Post written by Michael Lajin, MD, from Sharp HealthCare, San Diego, California, USA.

A 55-year-old man with chronic calcific pancreatitis presented with abdominal pain and 12-pound weight loss. Abdominal CT and MRCP showed a large burden of calcified obstructive pancreatic duct (PD) stones above the papilla resulting in upstream PD dilatation measuring 19 mm. 

We discussed the options including surgical, endoscopic, and referral for extracorporeal shockwave lithotripsy (unavailable at our institution). The patient elected to proceed with endoscopic treatment. 

Owing to the size of stones compacted above the papilla, we decided to perform primary EUS-guided pancreatic drainage (EUS-PD) given the high chance of a failed ERCP in this setting. An electrocautery-enhanced lumen-apposing metal stent (LAMS) was used because of sufficient dilatation of the PD, allowing safe deployment and the minuscule distance separating the PD from the GI wall. 

Using electrocautery, we deployed a LAMS (10 x 10 mm) with a freehand technique, attaining pancreaticoduodenostomy. Decompression of the PD was achieved, resulting in substantial pain relief. Six weeks later, the LAMS was removed. A pediatric endoscope (GIF-XP190N/5-mm outer diameter; Olympus, Tokyo, Japan) was advanced through the fistula inside the PD toward the head of the pancreas. Large impacted stones were fragmented with laser lithotripsy. 

Subsequently, after clearing the stones impacted above the major papilla, we were able to access the PD through the major papilla. Pancreatoscopy with laser lithotripsy was resumed through the major papilla, gaining duct clearance.    

EUS-PD is typically wire-guided creation/dilation of a tract followed by deployment of transgastric or transduodenal plastic stents. This technique carries inherent risks such as leaks, bleeding, stent dysfunction, and migration.

A LAMS possesses favorable characteristics for EUS-PD:

• The stent deployment mechanism avoids antecedent tract creation/dilation. In addition, the LAMS is fully covered. These features decrease the risk of leakage.
• The dumbbell shape of the LAMS lowers the risk of stent migration.
• The LAMS creates a wider fistula to facilitate future pancreatoscopy and stone extraction.
• Although fully covered, the LAMS does not block the side branches of the PD.
• The LAMS electrocautery-enhanced delivery system allows the stent catheter to penetrate a fibrous PD wall.

These features make LAMSs an enticing choice to perform EUS-PD as long as the PD is sufficiently dilated to enable safe deployment of the stent.

Although this case report demonstrates the feasibility of performing EUS-PD as a primary approach to treating difficult pancreatolithiasis in experienced centers, more data are needed before recommending wide-range adoption of this approach. Using LAMSs to perform EUS-PD might offer several advantages over the traditional tract creation and dilation technique such as less risk of migration and leak. Nevertheless, this approach is only feasible when the PD dilatation is sufficient enough to allow safe deployment of the stent.

CT image of a lumen-apposing metal stent at the pancreaticoduodenostomy (yellow arrow).

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