**2. Timing and role of ERCP in acute biliary pancreatitis**

Acute biliary pancreatitis results from transient obstruction of the common bile duct by stones. Majority of the stones spontaneously pass into the duodenum followed by resolution of the acute pancreatitis [2]. In a few of the patients, persistent choledocholithiasis can lead to pancreatic duct and/or biliary tree obstruction resulting into severe/persistent pancreatitis and/or cholangitis with resolution and complication risk reduction on removal of the offending stones [3].

Stone can be extracted during ERCP by either balloon catheters or dormia stone extraction baskets after either endoscopic sphincterotomy (papillotomy) and/or endoscopic papillary balloon dilatation (sphincteroplasty). Papillary balloon dilatation is however not routinely recommended due to a lower technical success for stone clearance and a presumed increased risk of pancreatitis. It can however be considered in patients with coagulopathies or altered anatomy with smaller (<8 mm) stones [4]. Endoscopic sphincterotomy with stone extraction is associated with 80–90% success rate in common bile duct (CBD) stones treatment. In cases of irretrievable biliary stones, temporary biliary plastic or metallic stents can be placed to relieve the obstruction followed by a second attempt at stone removal combined with either mechanical or extracorporeal shock wave lithotripsy (ESWL). Failure of ERCP, EUS mechanical or ESWL ultimately means surgical intervention which can be open or laparoscopic cholecystectomy with choledocholithotomy to remove the CBD stones done during CBD exploration. For cases of ERCP with stenting, the stents may however, be associated with complications such as cholangitis and so should be removed or exchanged every 3–6 months. Definitive stenting is recommended in the elderly with a limited life expectancy and co-morbidities with caution due to the high rates of complications such as cholangitis with associated high mortality [4].

There is consensus among different meta-analyses and guidelines on the role and timing of early ERCP with endoscopic sphincterotomy (ES) in case of acute biliary pancreatitis in the presence of cholangitis and/or persistent cholestasis. However there is obvious lack of agreement on the role and timing of ERCP in mild or severe predicted acute biliary pancreatitis in the absence of cholangitis or persistent cholestasis [5]. Neoptolemus J.P. et al. [6] conducted a randomized controlled trial involving 121 patients with suspected biliary acute pancreatitis using the modified Glasgow system for severity stratification. Early ERCP done within 72 hours plus Endoscopic sphincterotomy for those with common bile duct stones was associated with reduction in complications and shorter hospital stay significantly among those with severe acute pancreatitis when compared with those on conventional treatment. The reduction in complications was still noticed even after excluding those with associated cholangitis. However, no difference in mortality was noted. Another randomized control trial by Fan S T et al. [7] randomized 195 patients with acute pancreatitis to two arms, either early ERCP done within 24 hours after admission with endoscopic papillotomy for ampullary and common bile duct stones or conservative treatment and selective ERCP with or without endoscopic papillotomy in those that

deteriorated. Early ERCP with/without endoscopic papillotomy was associated with reduction in biliary sepsis in both patients with mild or severe acute pancreatitis with no major differences in incidence of local or systemic complications between the two groups. The mortality rate was however lower in the early ERCP with or without endoscopic papillotomy group [7]. Another study by Folsch et al. [8] demonstrated no reduction in complications or mortality with early ERCP within 72 hours among patients with acute biliary pancreatitis with no obstruction. This study suggests that early ERCP is only beneficial among patients with acute pancreatitis complicated by acute cholangitis and biliary tree obstruction, and not in severe acute pancreatitis complicated in the absence of the above complications.

Based on meta-analysis, early ERCP with sphincterotomy (within 24–72 hours) had an overall significant reduction in complication rate among patients with biliary pancreatitis (41.8% versus 31.3%, P = 0.03, k = 3) significantly among those with severe disease (57.1% versus 18.2%, P = 0.0001, k = 2) with no overall significant effect on the mortality rate (7.2% versus 6.4%, P = 0.46, k = 3) [9]. Similar findings were noted in a meta-analysis by Moretti et al. when comparing early ERCP vs. conservative management in acute biliary pancreatitis. Early ERCP was associated with reduction in complications and mortality rates by 31% and 6% respectively with significant reduction in complication rates among patients with severe pancreatitis compared to mild pancreatitis (pooled rate difference of 38.5% vs. 1.8%) [10].

ERCP should not be routinely performed in patients with acute biliary pancreatitis due to its invasiveness and risk for complications. Early ERCP has been demonstrated to reduce complication rates among patients with severe acute biliary pancreatitis in the absence of cholangitis or biliary obstruction unlike among patients with mild disease. Early ERCP +ES may be considered among patients with acute biliary pancreatitis with severe biliary pancreatitis rather than among patients with mild acute biliary pancreatitis unless when having standard indications for ERCP + ES such as cholangitis, biliary obstruction [11]. However, proponents of early conservative management argue that early routine ERCP may lead to unnecessary ERCPs with related complications as the offending gallstone has passed in majority of the cases at the time of diagnosis [12, 13] and also with looming uncertainty of whether early ERCP improved prognosis of acute gallstone pancreatitis. Early ERCP is also technically difficult in acute pancreatitis due to ampulla and duodenal edema. It is therefore recommended by the ESGE that ERCP with or without endoscopic sphincterotomy among patients with acute biliary pancreatitis without cholangitis be reserved for patients with persistent biliary obstruction after a period of conservative management regardless of the severity [14, 15]. Cholecystectomy can be performed later after ERCP + ES (usually 4 to 6 weeks) to prevent recurrence of the acute pancreatitis [9]. Among patients with mild acute biliary pancreatitis, early laparoscopic cholecystectomy with intraoperative cholangiography is recommended. If intraoperative cholangiography reveals common bile duct stones with failed laparoscopic clearance of the stones, then post-operative ERCP should be performed [9].

Less invasive imaging modalities such as EUS and MRCP should be used to screen for choledocholithiasis in suspicious cases in the absence of cholangitis and/or jaundice.
