Original Contribution
Utility of common bile duct measurement in ED point of care ultrasound: A prospective study

https://doi.org/10.1016/j.ajem.2017.10.064Get rights and content

Abstract

Background

Measurement of the common bile duct (CBD) is considered a fundamental component of biliary point-of-care ultrasound (POCUS), but can be technically challenging.

Objective

The primary objective of this study was to determine whether CBD diameter contributes to the diagnosis of complicated biliary pathology in emergency department (ED) patients with normal laboratory values and no abnormal biliary POCUS findings aside from cholelithiasis.

Methods

We performed a prospective, observational study of adult ED patients undergoing POCUS of the right upper quadrant (RUQ) and serum laboratory studies for suspected biliary pathology. The primary outcome was complicated biliary pathology occurring in the setting of normal laboratory values and a POCUS demonstrating the absence of gallbladder wall thickening (GWT), pericholecystic fluid (PCF) and sonographic Murphy's sign (SMS). The association between CBD dilation and complicated biliary pathology was assessed using logistic regression to control for other factors, including laboratory findings, cholelithiasis and other sonographic abnormalities.

Results

A total of 158 patients were included in the study. 76 (48.1%) received non-biliary diagnoses and 82 (51.9%) were diagnosed with biliary pathology. Complicated biliary pathology was diagnosed in 39 patients. Sensitivity of CBD dilation for complicated biliary pathology was 23.7% and specificity was 77.9%.

Conclusion

Of patients diagnosed with biliary pathology, none had isolated CBD dilatation. In the absence of abnormal laboratory values and GWT, PCF or SMS on POCUS, obtaining a CBD measurement is unlikely to contribute to the evaluation of this patient population.

Introduction

Biliary disease is common in the United States. Approximately 20 million patients present to the emergency department (ED) annually with complaints related to cholelithiasis [1], [2], [3], [4]. Laboratory serum testing is routinely performed, but is generally not sufficient to differentiate between specific biliary diagnoses [5], [6], [7]. The use of ultrasound (US) is instrumental in clarifying the diagnosis and guiding treatment [8], [9], [10]. In general, uncomplicated symptomatic cholelithiasis can be managed expectantly with symptom control and outpatient referral to surgery. Conversely, complicated biliary pathology, such as acute cholecystitis, choledocholithiasis and ascending cholangitis, warrants more urgent consultation and hospitalization for further diagnostic study or definitive treatment.

Several studies have shown that point of care ultrasound (POCUS) can lead to accurate diagnosis of biliary pathology and expedite patient care [1], [11], [12], [13]. POCUS of the right upper quadrant (RUQ) typically assesses for the presence of gallstones, gallbladder wall thickening, pericholecystic fluid (PCF), sonographic Murphy's sign (SMS) and common bile duct (CBD) dilatation [14], [15]. Despite being considered a fundamental element of RUQ POCUS, proper identification and accurate measurement of the CBD can prove technically challenging [3], [16]. In the face of uncertain CBD identification, the ability of normal laboratory tests and an otherwise normal RUQ US to exclude complicated biliary pathology would be of great clinical benefit. Prior research has suggested that CBD diameter yields limited unique clinical information in patients with cholecystitis and choledocholithiasis with normal laboratory values; however, there are no prospective studies to date that have confirmed these findings [17], [18], [19], [20], [21].

We sought to prospectively assess the importance of sonographic CBD measurement in evaluating patients for biliary pathology, particularly in the setting of normal laboratory values and an otherwise unremarkable biliary US. We predict that the incidence of concerning biliary pathology in patients with normal laboratory values and no significant ultrasound finding beyond uncomplicated cholelithiasis is small and measurement of the CBD in this setting is unlikely to alter diagnosis or change management. The primary objective of this study was to determine if there is any utility to measure a CBD diameter in patients with normal laboratory values and a RUQ POCUS without GWT, PCF and SMS for the diagnosis of complicated biliary pathology in ED patients.

Section snippets

Study design

We performed a prospective, observational study of adult ED patients receiving serum laboratory studies and undergoing POCUS of the right upper quadrant (RUQ) for evaluation of potential biliary pathology. Final diagnoses were assessed with respect to POCUS findings and laboratory results to determine the relative contribution of CBD measurement.

Study setting and population

The study was performed at an academic level 1 trauma center with an emergency medicine residency and an emergency ultrasound fellowship program. The

Characteristics of study subjects

A total of 167 patients were enrolled. After excluding 9 cases for missing data, loss to follow up or duplicate enrollment, 158 patients were included in the final analysis. Females comprised 114 (72.2%) of the inclusion cohort. The median age and BMI was 35 years (Interquartile Range (IQR) 28–46.5, range 18–87) and 28 (IQR 25.6–32.8), respectively.

Of the 158 included patients, 76 (48.1%) received non-biliary diagnoses and 82 (51.9%) were diagnosed with biliary pathology. Isolated uncomplicated

Discussion

Our primary results demonstrate < 2% of ED patients diagnosed with complicated biliary pathology failed to simultaneously exhibit abnormal laboratory studies or other concerning findings on POCUS beyond uncomplicated cholelithiasis. Thus, the absence of abnormal laboratory values or other sonographic findings suggests that measurement of the CBD is unlikely to contribute to the evaluation of the patient with suspected biliary pathology. These results are similar to previously published

Limitations

There are several limitations to the study. Patients were enrolled as a convenience sample of patients at a single, academic ED. Patients who did not speak English or Spanish were excluded. The experience level of the physician sonographers was variable and POCUS findings, including CBD measurements, were not validated by an expert sonographer or radiologist. While these facts tend to reflect a real-world application of POCUS in the evaluation of potential biliary pathology, the study findings

Conclusion

In the absence of abnormal laboratory values or other sonographic findings, measurement of the CBD is unlikely to contribute to the evaluation of the patient with suspected complicated biliary pathology.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Funding sources/disclosures

Dr. J Christian Fox receives stock options from Sonosim for consulting. However, no Sonosim products were used in this research project.

Acknowledgments

UC Irvine Health Department of Emergency Medicine, UC Irvine School of Medicine.

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