**2. Acute pancreatitis**

### **2.1 Endoscopic management of acute biliary pancreatitis**

In Western countries, gallstone represents the first cause of AP, accounting for almost half of the cases, affecting middle-aged people, especially women [5].

### *Endoscopic Management of Acute and Chronic Pancreatitis DOI: http://dx.doi.org/10.5772/intechopen.105930*

The pathogenic mechanism by which gallstones determine AP is a temporary obstruction of the main pancreatic duct. Biliary AP should be suspected in presence of elevated liver function tests (LFTs) within 24–48 hours of the onset of symptoms, with alanine aminotransferase (ALT) >3× upper limit of normal having a 95% positive predictive value for AP. Nevertheless, its negative predictive value is only 50%. Aspartate aminotransferase (AST), alkaline phosphatase (ALP), and bilirubin have both low sensitivity and negative predictive value [6].

Most patients with biliary AP have a mild-to-moderate disease course, benefiting from conservative management. The majority of common bile duct (CBD) stones causing biliary AP are small (≤5 mm), and their spontaneous passage into the duodenum occur in 80% of cases, with no need for endoscopic intervention. Magnetic resonance imaging (MRI) or EUS is requested to exclude the presence of CBD stones, prior to ERCP. While the utility of EUS in identifying the cause of AP after the acute attack is well established, data regarding the role of EUS during hospitalization for AP are limited. In presence of AP edema of the duodenal wall, pancreatic and peripancreatic inflammation, fluid or necrotic collections make difficult the study of pancreatic parenchyma, gallbladder, and biliary tree. Thus, EUS aimed to identification of small pancreatic cancer or early changes of chronic pancreatitis must be avoided. On the contrary, EUS could be useful in the diagnosis of choledocholithiasis due to its higher sensitivity compared to MRCP for small CBD stones (<5 mm). In those patients with AP and intermediate risk of CBD stones, EUS may avoid unnecessary ERCP [7, 8].

Guidelines recommend against urgent ERCP (within 48 hours) in AP, especially in case of severe disease, unless in presence of cholangitis or ongoing/worsening biliary obstruction. However, if choledocholithiasis is confirmed, ERCP with biliary sphincterotomy and stones extraction should be performed during the index hospitalization, in order to reduce the rate of readmission for a new episode of biliary AP. If CBD has been completely cleared from stones during ERCP, biliary stenting is not routinely indicated before cholecystectomy. In cases of acute suppurative cholangitis, when smaller contrast injection and shorter procedural time, due to bad clinical status of the patient, are required, placement of a biliary stent can ensure adequate drainage, waiting to be able to perform biliary stone extraction. In patients with large bile duct stones, endoscopic large balloon dilation after sphincterotomy is suggested [9].

In case of mild biliary AP, same-admission cholecystectomy or early cholecystectomy (within 2–4 weeks from the onset of AP) is recommended, to avoid recurrence of AP [10].
