Stone density can predict the number of ESWL treatments needed in patients with pancreatic duct calculi.

Objectives: Extracorporeal shock wave lithotripsy (ESWL) with endotherapy (ET) is the first-line treatment in patients with chronic pancreatitis (CP) and main pancreatic duct stone (PDS). Our study aimed to evaluate factors that predict the outcome of ESWL in CP patients with PDS.

Methods: We retrospectively analyzed data of 166 patients with CP and radiopaque PDS. Computed tomography (CT) images were evaluated for stone density, stone size, main pancreatic duct (MPD) size, and skin-to-stone distance (SSD). Long-term pain relief results were determined telephone interview in 100 patients.

Results: Mean stone density (MSD) > 1336 HU predicted the need to perform more than one ESWL session (odds ratio [OR]: 1.002; 95% confidence interval [CI]: 1.001 to 1.003;  = 0.002), cut-off 1336 HU yielding 71% sensitivity and 65% specificity. Denser stones required more ESWL and following ET, with ≥4 ET sessions resulting in better technical success. (OR: 3.222; 95% CI: 1.240 to 8.371;  = 0.016). Overall technical success (complete stone fragmentation in ESWL or placing a stent past the stone in ET) rate was 81.3%. Clinical success (complete or partial pain relief at the end of the treatments) rate was 83.7% and remained at the same level also in the long-term follow-up (median 5.5 years). Stone size, MPD size, or SSD were not associated with any of the study outcomes.

Conclusions: Higher MSD than 1336 HU predicts the need for more than one ESWL and ET sessions to fragment the stone and clear the duct, but when successful the long-term result is favorable.