with POCUS demonstrating no GWT, PCF, or SMS.
Results: 167 patients were enrolled with 9 later being excluded for missing data or loss to follow up. Therefore 158 included in final analysis. Notable characteristics of the sample included 72% female, mean age 35, mean BMI 28. 82 (51.9%) patients were found to have presenting symptoms related to biliary pathology. Of these 82 patients, 39 (25%) had confirmed complicated biliary pathology. CBD dilation was visualized in 20 cases. Of these patients with CBD dilation only 2 lacked a concurrent lab abnormality or other POCUS abnormality. 1 of the 2 had uncomplicated cholelithiasis, and neither had complicated biliary pathology
Of the 39 patients diagnosed with complicated biliary pathology, abnormal labs, gallstones, other abnormal POCUS findings and dilated CBD were seen in 31 (79.5%), 18 (46.2%), 29 (74.4%) and 9 (23.7%) cases, respectively. Of the 158 total inclusions, there were 2 (1.3%) cases of complicated biliary pathology diagnosed in the absence of laboratory abnormalities, GWT, PCF and SMS. The diagnosis in each of these cases was choledocholithiasis, with one occurring in the absence of gallstones and both occurring in the absence of CBD dilation.
Main Conclusion:
Less than 2% of patients in this study were diagnosed with complicated biliary pathology when labs were normal and there were no concerning POCUS findings beyond cholelithiasis. This data supports the hypothesis that measurement of the CBD is unlikely to help with evaluation of patient with suspected biliary pathology.
Final Thoughts:
This was the first prospective study to address this issue. It provided convincing data that CBD measurement is of little utility in the setting of normal labs and POCUS for identification of complicated biliary pathology. Limitations of the study included convenience sampling, single center study, and varying experience level of sonographers. Average BMI was 28 and may not be generalizable to patients with higher BMI.