Poster (15W169)

Correlation between MRCP positive and ERCP positive studies for biliary tree stones

Author(s)

R. Stack, C. McGarvey, V. Parihar, N. Breslin, D. McNamara, H. O’Connor, I. Cretu, B. Ryan

Department(s)/Institutions

AMNCH, Tallaght, Dubin 24.

Introduction

Choledocholithiais is a common condition. Timely ERCP is the treatment of choice but it is not without risk. Nowadays ERCP is usually performed following positive findings on non invasive imaging such as MRCP or ultrasound. However not infrequently patients who have been diagnosed with choledocholithiasis on imaging and who subsequently undergo ERCP, do not have a calculus at time of procedure, likely due to spontaneous passage of stones.

Aims/Background

Patients who undergo a normal ERCP are exposed to unnecessary risk. Better identification of patients who are likely to have already passed a stone should be common practice. This patient group should undergo an EUS if available, prior to ERCP. The aim of this study was to try to identify factors that might predict a normal exam.

Method

So far we have identified 179 patients who underwent ERCP at our institution for either confirmed or suspected choledocholithiasis on imaging (ultrasound, MRCP or CT). Patients who had positive findings on imaging but who had no calculi on ERCP were categorised based on (1) time lag between imaging and ERCP, (2) improving LFTs or not and (3) size of stones.

Results

The study cohort comprised n=110(61.5%) AMNCH and n=69(38.5%); external institute patients [median age – 68; male gender n=59 (33.0%)]. 38 patients (21.2%) in total had no confirmed stone on ERCP. Of these patients, 13 (34.2%) were referred from AMNCH and 25 (65.7%) were external referrals. The time delay for the AMNCH patients between imaging and ERCP were as follows: n=6 – 30 days. LFTs at time of imaging and ERCP for AMNCH patients identified 9 out of 13 patients had a downward trending profile before intervention. Further analysis of the external subgroup and of stone size is in progress.

Conclusions

The majority of negative ERCP findings were from the external institution cohort. Indeed 25/69 (36%) of this group had negative ERCPs as opposed to 13/110 (11.8%) of in-house procedures. This disproportion may be attributable to delay in access to ERCP but other factors may also play a role. In the AMNCH cohort with negative ERCP, there was strong biochemical evidence to suggest resolution of obstruction prior to intervention. We propose that patients who have a substantial delay to ERCP or who have improving LFTs prior to intervention should undergo an EUS prior to ERCP to re-assess the CBD and thus avoid unnecessary intervention.

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