Deep Cannulation Research Articles

ERCP without radiation during pregnancy in the minimal invasive world

The current guidelines recommend endoscopic retrograde cholangiopancreatography (ERCP) procedures in pregnant women with minimal radiation exposure. Regarding the safety of ERCP during pregnancy, data are limited in the literature. In this study, we report our experience with five ERCP procedures performed in five pregnant women without radiation at a single tertiary health center. Between May 2007 and February 2012, five pregnant patients underwent ERCP without radiation, analyzed retrospectively. Clinical disease was confirmed with either pre-procedure ultrasonography and magnetic resonance cholangiopancreatography in all patients. In all cases, selective deep cannulation was performed and confirmed by the aspiration and/or direct visualization of the bile. The data regarding laboratory, ultrasonography, magnetic resonance imaging, endoscopic findings, and clinical course of the patients were analyzed. Fetal complications were noted at delivery and 30 days postdelivery follow-up. The mean patient age was 26 years (22-33) and the mean duration of pregnancy was 20 weeks (12-32). In all cases, no secondary ERCP procedures were needed. Also, no maternal and fetal adverse events and complications were determined after the procedures or on follow-up. All stages of the procedure including cannulation, sphincterotomy, and stone extraction were performed without the use of fluoroscopy. As far we know, there is no report in the literature regarding the failure of endoscopic retraction of stones without fluoroscopy during pregnancy. Our series notes that ERCP is safe and prevents recurrent biliary pancreatitis during pregnancy. Unfortunately, due to the small limited number of patient data, our study notes the requirement of further large randomized and controlled series.

Su1344 Early Precut Fistulotomy - an Effective Time Saving Strategy for a Successful Biliary Cannulation

Deep cannulation into the common bile duct is the most important step for successful biliary therapeutic endoscopy. Precut may improve the cannulation success rate usually referred to be around 80-90% after a single ERCP. However, several prospective studies have concluded that this procedure is an independent risk factor for post-ERCP complications. Moreover, the timing of the precut in the cannulation strategy is a matter of debate. We aimed at assessing success, safety, and procedure duration of an early precut fistulotomy vs a ‘classic strategy' of precut after a difficult biliary cannulation.

Mo1465 Is Double-Guidewire Technique Really Useful for Difficult Biliary Cannulation?

Mo1465 Is Double-Guidewire Technique Really Useful for Difficult Biliary Cannulation? Su Jin Kim*, Dae Hwan Kang, Hyung Wook Kim, Cheol Woong Choi, Young MI Hong, Joung Boom Hong, Byoung Hoon Ji, MIN Dae Kim, Jae Hyung Lee Internal Medicine, Pusan National University Yangsan Hospital, YangSan -Si, Gyeongnam, Republic of Korea; Internal Medicine, Bongseng Memorial Hospital, Pusan, Republic of Korea Background and Aim: Double-guidewire technique (DGT) has been reported to be useful for difficult biliary cannulation. Needle-knife fistulotomy (NKF) is also used in failed standard biliary cannulation. The aim of this study was to compare the success rate and complications between the DGT and NKF in patients with difficult biliary cannulations. Methods: Patient who underwent endoscopic retrograde cholangiopancreatography (ERCP) between January 2009 and September 2012 were eligible for this study. DGT or NKF were perfomed if deep biliary cannulation was not achieved despite of five mininutes of attempted cannulationthan or more than three attempted unintentional pancreatic cannulations. Patients with unsuccessful DGT underwent NKF as alternative procedure. The success rate of cannulation and the frequency of post-ERCP pancreatitis (PEP) were investigated. Result A total 1550 ERCP cases were analyzed, the total success rate of selective biliary cannulation was 94.2% (1460/1550). Of the 302 patients with unsuccessful standard cannulation technique, DGT was perfomed in 70 patients and NKF was perfomed in 199. The success rates in the DGT and NKF groups were 41.4% (29/70) versus 81.4% (162/ 199) (p 0.01). Thirty patients with unsuccessful DGT underwent NKF as alternative procedure, biliary cannulation was achieved in 70.0% (21/30). 3-step protocol (traditional cannula with guidewire, DGT, and NKF is performed sequentially) was no significant benefit in success rates compared with NKF only group (84.7% 50/59, p 0.453). The incidence rate of PEP was significantly higher in DGT group (20.0%, 14/70) than in NKF group (8.0%, 16/199) (p 0.01). There was no significant difference in bleeding incidence. Conclusion: DGT in patients with a difficult biliary cannulation resulted in a low success rate of biliary cannulation and a high incidence of PEP comparing with NKF. DGT before NKF had no statically additional benefit in cannulation success. We suggest that NKF should be considered as a first approach in difficult cannulation situations. Clinical Outcomes for cannulation

Optimal Positioning for ERCP: Efficacy and Safety of ERCP in Prone versus Left Lateral Decubitus Position

Background. ERCP is customarily performed with the patient in prone position. For patients intolerant of prone positioning, ERCP in left lateral decubitus (LLD) position offers a potential alternative. Aims. To compare efficacy and safety of ERCP in the LLD position versus prone position. Methods. Consecutive ERCP reports from August 2009 to October 2010 at Mayo Clinic Arizona were reviewed. Inclusion criteria. Age > 18 years, native papilla, and biliary indication. Primary outcome measure. Bile duct cannulation rate. Secondary outcomes. Times to ampullary localization and bile duct cannulation and complication rate. Results. ERCPs reviewed from 59 patients in two positions: 39 prone and 20 LLD. Cannulation Rate. 100% prone versus 90% in LLD (P=0.11). Median (IRQ) times. (1) Ampullary localization: 90 sec (70–110) prone versus 100 sec (80–118) (P=0.16); (2) bile duct cannulation: 140 sec (45–350) prone versus 165 sec (55–418) LLD (P=0.54). Complications. No periprocedure; postprocedure 4 (10%) prone versus 3 (15%) LLD (P=0.65). Conclusion. ERCP performed in LLD position allowed deep bile duct cannulation in 90% of patients without significantly increased procedural times or rate of complications as compared to prone position.

Precut sphincterotomy: A reliable salvage for difficult biliary cannulation

Even experienced endoscopists have 90% success in achieving deep biliary cannulation with standard methods. Biliary cannulation may become difficult in 10%-15% of patients with biliary obstruction and precut (access) sphincterotomy is frequently chosen as a rescue treatment in these cases. Generally, precut sphincterotomy ensures a rate of 90%-100% successful deep biliary cannulation. The precut technique has been performed as either a fistulotomy with a needle knife sphincterotome or as a transpapillary septotomy with a standard sphincterotome. Both methods have similar efficacy and complication rates when administered to the proper patient. Although precut sphincterotomy ensures over 90% success of biliary cannulation, it has been characterized as an independent risk factor for pancreatitis. The complications of the precut technique are not limited to pancreatitis. Two more important ones, bleeding and perforation, are also reported in some publications as being observed more commonly than during standard sphincterotomy. It is also reported that precut sphincterotomy increases morbidity when performed in patients without dilatation of their biliary tract. Nevertheless, precut sphincterotomy is a good alternative as a rescue method in the setting of a failed standard cannulation method. This paper discusses the technical details, timing, efficacy and potential complications of precut sphincterotomy.

Angled- or straight-tipped hydrophilic guidewire in biliary cannulation: a prospective, randomized, controlled trial

Deep biliary cannulation is the key for successful endoscopic retrograde cholangiopancreatography (ERCP) procedures. Guidewire-assisted cannulation is associated both with a higher success rate and a reduced risk of post-ERCP pancreatitis compared with standard catheter cannulation. However, to our knowledge there are no prospective, randomized studies comparing the use of different guidewires in biliary cannulation. The goal of this study was to compare the performance of an angled-tipped guidewire (AGW) with a straight-tipped guidewire (SGW) in achieving successful deep biliary cannulation. Patients with intended biliary cannulation of an intact papilla were prospectively randomized to angled- or straight-tipped hydrophilic guidewire arms in a tertiary, referral, university hospital setting. Randomized cannulation method was applied either until successful cannulation of the bile duct or until 2 min had passed. Crossover was not included in the study protocol. The main outcome measurements were the cannulation success rate and duration of cannulation. Of the 239 consecutive patients, 155 patients were randomized: in the final analysis 70 patients were included in the AGW arm and 83 patients in the SGW arm. Cannulation time [median; seconds (s)] was shorter with the AGW compared with the SGW (20 vs. 63 s, p = 0.01). There was no difference in the cannulation success rate or the complication rate between the two study groups. AGW may facilitate biliary cannulation in ERCP.

New modification of deep biliary cannulation using endoscopic–radiologic rendezvous technique for palliative treatment of malignant obstructive jaundice

AimTo describe a new simple modification of deep biliary cannulation using combined endoscopic–radiologic technique and evaluate its technical and clinical success for palliative treatment of malignant obstructive jaundice. Patients and interventionWe used this technique in 25 patients with inoperable malignant biliary obstruction and failed endoscopy procedures alone. Using angiographic methods, an introducer of long arterial sheath, over a guide wire was passed to overcome the site of obstruction. Our amendments lie in using a stiff introducer to allow support of the guide wire during its navigation through the obstruction site, followed by passage of the introducer together with the guide wire to the duodenum, while the introducer in place; the hydrophilic guide wire with its slippery end should be replaced with a long ordinary guide wire which is used in ERCP because it could be easily grasped with the dormia basket. ResultsTechnical success rates were 100%, internal biliary stents were successfully placed in a one-step procedure at the appropriate position in all patients with adequate duct drainage. Clinical success rates were 92% within 48–72h and 8% within 7days. Minor complications occurred in 4/25 (16%) patients, with no reported major complication. The median procedure time was 40min. ConclusionThis simple modification was technically and clinically successful for palliative treatment of inoperable malignant biliary obstruction with failed endoscopy procedures alone.

Difficult Biliary Access for ERCP

Endoscopic retrograde cholangiopancreatography (ERCP) is a technically-demanding procedure. The ability to selectively cannulate the bile duct and pancreatic duct (PD) quickly and atraumatically is the key to successful therapeutic ERCP, and to minimizing post-ERCP complications, especially pancreatitis (PEP). Prophylactic stenting of the PD has significantly reduced the risk of severe PEP. Difficult ERCP access refers to the length of time and number of attempts it takes to achieve deep cannulation of the desired duct. If biliary access cannot be achieved quickly, PD stenting over a guide wire is recommended, which facilitates further attempts to enter the bile duct. Familiarity with guide wires and needle knife papillotomy technique are necessary to achieve close to 100% biliary cannulation. Anatomic abnormalities, from gastric outlet strictures, periampullary diverticula, and ampullary masses to surgical rearrangement of the upper GI tract, contribute to the difficulty of performing ERCP. Adjunctive techniques to overcome these problems include percutaneous transhepatic biliary access and endoscopic ultrasound (EUS)-guided puncture of the bile duct through the stomach or duodenal wall. Therapeutic EUS is emerging as a major tool in the management of pancreatic and biliary disease, and will likely replace many therapeutic ERCP techniques in the next decade.

New role of the dual knife for precut papillotomy in difficult bile duct cannulation

The dual knife is usually used for endoscopic submucosal dissection (ESD). To date, however, there have been no clinical trials of the safety and effectiveness of precut papillotomy using the dual knife for biliary access in patients failing conventional endoscopic retrograde cholangiopancreatography (ERCP) cannulation. We herein report 18 patients who underwent precut papillotomy with the dual knife. All had intact papilla, and had failed deep cannulation of the bile ducts. After successful biliary cannulation and standard endoscopic sphincterotomy, if necessary, stone removal or plastic or metal stent insertion was attempted. Selective bile-duct cannulation was achieved in all 18 patients (100%), at an average time of 4.2 min (range, 3-6 min). Of these 18 patients, six had malignant bile duct obstruction and 12 had common bile duct stones. One patient developed post-ERCP pancreatitis, which resolved after conservative management. There were no deaths related to the procedure.

The ERCP quality network benchmarking project: a preliminary comparison of practice in UK and USA

ObjectiveThe Endoscopic retrograde cholangiopancreatography (ERCP) Quality Network is a voluntary system for submission of data to generate individual report cards and benchmarking. The aim of this study was to compare...

Sa1127 Colonoscopy Attendance and Quality After Implementation of an Internet Based Educational Program

Introduction: Selective deep biliary cannulation fails in 15-30% of cases even in experienced hands. Repeated and prolonged attempts at cannulation increases risk of post ERCP pancreatitis. Supra papillary needle knife fistulotomy (NKF) is a very useful, yet controversial rescue technique in cases of difficult biliary cannulation. This allows access when cannulation via the orifice cannot be achieved. Concerns have been expressed about its safety. Aims/ Background: The aim of this retrospective study was to evaluate efficacy and safety of NKF by a gastroenterologist, with experience in this technique. Method: This was a single centre study of data from a single operator who uses NKF. A needle knife is used to enter the intramural duct clear of the orifice. The cut is then extended if necessary with a standard sphincterotome. The study was retrospective, looking at data from January 2000 to May 2011, by searching the data available on the endoscopy software ‘ENDOSCRIBE', medical notes and radiology reports. Results: All the patients fulfilled either clinical or radiologic criteria for ERCP. A total of 2639 ERCP were done in this period, with 82.75% (2184/ 2639) performed by the endoscopist who uses NKF. 200 (7.5% of all and 9.1% of the operator's procedures) involved NKF. The age group of the patients ranged from 20 to 96 (mean age 67.5years). The majority 52.5% (105/200) were above 70 years, with only 5% (9/200) being less than 30 years. 63.5% (127/200) were women, 64% (128/200) jaundiced and 70% (140/200) had a dilated common bile duct. Overall biliary cannulation rate in this extremely difficult cohort of patients was 58% (116/200) and 80.17% (93/116) had definitive treatment. NKF was successful, in 82.9% (39/47) of patients with choledocholithiasis who had dilated ducts and in 81.25% (26/32) of strictures with dilated ducts. 0.5% (1/200) had bleeding, mild pancreatitis (3xelevation of amylase) in 3.5% (7/200), necrotising pancreatitis (CT proven) in 1% (2/200) and perforation in 1% (2/200). The overall complication rate, considering each of the above as a separate event, was 15% (15/100) for the first 100 procedures and 6% (6/100) for the latter half of the study group. Conclusion: This is one of the largest data from UK looking at needle knife fistulotomies in ERCP, in difficult to access common bile ducts, often being referred after several previously failed attempts. NKF is a safe and effective procedure in a selected group of patients, as long as it is done by an experienced endoscopist. The learning curve for the procedure is steep and complication rate goes down as the technique improves with experience, which has a pivotal role in the success of the procedure. Gender Distribution

Sa1126 Ten Year Data on Needle Knife Fistulotomy in a University Teaching Hospital

Introduction: Selective deep biliary cannulation fails in 15-30% of cases even in experienced hands. Repeated and prolonged attempts at cannulation increases risk of post ERCP pancreatitis. Supra papillary needle knife fistulotomy (NKF) is a very useful, yet controversial rescue technique in cases of difficult biliary cannulation. This allows access when cannulation via the orifice cannot be achieved. Concerns have been expressed about its safety. Aims/ Background: The aim of this retrospective study was to evaluate efficacy and safety of NKF by a gastroenterologist, with experience in this technique. Method: This was a single centre study of data from a single operator who uses NKF. A needle knife is used to enter the intramural duct clear of the orifice. The cut is then extended if necessary with a standard sphincterotome. The study was retrospective, looking at data from January 2000 to May 2011, by searching the data available on the endoscopy software ‘ENDOSCRIBE', medical notes and radiology reports. Results: All the patients fulfilled either clinical or radiologic criteria for ERCP. A total of 2639 ERCP were done in this period, with 82.75% (2184/ 2639) performed by the endoscopist who uses NKF. 200 (7.5% of all and 9.1% of the operator's procedures) involved NKF. The age group of the patients ranged from 20 to 96 (mean age 67.5years). The majority 52.5% (105/200) were above 70 years, with only 5% (9/200) being less than 30 years. 63.5% (127/200) were women, 64% (128/200) jaundiced and 70% (140/200) had a dilated common bile duct. Overall biliary cannulation rate in this extremely difficult cohort of patients was 58% (116/200) and 80.17% (93/116) had definitive treatment. NKF was successful, in 82.9% (39/47) of patients with choledocholithiasis who had dilated ducts and in 81.25% (26/32) of strictures with dilated ducts. 0.5% (1/200) had bleeding, mild pancreatitis (3xelevation of amylase) in 3.5% (7/200), necrotising pancreatitis (CT proven) in 1% (2/200) and perforation in 1% (2/200). The overall complication rate, considering each of the above as a separate event, was 15% (15/100) for the first 100 procedures and 6% (6/100) for the latter half of the study group. Conclusion: This is one of the largest data from UK looking at needle knife fistulotomies in ERCP, in difficult to access common bile ducts, often being referred after several previously failed attempts. NKF is a safe and effective procedure in a selected group of patients, as long as it is done by an experienced endoscopist. The learning curve for the procedure is steep and complication rate goes down as the technique improves with experience, which has a pivotal role in the success of the procedure. Gender Distribution

Feasibility of the Novel 3-Step Protocol for Biliary Cannulation—A Prospective Analysis

Traditionally, a 2-step protocol has been used for deep biliary cannulation. The purpose of the present prospective study was to find out the feasibility and safety of the novel sequential 3-step protocol (traditional cannula with guidewire, double-guidewire, and needle-knife techniques) for deep biliary cannulation. All consecutive patients admitted for endoscopic retrograde cholangiopancreatography (ERCP) to a single, very experienced ERCP endoscopist during the year 2009 with intended biliary cannulation and with unhindered access to a native papilla (n=105) were included in the present study. The overall success rate for deep biliary cannulation was 99% (104/105). Cannulation with cannula and guidewire was attempted in all patients and proved successful in 80% (84/105) of the attempts, the double-guidewire technique was applied in 19% (20/105) and was successful in 65% (13/20) of the cases, and the needle-knife technique was applied in 7% (7/105) with success in all cases. The median cannulation time was 1 minute (range, 0 to 27 min). The rate of post-ERCP pancreatitis was 3% (3/105) and post-ERCP cholangitis 2% (2/105). We conclude that in experienced hands, the novel sequential 3-step protocol for biliary cannulation tested herein proved to be an effective cannulation protocol with the overall success rate of 99%. The complication rate of these ERCP procedures (5%) was within acceptable limits.

Mo1325 A Prospective Assessment of Pancreatic Techniques Used to Achieve Common Bile Duct Cannulation in ERCP

Use of pancreatic techniques (PTs) is a new and useful method to improve biliary cannulation. Guidewire (GW) placement into the main pancreatic duct (MPD) has been shown to be effective in increasing the rate of common bile duct (CBD) deep cannulation. Following GW-MPD insertion, a variety of methods (see figure) can be performed to gain the CBD. Our aim was to evaluate prospectively its use and effectiveness in an intermediate volume ERCP unit (about 150 procedures per year performed by a single endoscopist).

Sa1503 EUS-Based ERCP Reduces Risk Exposure in Pregnant Patients With Suspected Choledocholithiasis

Sa1503 EUS-Based ERCP Reduces Risk Exposure in Pregnant Patients With Suspected Choledocholithiasis

Results of repeat endoscopic retrograde cholangiopancreatography after initial biliary cannulation failure following needle‐knife sphincterotomy

After failed biliary cannulation with needle knife sphincterotomy (NKS), endoscopic retrograde cholangiopancreatography (ERCP) is sometimes repeatedly performed in clinically stable patients; however, there are few reports about the results. This study assessed the results of repeated ERCPs after failure with NKS. After failed NKS, patients who underwent repeated ERCP for the same purpose within 3 days were retrospectively identified. Success was defined as deep placement of a catheter into the common bile duct. Sixty-nine patients underwent a second ERCP procedure and, of those, six underwent a third ERCP. Of the 69 patients, cannulation was successful in 76.8% (53/69): 46 of 58 patients without additional NKS and 7 of 11 with additional NKS. Success increased to 79.7% (55/69) after the results of the third ERCP were included. Common causes of failed NKS were biliary deep cannulation failure (78.3%) and blocking of the endoscopic view due to bleeding (13.0%). There was a significant difference in success rates between the one day (65.7%) and the combined 2-3 day (88.2%) cases (P = 0.027). Except for the interval between ERCPs, there were no other factors associated with success rates. Complications occurred in 8, 11, and one patient after initial, second, and third ERCP and there was no difference of complication rates between each ERCPs. In cases with biliary cannulation failure with NKS, it is more worthwhile repeating ERCP 2 or 3 days after such failure than one day after, if the patient's condition permits delay of procedure.

Tips for Successful Endoscopic Retrograde Cholangiopancreatography in Patients with Billroth II Gastrectomy

Tips for Successful Endoscopic Retrograde Cholangiopancreatography in Patients with Billroth II Gastrectomy

Initial evaluation of a novel multibending backward-oblique viewing duodenoscope in endoscopic retrograde cholangiopancreatography

A novel multibending backward-oblique viewing duodenoscope was developed to overcome the difficult technical aspect of deep cannulation into the bile duct during endoscopic retrograde cholangiopancreatography (ERCP). The aim of the present study was to evaluate the initial experience of a novel multibending backward-oblique viewing duodenoscope (M-D scope) for ERCP. This was a retrospective review of 23 patients with native papilla who received biliary ERCP with the M-D scope between April and December 2010. The procedures were performed by two well-experienced endoscopists. In all patients, biliary cannulation and therapeutic procedure were successfully completed. In two patients with Billroth I gastrectomy, ERCP were initially attempted with a conventional single-bending duodenoscope, but biliary cannulations were unsuccessful. However, with the use of the M-D scope, biliary cannulation and therapeutic procedures were successfully completed. A novel multibending backward-oblique viewing duodenoscope is safe and feasible for therapeutic and diagnostic ERCP.

Partially covered self-expanding metal stent for unresectable malignant extrahepatic biliary obstruction: results of a large prospective series

Endoscopic biliary stenting is a well-established palliative treatment in patients with unresectable malignant biliary strictures. Obstruction of uncovered self-expanding metal stent (SEMS) due to tumor ingrowth is the most frequent complication. Partially covered SEMS might increase stent patency but could favor complications related to stent covering, such as pancreatitis, cholecystitis, and migration. The aim of this study was to evaluate the efficacy and safety of partially covered SEMS in patients with an unresectable malignant biliary stricture. Patients with malignant extrahepatic biliary obstruction treated endoscopically with partially covered SEMS were included in this multicenter, prospective, nonrandomized study. One hundred ninety-nine patients were endoscopically treated with partially covered SEMS in 32 Spanish hospitals. Clinical success after deep cannulation was 96%. Early complications occurred in 4% (3 pancreatitis, 2 cholangitis, 1 hemorrhage, 1 perforation, and 1 cholecystitis). Late complications occurred in 19.5% (18 obstructions, 10 migrations, 6 cholangitis without obstruction, 3 acute cholecystitis, and 2 pancreatitis), with no tumor ingrowth in any case. Median stent patency was 138.9 ± 112.6days. One-year actuarial probability of stent patency was 70% and that of nonmigration was 86%. Multivariate analysis showed adjuvant radio- or chemotherapy as the only independent predictive factor of stent patency and previous insertion of a biliary stent was the only predictive factor of migration. The partially covered SEMS was easily inserted, had a high clinical success rate, and prevented tumor ingrowth. The incidence of possible complications related to stent coverage, namely, migration, pancreatitis, and cholecystitis, was lower than in previously published series.

Effect of the time of day on the success and adverse events of ERCP

Physician fatigue and decreased concentration have been proposed as causes of lower completion and adenoma detection rates in afternoon colonoscopies compared with morning colonoscopies. ERCP is a technically demanding and highly operator-dependent procedure, and its success may similarly be affected in the afternoon compared with the morning. To compare cannulation success and adverse events between ERCP procedures performed in the morning and afternoon. Retrospective cohort study. Tertiary referral center. Patients with no previous papillary intervention who underwent ERCP at our institution between November 2006 and November 2008. Cannulation success, procedure completion rates, length of procedures, and adverse events. A total of 296 patients were studied; 114 patients (38.5%) underwent a procedure in the morning and 182 patients (61.5%) underwent a procedure in the afternoon. There were 139 male patients (47.0%). The mean patient age was 59.1 years. The deep cannulation success rate was 95.3% overall, with similar rates when performed in the morning (98.3%) and afternoon (94.0%) (P = .08). When the start time was evaluated as a continuous hour-by-hour variable, there was also no significant difference in deep cannulation success rates (P = .30). Procedure completion rates were similar in both groups (morning, 93.9%; 94.0%, afternoon; P = .97). Adverse events (8.8% for morning procedures vs 7.1% for afternoon procedures, P = .61) and length of procedures (40 minutes for morning procedures vs 40 minutes for afternoon procedures, P = .87) were also similar between the 2 groups. Small sample size and retrospective study. The timing of ERCP, morning versus afternoon, does not seem to affect cannulation success, procedure completion rates, length of procedures, or adverse events.