E. Wiesner1,2, L. Martin1,2, W. Peche1,2, J. Langell1,2 1VA Salt Lake City Health Care System,Center Of Innovation,Salt Lake City, UT, USA 2University Of Utah,Department Of Surgery,Salt Lake City, UT, USA
Introduction: The use of gallbladder ejection fraction obtained by hepatobiliary iminodiacetic acid scan to diagnose Biliary Dyskinesia (BD) continues to be controversial. Cholescintigraphy or hepatobiliary iminodiacetic acid (HIDA) scan is a nuclear medicine imaging study that allows for the calculation of gallbladder ejection fraction (GBEF). Patients with a clinical presentation consistent with BD and a low GBEF (<35%) are considered appropriate candidates for therapeutic cholecystectomy. False positive HIDA-based GBEFs have been associated with the concomitant use of narcotic medications. Narcotic analgesics are thought to reduce biliary smooth muscle motility and are typically therefore discontinued prior to conducting the HIDA scan. In this study we looked at the impact of narcotic use on HIDA scan-based GBEF in patients with suspected BD.
Methods: We queried the Veterans Healthcare Administration National Corporate Data Warehouse from January 2005 to July 2016 for patients who underwent more than one HIDA scan. Patients undergoing HIDA for a suspected diagnosis of BD were included. Radiology reports were reviewed and the GBEF for each study was abstracted. We further categorized patients with abnormal GBEFs into those receiving concomitant narcotic analgesics during their initial HIDA scan and on subsequent HIDA scan. A comparison was conducted to determine the impact of narcotic use on the reported GBEF in these populations.
Results: We identified 546 patients who underwent more than one HIDA scan for suspected BD during the study period. Thirty-three percent (181) of all patients had an abnormal GBEF (average GBEF=17%) on their initial study. Of these, 34 patients (19%) were on narcotic analgesics at the time of their initial HIDA scan (average GBEF=16%). Of the 181 patients with a low GBEF, 45% were found to have a normal GBEF on repeat scan (average GBEF=41% and average time between studies 26.5 months), where as 100% of patients on narcotic analgesics demonstrated a normal GBEF on subsequent HIDA scan (average GBEF=74% and average time between studies 29.9 months) (p-value=0.005). This finding was independent of continued narcotic use (26% of patients).
Conclusion: In this study, all patients who met diagnostic criteria for BD based on a low HIDA scan-based GBEF and were on narcotic analgesics at the time of the initial HIDA scan demonstrated a normal GBEF on subsequent scan. This finding was independent of chronic long-term narcotic analgesic use. Of the 26% of patients who remained on narcotic analgesics at the time of repeat scan, 100% were found to have a normal GBEF. Although this study supports the discontinuation of narcotic analgesics prior to conducting a HIDA scan when possible, it also suggests that there may still be utility in conducting the repeat scan when patients who are chronic users of narcotics are unable to come off these medications. Further studies will need to be conducted to confirm these findings and determine if the effect of narcotic analgesics on biliary smooth muscle motility is lost with chronic narcotic exposure.