Published online Jun 16, 2022. doi: 10.4253/wjge.v14.i6.376
Peer-review started: January 28, 2022
First decision: April 10, 2022
Revised: April 23, 2022
Accepted: May 22, 2022
Article in press: May 22, 2022
Published online: June 16, 2022
Idiopathic acute pancreatitis (IAP) is a common condition and represents a diagnostic challenge because up to 20% of patients with IAP have recurrent episodes and may evolve to chronic pancreatitis. Endoscopic ultrasound (EUS) is highly effective in the etiological diagnosis of IAP, even after failure of a previous imaging technique. A significant proportion of AP remains idiopathic even after multiple imaging techniques, mainly including abdominal US, contrast-enhanced computed tomography (CECT) and magnetic resonance cholangiopancreatography (MRCP).
The role of EUS in IAP has been established by multiple studies, including meta-analyses. However, limited data are currently available about the diagnostic gain of EUS in cases of failure of multiple previous imaging techniques.
The primary aim of the study was to evaluate the diagnostic gain of EUS after failure of US, CECT and MRCP and particularly after different combination of these techniques. The secondary aims were to assess the overall EUS diagnostic yield in IAP, to associate the baseline clinical features with the specific IAP diagnosis and to analyze the frequency and types of AP recurrence during the follow-up.
We performed a retrospective, single-center study. We enrolled all consecutive adult patients undergoing EUS for IAP over a 3-year period at the Ospedale Maggiore of Cremona. IAP was defined when a clear etiology could not be identified after a thorough medical history, complete blood tests and after performing at least one US, CECT or MRCP exam. The EUS diagnostic gain was calculated as the percentage of additional diagnoses obtained at EUS over the total number of patients undergoing US, CECT and/or MRCP.
Overall EUS diagnostic yield was 79%, with 21% of AP remaining idiopathic. This percentage is in line with the current literature. Gallstone disease and chronic pancreatitis were the most frequent diagnoses (20% and 31%, respectively). The EUS diagnostic gain over the associations of CECT + MRCP and US + CECT + MRCP was 63% and 68%, respectively. This is a relevant result that confirms the superiority of EUS in the etiological diagnosis of IAP, particularly in detecting microlithiasis and early signs of chronic pancreatitis. In patients without a previous cholecystectomy and with a final diagnosis of biliary pancreatitis, higher baseline median values of liver enzymes were found. Moreover, in patients with recurrent pancreatitis, chronic pancreatitis was the diagnosis in 82% of cases. These results suggest a high efficacy of EUS in the etiological diagnosis of IAP in patients without previous cholecystectomy and with recurrent pancreatitis. During a median follow-up of 31.5 mo, an additional episode of pancreatitis was observed in 3.7% of patients.
EUS has a high diagnostic yield in IAP. About two-thirds of patients with IAP without etiological diagnosis with various combinations of US, CECT and MRCP received a diagnosis at EUS. This finding confirms the superiority of EUS over these techniques and proposes EUS as the investigation of first choice in all suitable patients. EUS shows the highest diagnostic gain in the setting of increased liver enzymes with no previous cholecystectomy and in the setting of recurrent pancreatitis.
The role of EUS in the etiological diagnosis of IAP has been established by multiple studies including meta-analyses. Our study provided additional data supporting the high diagnostic gain of EUS in cases of failure of multiple previous imaging techniques. Future research should focus on the prognostic value of EUS in the setting of IAP, since patient management may change following the EUS diagnosis. Large multicentric and prospective studies addressing this issue are needed.