**7. Management of predisposing underlying conditions**

### **7.1 Nonsurgical management**

The detection and treatment of the underlying diseases that cause AP are as important as AP itself. Most gallstones that pass into the common bile duct advance to the intestines, and are excreted with feces. However, stones that cause obstructions to the pancreatic duct and/or biliary ducts may result in severe AP and/or cholangitis. ERCP is recommended within the first 24 hours for AP patients with stones detected as causing an obstruction. The removal of stones by via a sphincterotomy with ERCP prevents both severe AP and the cholangitis and future development of biliary AP. ERCP should be performed within the first 24 hours in AP patients due to gallstones accompanied by acute cholangitis. A papillotomy, or the surgical removal of stones, with ERCP reduces the severity of AP [48, 52, 96–98]. It has been reported that mortality decreases with early ERCP in patients with no cholangitis, with biliary duct obstructions, and with elevated liver function test scores. That said, it is unnecessary to perform ERCP within the first 24 hours on patients with no increase in liver function tests, with therapeutic ERCP recommended for such patients before or during the cholecystectomy. It is recommended that EUS and MRCP be performed prior to ERCP in patients without cholangitis or jaundice, but with suspected choledocholithiasis, pregnant women and patients on whom ERCP cannot be performed anatomically [47, 48, 52, 65, 99].

### **7.2 Surgical managment**

The removal of stones through the use of ERCP in patients without cholangitis can prevent the development of AP in the future, but it cannot prevent the development of biliary colic or cholecystitis. Accordingly, cholecystectomy is recommended prior to discharge in patients with mild AP and with gallstones [47, 48, 52, 65, 100–103]. Preoperative MRCP or EUS, or intraoperative cholangiography may be carried out for the selection of patients with common bile duct stones who need to be treated

through an operative bile duct exploration or endoscopic sphincterotomy during a cholecystectomy [48, 52, 99]. A cholecystectomy may be avoided in ineligible elderly patients (>80 years of age), particularly if a sphincterotomy has already been performed [48, 52, 96, 97]. A cholecystectomy should be performed in patients with gallbladder sludge and AP. In patients with necrotizing biliary AP, cholecystectomies should be delayed until the active inflammation subsides and fluid collections have resolved or stabilized. If collection takes longer than 6 weeks to resolve, the cholecystectomy should be delayed until it can be performed safely [47, 48, 52, 65]. Asymptomatic pseudocysts and pancreatic and/or extrapancreatic necrosis require no surgical intervention, regardless of the size, location and/or extension. In asymptomatic patients with infected necrosis, surgical, radiological and/or endoscopic drainage should be delayed for more than 4 weeks to allow for the liquefaction of the content and the development of a fibrous wall around the necrosis (WON). Minimally invasive necrosectomy methods are preferred in symptomatic patients with infected necrosis [47, 48, 52, 84, 87]. Percutaneous drainage and/or endoscopic drainage/debridement are minimally invasive alternatives to open surgery [104].

**Percutaneous CT-guided catheter drainage:** The procedure is performed under local anesthesia. Depending on the size and location of the necrosis, the catheter is placed under CT guidance. Irrigation with saline every several days after insertion [105, 106]. Although percutaneous catheter drainage was used for patients who are too unstable to undergo surgical debridement, approximately one third to one half of patients can be managed with this method alone [106, 107]. The only disadvantage of this method is the risk of persistent pancreatico-cutaneous fistula [108].

**Endoscopic debridement**: It is performed via transgastric or transduedonal [104, 105, 109]. Cystenterostomy is created using wire-guided balloon dilators. Mechanical debridement is performed using snares, baskets, and stone retrieval balloons. Following this, a stent is placed in the cavity. The flow of necrotic contents into the stomach or duodenum is provided [109]. Minimally invasive operative approaches are preferred to open surgical necrosectomy and given lower morbidity [110].
