Background: The prevalence of chronic pancreatitis [CP] in chronic abdominal pain [CAP] patients is varied and inconclusive. The clinical predictors of having CP in CAP have not been identified.

Objective: To identify the prevalence of CP by using endoscopic ultrasonography [EUS] in patients with CAP with negative endoscopy and cross-sectional imaging studies.

Materials and Methods: Eligible patients with CAP for more than three months, having negative endoscopic and cross-sectional imaging results, did not meet Rome III criteria of functional gastrointestinal disorders, and underwent EUS were included. CP was diagnosed by EUS using Rosemont criteria. Prevalence of CP was calculated, and logistic regression analysis was performed to identify independent factors associated with the presence of CP.

Results: Of the 92 patients with CAP, 18 had CP and the prevalence was 19.6%. Two factors were found to be independent factors associated with the presence of CP, referred pain to back (OR = 3.23, p = 0.040) and absence of comorbidity (OR = 5.06, p = 0.042).

Conclusion: CP was found in one-fifth of patients with CAP and negative endoscopy and imaging study. Referred pain to back and absence of comorbidity predicted the presence of CP.

Keywords: Abdominal pain, Chronic pancreatitis, Endoscopic ultrasonography, Pain, Pancreatic pain