A meta-analysis of 43 studies that looked at single balloon, double balloon,spiral enteroscopy and short scope double balloon found 83% biliary cannulation success rates for spiral and single balloon methods and 95% success rates for long scope and short scope double balloon, with adverse events ranging from 0%-3%. Gastroscopes are now less commonly used, predominantly only in older patients, without entero-enteric anastomosis. However, they are still used for initial inspection and for primary visualization of anastomose-type. Patient anatomy with long afferent loops or post Roux-en-Y anastomosis who require subsequent ERCP, may require an enteroscope longer than 170 cm for forward-viewing endoscopic techniques . Besides papilla size, location, duodenal positioning, PAD, and iatrogenic patient varied anatomy, other factors that lead to swelling of the papilla also contribute to difficult cannulation. In the case of biliary malignancies, tumor infiltration of the papilla or duodenum can make the papilla difficult to find. In addition, malignancy makes the cystic tracts and vasculature more friable; this leads to more papillary edema, trauma and bleeding, with fewer cannulation attempts. Last, even in patients with normal anatomy and easily visualized papilla, multiple attempts of SBC can traumatize the papilla and extensively opacify the pancreas, these factors in themselves can distort visualization of the papilla and can make further attempts even more difficult.When SBC using the techniques described is not easily achieved, drainage planter pot it is considered a difficult cannulation. Over the years, there have been several attempts to objectively define difficult cannulation. Most definitions use a combination of a minimum number of cannulation attempts, typically 5 to 15, and a minimum time spent on standard cannulation techniques, typically greater than 5 to 20 min.

The number of inadvertent MPD injections or cannulations may also be considered part of the definition of difficult cannulation, with some studies suggesting > 4 MPD cannulations as the limit. Recently, the European Society of Gastrointestinal Endoscopy guidelines defined difficult biliary cannulation in an intact papilla as any procedure in which the duration of cannulation attempt exceeded 5 min or 5 attempts, or a procedure with more than one unintentional MPD cannulation or opacification . However, there is no uniform definition of what comprises a cannulation attempt. Friedland et al defined a cannulation attempt as any repositioning or wedging of the cannulation device while attempt SBC, while Bailey et al defined an attempt as sustained contact between the cannulation device and the papilla for five seconds or more. A 2013 study that compared the accuracy of cannulation time versus cannulation attempts asdetermined by two third party observers in 14 patients found that there was significant disagreement between observers in terms of observed number of attempts, illustrating the difficulty and variation in defining a cannulation attempt and thus difficult biliary cannulation when using number of attempts. Regardless of which definition is used, it is generally accepted that once difficult cannulation is encountered, the risk of PEP or complete failure of the procedure is dramatically increased. It is important to note that when the purpose of SBC is for pancreatic intervention only, cannulation of the minor papilla can be pursued as an alternative to the methods discussed below. Although SBC of the major papilla the most common and effective method used for management of pancreatic diseases, when access to the major papilla is difficult or impossible due to severe duct distortion or obstructive mass, cannulation of the minor papilla may be easier and safer than persistent attempts at major duct cannulation.

The minor papilla is the papilla of the accessory pancreatic duct, or sometimes, a variant duct anatomy in pancreas divisum . Access to the minor papilla enables therapeutic options for pancreatic diseases such as chronic or recurrent acute pancreatitis and pseudocysts, but not for biliary disease as the minor papilla does not connect to the CBD. Studies have shown minor papilla SBC success rates using WGC range from 74%-90% and a PEP rate of 10%-14%. SBC in the pediatric population appears to have similar success and complicationrates to the adult population when performed by an experienced advanced endoscopistbased on a number of large series. Difficult cannulation in the pediatric population is most frequently due to not having properly sized sphincterotomes designed for smaller papillae, and, in rare cases, biliary atresia . The pancreatic guide wire technique involves the placement of a guide wire into the MPD and then attempting to cannulate the biliary duct. A guide wire in the MPD helps straighten the intramural segment of the bile duct and direct the ST or other catheter into the bile duct and thus reduces the chance of accidental cannulation of the MPD. When the pancreatic guide wire method is combined with WGC, it is known as the double guide wire technique . A retrospective study involving 363 and a prospective multi-center RCT in 274 patients comparing PGT to early DGT found no difference in the success rate of cannulation or in PEP rates. However, a recent meta-analysis of 7 RCTs including 577 patients found that using DGT increased the risk of PEP when compared other techniques including standard WGC, MPD, and early pre-cut. Another technique is to place a temporary pancreatic stent and then perform WGC above the stent, called wire-guided cannulation over a pancreatic stent technique. A short 5-Fr pancreatic stent between 2 cm to 5 cm can be used, with the proximal tip not past genu to prevent duct injury. After placement of the pancreatic stent, the papilla is then cannulated using the WGC technique above the stent. The pancreatic stent all but ensures that no further accidental cannulation of the MPD can occur.

An abdominal x-ray should be performed 2 wk after the procedure to confirm spontaneous passage; if the stent has not passed, a stent removal procedure may be needed. The advantages of the WGC-PS technique is that a pancreatic stent is easy to insert, especially if a pancreatic guide wire is already in place, and has been shown to lead to a significant lower rate of PEP, with various studies showing rates reduced from as high as 23% to less than 3% after placement of a PD stent. A recent retrospective study of 177 patients compared WGC-PS to DGT found that both groups had similar cannulation rates, but the WGC-PS had lower rates of PEP . In this study however, about half of the cases that failed DGT were successfully salvaged with WGC-PS. The WGC-PS technique is also more cost effective, most likely due to the lower rates of PEP, and can be combined with other ancillary methods of cannulation such as needle-knife sphincterotomy. Due to lower rates of PEP seen with pancreatic duct stenting, the ESGE suggests a placement of a pancreatic duct stent both prior to both wire-based cannulation methods as well as and precut techniques. It is important to note, however, that pancreatic duct stenting has not been shown to reduce PEP in the pediatric population. In fact, a 2015study of 432 ERCPs in the pediatric population found that placing a prophylactic pancreatic stent was actually associated with a significantly higher rate of PEP . The cause is unclear, but the authors suggest that it may be related to physiologic differences and the smaller size of the pancreatic ducts in the pediatric population.When biliary cannulation using the techniques mentioned above fails, many endoscopists opt to create a papillotomy to access the hepatopancreatic ampulla; this may involve the sphincter of Oddi, thereby performing a sphincterotomy, or be performed staying above the sphincter, i.e., a firstulotomy. These techniques are collectively known as precut techniques to facilitate access to the biliary tree and require an intimate understanding of papillary anatomy to ensure a safe and effective procedure. The most common tool employed in precut techniques is the needle-knife, plant pot with drainage a small precision cutting tool that cuts when current is applied. The tip should not be extended beyond the catheter further than 2 to 3 mm as the tip of the needle knife cuts easily and rapidly; over-extension of the needle knife increases the risk of perforating the back wall or causing a retroduodenal perforation. Newer “hybrid-tomes” integrate the needle-knife directly into the ST and may be easier to handle than regular needle knives. If possible, a pancreatic duct stent should be placed beforehand to protect the pancreatic orifice, straighten the intramural segment of the bile duct, and position the biliary duct for easier access with the ST after the cut is complete. There is currently no standard for the naming of the various precut techniques. For this review, the naming system described by Davee et al will be used . Precut papillotomy: In precut papillotomy , the needle knife is used to dissect the major duodenal papilla to visualize and cannulate the CBD. Typically, needle-knife is placed at the 11-12 o’clock position of the papillary orifice and cut upward along the midline of the intraduodenal segment of the bile duct to expose the CBD. The biliary sphincter muscle can be recognized by its whitish onion-skin appearance. Once this muscle is exposed, the papilla can often be seen as a red dot or nipple-like structure. If examined carefully, bile may be seen flowing from the papilla.

The papilla can then be cannulated or the biliary sphincter can be transected further and then cannulation afterwards can be performed. Precut fistulotomy: In a precut fistulotomy, an incision is made using a needle knife in an area of the papilla, above the papillary orifice, that covers the intraduodenal segment of the distal CBD to create a fistula between the duodenal lumen and the CBD lumen. The incision can be extended downward towards the papillary orifice or upward, depending on the initial incision site. The precut fistulotomy technique leaves the sphincter and papillary orifice intact and creates a fistula that allows the endoscopist to directly cannulate the CBD. At least in theory and based on anecdotal evidence, this method reduces the risk of thermal injury to the pancreatic orifice and therefore the risk of PEP. A variation of this technique, the supra-papillary puncture, creates direct duodenocholedochal access using a catheter fitting with a needle to directly puncture the biliary duct under fluoroscopic guidance without cautery. When combined with EUS, this method has been shown to reduce the rate of PEP while having seemingly acceptable perforation rates. Transpancreatic precut sphincterotomy: Achieving an adequate precut papillotomy or fistulomy using a needle knife may be difficult in patients with small or difficult tolocate papilla. For such patients, the transpancreatic precut sphincterotomy may be a viable alternative method. First reported in 1995 by Goff, the TPS method uses a standard ST oriented toward the CBD at approximately 11 o’clock that is inserted superficially in the ampulla or MPD. The ST itself is then used to incise upward to perform a papillotomy. The advantages of TPS include not needing to exchange the ST for a needle-knife device and better control of the depth of incision compared to needle knife device. Although TPS alone carries a risk PEP of 9%, likely due to irritation and edema involving the MPD, placement of a PD stent after TPS has been shown to reduce the incidence of PEP to 4%.Early studies of precut techniques showed PEP rates to be as high as 15% to 20%, an alarmingly high number that is 2-3 times the PEP rate for uncomplicated SBC. However, it was unclear whether these rates were attributable to using needle knife precut techniques or due to the multiple attempts at SBC already performed. Many endoscopists now advocate for early precut techniques when difficult cannulation is predicted or recognized early on to reduce the risk of PEP. Several studies have compared the cannulation success and PEP rates of early precut techniques to persistent standard cannulation attempts. These studies were analyzed in five metaanalysis. Four of the five meta-analysis concluded there was not significant difference in SBC success rates between the two groups, with only Sundaralingam et al finding increased SBC success in the early precut group . Four of the studies noted lower PEP rates in the precut group, though the different was not significant in Navaneethan et al and Choudhary et al , and none were adequately powered to assess the difference. Two studies have compared PEP rates between early precut techniques and using pancreatic duct stents after successful SBC in difficult cannulation using persistence. A 2016 RCT of 50 early precut patients and 50 patients who underwent MPD stenting after difficult cannulation without precut techniques found similar rates of PEP of approximately 4% .