**4. MPD strictures**

In cases of stenosis in the MPD, possible malignancy should be ruled out using high-quality pancreatic CT or magnetic resonance cholangiopancreatography (MRCP). Brush cytology should be performed, and biopsy should be performed if necessary. A dominant MPD stricture is characterized by upstream MPD dilatation of ≥6 mm, prevention of contrast medium outflow alongside a 6-Fr catheter inserted upstream from the stricture, and abdominal pain during continuous infusion of a nasopancreatic catheter inserted upstream from the stricture with 1 L saline for 12–24 h. Technical success was defined as stent insertion across the dominant MPD stricture. This management aims to decompress the MPD, improves pain, dilates the stricture, and allows stone clearance after ESWL. A prospective non-randomized study on patients with dominant strictures reported less pain in the temporary pancreatic stenting group during a 5-year follow-up (15% vs. 50%) [27]. These strictures

### *Endoscopic Management of Chronic Pancreatitis DOI: http://dx.doi.org/10.5772/intechopen.107321*

are generally single in >80% of the patients. Temporary single pancreatic stents provide 9–50% resolution and 67.5% pain relief [28, 29].

A refractory stricture was defined as symptomatic persistent dominant strictures or relapse after 1 year of single pancreatic stenting. Refractory strictures can be treated with multiple side-by-side stents, self-expanding metallic stents (SEMSs), or surgery. Temporary insertion of multiple side-by-side stents provided high stricture resolution and pain relief of 89.5% and 77.1%, respectively, during a 9.5-year follow-up [30]. SEMS insertion also achieved high pain improvement in 37–88% of all patients in a follow-up of 3–4 years [31]. Unlike SEMS, uncovered and partially covered stents are not suggested for migration risk.

Pancreatic sphincterotomy is mainly suggested if biliary drainage is necessary to facilitate MPD cannulation. Sphincterotomy is not mandatory for pancreatic stenting. Pancreatic stenting is performed mostly after ESWL if there is a pancreatic stone. The technical success of a single pancreatic stent is approximately 92%. In 18 series of 811 patients, the mean stenting duration was 10.6 months [32].

Multiple side-by-side pancreatic stents are another treatment option for refractory cases. Different stent designs are used: straight, winged, and s-shaped, with side holes. Stents with large side holes are suggested to have a low occlusion risk. The stent diameter is also critical. Patients with CP with ≤8.5-Fr pancreatic stents are 3.2 times more often hospitalized with abdominal pain than patients with CP with a 10-Fr pancreatic stent [33, 34].

The "on-demand" stent exchange strategy is based on clinical and laboratory evaluation at 6-month intervals, such as secretin-enhanced (S)-MRCP, abdominal ultrasound, abdominal radiography, and blood/urinary lipase analysis. However, this policy, in four series of 288 patients, reported a 5.2% rate of pancreatic sepsis [35]. Nevertheless, 12 series of 521 patients in whom the pancreatic stent was changed every 3 months regularly reported no septic complications [36].

Mild pancreatitis and worsening pancreatic pain are the most common shortterm complications after plastic stenting, followed by sepsis, cholangitis, and post-sphincterotomy bleeding. During follow-up, proximal and distal stent migration was reported in 2.7% and 3.6% of the cases, respectively. Stent-induced ductal lesions were observed in 18% of the cases, and the mortality rate was 0.4% (7/1620). Complications after SEMS insertion include migration (15–46%), de novo strictures (16–27%), severe pain (7–20%), and stent removal (15%).

EUS-guided access and drainage is another treatment modality for patients with symptomatic MPD obstruction and failed transpapillary drainage. After puncturing the MPD through the gastric or duodenal wall, transpapillary drainage can be facilitated with a guidewire (rendezvous technique)**,** transmural drainage with a plastic stent**,** or a fully covered SEMS (FCSEMS) can be used to achieve successful pain relief. This is one of the most challenging EUS-guided therapies. Failed EUS-guided access and drainage occur in 10% of cases, and complications such as severe pancreatitis, perforation, bleeding, and hematoma can occur [37]. This procedure is suggested only in tertiary centers after multidisciplinary discussion.
