1.3 Pancreatic and Extra-Pancreatic Complications
In addition to the“plumbing”and“wiring”problems discussed above，many patients with CP experience pain due to intra-and extra-pancreatic complications of the disease.These are often easy to diagnose and treat and should always be considered when the patient is experiencing an exacerbation in pain symptoms.Among many，the most common are listed below.
1.3.1 Pseudocysts
As a relatively common complication，the estimated incidence of pancreatic pseudocysts is 20-40%（Boerma et al.2000；Andrén-Sandberg and Dervenis 2004）.Although lacking of long term follow-up studies，due to the chronic nature course of the disease，CP patients are at high risk of developing pseudocyst（Ammann et al.1984）.However，it is important to identify whether pseudocysts are asymptomatic or not according to the etiology，localization and size，the most influential factor of pain（Aghdassi et al.2008；Gouyon et al.1997）.
1.3.2 Duodenal and Bile Duct Obstruction(https://www.daowen.com)
The clinical presentation of duodenal and bile duct obstruction secondary to CP can be from asymptomatic to variable as postprandial/upper abdominal pain，early satiety，nausea and potential vomiting，fever，jaundice（Vijungco and Prinz 2003；Kalvaria et al.1989；Prinz et al.1985）.It is reported that without cholangitis bile duct obstruction does not cause pain and the relationship between“obstructive pain”and pain in patients with CP is still unclear（Kahl et al.2004）.
1.3.3 Peptic Ulcer
Previous studies have demonstrated that the prevalence of duodenal ulcer is high in patients with CP（ranges from 3.6 to 37.5%）and upper abdominal pain due to peptic ulcer can be mistaken as pancreatic pain（Lankisch et al.1993；Chebli et al.2002；Schulze et al.1983）.It is suggested that the high prevalence of peptic ulcer can be attributed to higher infection rate of Helicobacter pylori（Kalvaria et al.1989），increased gastric acid secretion（Saunders et al.1978；Piubello et al.1982），and decreased bicarbonate secretion and duodenal pH due to pancreatic exocrine insufficiency（Brock et al.2012）.Moreover，recurrent acute pancreatic attack may redistribute gastric and intestinal blood flow.
As peptic ulcer can also be asymptomatic and patients with CP are more likely to undergo an diagnostic or therapeutic upper gastrointestinal endoscopy，the high prevalence may also can be a result of a“detection bias”（Schulze et al.1983）.