The sensitivity of ultrasound in detecting choledocholithiasis compared to other imaging modalities
Amy Dumigan, Portsmouth Hospitals University Trust
Aim
The aim is to undertake an audit at a local teaching hospital, assessing the ultrasound accuracy of detecting choledocholithiasis compared to MRI.
The objectives are as follows:
1. Gather data from PACS
2. Retrospectively screen patients who have had an USS, MRCP and ERCP
3. Interpret results
4. Discuss findings
5. Conclusion and dissemination
Methods
The retrospective cross-sectional analysis identified patients between April 2022–March 2023 who underwent an ERCP examination on the RIS and were drawn from PACS. The researchers collected information of whether the individual had had an ultrasound examination and when this was conducted, an MRI examination and when this was conducted alongside the date and results. The inclusion criteria were patients who had an ERCP for removal of ductal stones. Exclusion criteria were patients who had received prior imaging elsewhere prior to the ERCP.
Results
The search results identified 168 patients who underwent an ERCP for removal of bile duct stones. 132 patients (78.6%) had a prior ultrasound examination, of which 45 patients (34.1%) were identified as having a diagnosis of choledocholithiasis. There were 86 patients (51.2%) who had an MRI prior to ERCP, whereby a total of 78 patients (90.7%) were confirmed to have choledocholithiasis. There were 75 patients (44.6%) who had an ultrasound followed by an MRI to ascertain a diagnosis of choledocholithiasis. The number of positive cases on ultrasound and MRI totaled 11 patients (14.6%), whilst 57 patients (76%) had a negative ultrasound diagnosis but a positive MRI diagnosis.
Conclusion
Ultrasound is the first line of investigation in assessing the gallbladder and bile ducts; however, the detection rate at a local teaching hospital is poor compared to MRI. The use of ultrasound is considered because of its accessibility, tolerability and relatively cheap cost, although the results of this audit suggest that patients would benefit from having an MRI when demonstrating symptoms of choledocholithiasis.