Comparative study of electrical and rheological properties of different solutions used in endoscopic mucosal resection.

BACKGROUND AND AIM: The study of electrical and rheological properties of solutions to carry out endoscopic resection procedures could determinate the best candidate. An ex vivo study with porcine stomachs was conducted to analyze electrical resistivity (R) and rheological properties (temperature, viscosity, height and lasting of the cushion) of different substances used in these techniques. METHODS: Tested solutions were: 0.9% saline (S), platelet-rich plasma (PRP), Gliceol (GC), hyaluronic acid 2% (HA), Pluronic-F127 20% (PL), saline with 10% glucose (GS), Gelaspan (GP), Covergel-BiBio (TB) and PRP with TB (PRP+TB). Measurements of electrical and rheological properties were done at 0, 15, 30, 45 and 60 min after submucosal injection. RESULTS: Solutions showed a wide variability of transepithelial R after submucosal injection. Substances able to maintain the highest R 60 min postinjection were TB (7 × 104 Ω), HA (7 × 104 Ω) and PL (7 × 104 Ω). Protective solutions against deep thermal injury (Tª lower than 60°C) were PL (47.6°C), TB (55°C) and HA (56.63°C). Shortest time to carry out resections were observed with GC (17.66″), PRP (20.3″) and GS (23.45″). Solutions with less cushion decrease (<25%) after 60 min were TB (11.74%), PL (18.63%) and PRP (22.12%). CONCLUSIONS: Covergel-BiBio, PL and HA were the best solutions with long-term protective effects (transepithelial R, lower thermal injury and less cushion decrease). Solutions with quicker resection time were GC, PRP and GS.

Submucosal injection of platelet-rich plasma in endoscopic resection of large sessile lesions.

AIM: To prospectively evaluate the efficacy of submucosal injection of platelet-rich plasma (PRP) on endoscopic resection of large sessile lesions. METHODS: Eleven patients were submitted to endoscopic mucosal resection (EMR) with prior injection of PRP, obtained at the time of endoscopy. Patients were followed during 1 mo. The incidence of adverse events (delayed bleeding or perforation) and the percentage of mucosal healing (MHR) after 4 wk were registered. RESULTS: EMR was performed in 11 lesions (46.4 mm ± 4 mm, range 40-70 mm). Delayed bleeding or perforation was not observed in any patient. Mean ulcerated area at baseline was 22.7 cm2 ± 11.7 cm2 whereas at week 4 were 2.9 cm2 ± 1.5 cm2. Patients treated with PRP showed a very high MHR after 4 wk (87.5%). CONCLUSION: PRP is an easy-to-obtain solution with proven and favourable biological activities that could be used in advanced endoscopic resection.

Endoscopic shielding technique with a newly developed hydrogel to prevent thermal injury in two experimental models.

BACKGROUND AND AIM: A newly developed hydrogel, applied through the endoscope as an endoscopic shielding technique (EndoSTech), is aimed to prevent deep thermal injury and to accelerate the healing process of colonic induced ulcers after therapeutic endoscopy. METHODS: Lesions were performed in rats (n = 24) and pigs (n = 8). Rats were randomized to receive EndoSTech (eight rats each) with: saline (control), hyaluronic acid and product. In pigs, three ulcer sites were produced in each pig: endoscopic mucosal resection (EMR)-ulcer with prior saline injection (A; EMR-saline), EMR-saline plus EndoSTech with product (B; EMR-saline-P), and EMR with prior injection of product plus EndoSTech-P (C; EMR-P-P). At the end of the 14-day study, the same lesions were performed again in healthy mucosa to assess acute injury. Animals were sacrificed after 7 (rats) and 14 (pigs) days. Ulcers were macroscopically and histopathologically evaluated. Thermal injury (necrosis) was assessed with a 1-4 scale. RESULTS: In rats, treatment with product improved mucosal healing comparing with saline and hyaluronic acid (70% vs 30.3% and 47.2%; P = 0.003), avoiding mortality (0% vs 50% and 25%; P = 0.038), and perforation (0% vs 100% and 33.3%; P = 0.02); respectively. In pigs, submucosal injection of product induced a marked trend towards a less deep thermal injury (C = 2.25-0.46 vs A and B = 2.75-0.46; P = 0.127). Mucosal healing rate was higher with product (B = 90.2-3.9%, C = 91.3-5.5% vs A = 73.1-12.6%; P = 0.002). CONCLUSIONS: This new hydrogel demonstrates strong healing properties in preclinical models. In addition, submucosal injection of this product is able to avoid high thermal load of the gastrointestinal wall.

Fecal Calprotectin Levels Are Closely Correlated with the Absence of Relevant Mucosal Lesions in Postoperative Crohn's Disease.

BACKGROUND: Fecal calprotectin (FC) is the best noninvasive biomarker of disease activity in inflammatory bowel disease. Its correlation with endoscopic mucosal lesions could save inconvenient, expensive, and repeated endoscopic examinations in particular clinical settings. PATIENTS AND METHODS: To assess the correlation between FC and the existence and severity of endoscopic postoperative recurrence (POR), a group of clinically stable outpatients with Crohn's disease for whom an ileocolonoscopy was routinely planned to assess POR were invited to collect a stool sample before starting bowel cleansing to measure FC. POR was graded by means of Rutgeerts endoscopic score. RESULTS: One hundred nineteen ileocolonoscopies were included, 42% with endoscopic POR. FC was significantly lower in the absence of endoscopic POR and in the absence of any endoscopic lesion. The area under the receiver operating characteristic curve was 0.76 (95% confidence interval, 0.68-0.85) for the diagnosis of the absence of lesions and 0.75 (95% confidence interval, 0.66-0.84) for endoscopic POR. Better sensitivity and negative predictive value were observed when combining FC and serum C-reactive protein (CRP), leading to a sensitivity of 82%, a specificity of 53%, and negative and positive predictive values of 81% and 54%, respectively, for the prediction of endoscopic POR with a combination of FC 100 µg/g and CRP 5 mg/L cutoff values. CONCLUSIONS: FC correlates closely with endoscopic POR in clinically stable postoperative patients with Crohn's disease and, when used in combination with CRP, might save endoscopic examinations and allow for a high-grade suspicion of endoscopic POR in the long-term monitoring of these patients.

Efficacy of platelet-rich plasma as a shielding technique after endoscopic mucosal resection in rat and porcine models.

BACKGROUND AND STUDY AIMS: The aims were to assess the efficacy of endoscopic application of Platelet-rich plasma (PRP) to prevent delayed perforation and to induce mucosal healing after endoscopic resections. PATIENTS AND METHODS: Colonic induced lesions were performed in rats (n = 16) and pigs (n = 4). Animals were randomized to receive onto the lesions saline (control) or PRP. Animals underwent endoscopic follow-up. Thermal injury was assessed with a 1 - 4 scale: (1) mucosal necrosis; (2) submucosal necrosis; (3) muscularis propria necrosis; and (4) serosal necrosis RESULTS: Saline treatment showed 50 % of mortality in rats (P = 0.02). Mean ulcerated area after 48 hours and 7 days was significantly smaller with PRP than with saline (0.27 ±â€Š0.02 cm(2) and 0.08 ±â€Š0.01 cm(2) vs. 0.56 ±â€Š0.1 cm(2) and 0.40 ±â€Š0.06 cm(2); P < 0.001). The incidence of thermal injury was significantly lower with PRP (1.25 ±â€Š0.46) than in controls (2.25 ±â€Š0.50); P = 0.006. The porcine model showed a trend toward higher mucosal restoration in animals treated with PRP than with saline at weeks 1 and 2 (Median area in cm(2): 0.55 and 0.40 vs. 1.32 and 0.79) CONCLUSIONS: Application of PRP to colonic mucosal lesions showed strong healing properties in rat and porcine models.

Single oral dose of maraviroc does not prevent ex-vivo HIV infection of rectal mucosa in HIV-1 negative human volunteers.

OBJECTIVE: Maraviroc (MVC) is a potential candidate for 'on demand' preexposure prophylaxis. In the present study, we evaluated the efficacy of a single oral dose of MVC to prevent ex-vivo HIV-1 infection of rectal tissue in humans. DESIGN AND METHODS: Eight HIV-1-negative healthy volunteers received a single oral dose of MVC (300 or 600 mg), and two additional volunteers received tenofovir disoproxil fumarate/emtricitabine (TDF/FTC, 300/200 mg) for 10 days. Rectal biopsies were performed prior to the ex-vivo challenge (day 0), at day 7 (4 h after MVC) or after 10 days with TDF/FTC. Rectal biopsies were infected ex-vivo, and viral inhibition and CCR5 occupancy was analyzed. MVC concentration in plasma and rectal tissue was measured just after biopsy and after viral incubation. RESULTS: Ex-vivo rectal tissue protection with MVC was incomplete in all but two participants, whereas TDF/FTC avoided ex-vivo infection in the two controls. Median dose-normalized concentration of MVC was significantly higher in rectal tissue than in plasma (561.1 and 155.1 ng/ml, respectively). A significant loss of MVC during the virus incubation (about 60%) and a low CCR5 occupancy (approximately 45%) were detected in rectal cells. CONCLUSIONS: An ex-vivo challenge with a single oral dose of MVC does not prevent ex-vivo infection of human rectal mucosa. The lack of prophylactic efficacy observed suggests that 'on demand' MVC preexposure prophylaxis would not prevent rectal HIV-1 transmission.

Improving the quality of colonoscopy bowel preparation using a smart phone application: a randomized trial.

BACKGROUND AND AIM: Getting ready for a colonoscopy is difficult and involves many steps. Information given to patients is very important for adherence to treatment. We created a novel smart phone application (SPA) aimed to increase bowel preparation quality and patient satisfaction. METHODS: We carried out a prospective, endoscopist-blinded, randomized, controlled trial. We enrolled 260 outpatient (58% female, age range 21-75 years) owners of a smartphone. Patients were allocated to two different protocols: instructions provided by SPA (SPA group; n = 108) or written instructions with visual aids (control group; n = 152). All procedures were carried out in the afternoon and patients received the same purgative regimen (2 L polyethylene glycol (PEG) solution plus ascorbic acid), in a full-dose same-day regimen. The study was designed to detect an improvement in quality of bowel preparation using the Harefield Cleansing Scale (HCS) scale. Effect of protocol on patient satisfaction was assessed with a specific questionnaire at the time of colonoscopy. RESULTS: Proportion of patients who obtained successful bowel preparation for colonoscopy (HCS A or B) was significantly higher in the SPA group than in the control group (100% vs 96.1%, respectively; P = 0.037). Mean global HCS scores were similar in both groups. Patient-reported tolerability and overall experience with the prescribed bowel preparation were significantly higher for the SPA group than for the control group. CONCLUSION: Successful cleansing and patient acceptability with the use of SPA were superior to written instructions in outpatients submitted for colonoscopy using 2 L PEG solution plus ascorbic acid.

Addition of mesalazine for subclinical post-surgical endoscopic recurrence of Crohn's disease despite preventive thiopurine therapy: A case-control study.

BACKGROUND AND AIM: Thiopurines prevent Crohn's disease (CD) endoscopic recurrence (ER) at least in 50% of patients 1 year after surgery. This study aimed to evaluate the value of adding mesalazine in patients with subclinical ER despite preventive thiopurine therapy. METHODS: Crohn's disease patients with ileocecal resection treated with thiopurines for postsurgical recurrence prevention in whom mesalazine was added (cases) to treat ER without clinical recurrence (CR) were identified and compared with those in whom no treatment was added to thiopurines (controls). All patients were followed up for at least 1 year from the index endoscopy. Development of CR as well as evolution of mucosal lesions was evaluated. RESULTS: Thirty-seven patients were included (19 cases and 18 controls). Initial Rutgeerts' score was i2 in 16 patients (9 cases and 7 controls), and i3 in 21 patients (10 cases and 11 controls). After a median clinical follow-up of 59 months (interquartile range 22-100) from the index endoscopy, six cases (32%) and two controls (11%) developed CR (P = 0.2). After a median time to last endoscopic follow-up of 23 months (interquartile range 17-71), 18 patients (49%) showed improvement in Rutgeerts' score, 11 patients (30%) demonstrated progression of mucosal lesions, and 8 (22%) had no changes, with no differences between study groups. CONCLUSIONS: The addition of mesalazine seems to be of no benefit in patients with subclinical endoscopic recurrence while on thiopurine prevention. Moderate endoscopic postsurgical recurrence while on thiopurines may even revert with no additional therapy in some patients.

Biodegradable stents in gastrointestinal endoscopy.

Biodegradable stents (BDSs) are an attractive option to avoid ongoing dilation or surgery in patients with benign stenoses of the small and large intestines. The experience with the currently the only BDS for endoscopic placement, made of Poly-dioxanone, have shown promising results. However some aspects should be improved as are the fact that BDSs lose their radial force over time due to the degradable material, and that can cause stent-induced mucosal or parenchymal injury. This complication rate and modest clinical efficacy has to be carefully considered in individual patients prior to placement of BDSs. Otherwise, the price of these stents therefore it is nowadays an important limitation.

Microperforation of the colon: animal model in rats to reproduce mucosal thermal damage.

BACKGROUND: The aim of the present study was to develop a rat model of colonic microperforation secondary to thermal injury for future studies to assess new treatments. METHODS: Twenty-four male Sprague-Dawley rats were used in this study. Hot biopsy forceps were used for all treatments. All lesions were created in proximal left colon using the soft coagulation setting. The power setting tested was 40 W, and the durations of monopolar soft coagulation application evaluated were 2, 3, and 4 s. RESULTS: In the acute phase, 48 h after thermal injury, durations of cautery of 2 and 3 s resulted in transmural necrosis, whereas with 4 s microperforation was obtained. In the late phase, 7 d after the damage, only duration of cautery of 4 s showed deep cautery effects, with signs of peritonitis. CONCLUSIONS: We determined optimal power settings and duration of therapy in a rat model for producing electrocautery that involves transmural necrosis with microperforation.

Intensification of a raltegravir-based regimen with maraviroc in early HIV-1 infection.

BACKGROUND: Latent HIV-1-infected cells generated early in the infection are responsible for viral persistence, and we hypothesized that addition of maraviroc to triple therapy in patients recently infected with HIV-1 could accelerate decay of the viral reservoir. METHODS: Patients recently infected (<24 weeks) by chemokine receptor 5 (CCR5)-using HIV-1 were randomized to a raltegravir + tenofovir/emtricitabine regimen (control arm, n = 15) or the same regimen intensified with maraviroc (+MVC arm, n = 15). Plasma viral load, cell-associated HIV-1 DNA (total, integrated, and episomal), and activation/inflammation markers were measured longitudinally. RESULTS: Plasma viral load decayed in both groups, reaching similar residual levels at week 48. Total cell-associated HIV-1 DNA also decreased in both groups during the first month, although subsequently at a slightly faster rate in the +MVC arm. The transient increase in two long terminal repeat (2-LTR) circles observed in both groups early after initiation of treatment decreased earlier in MVC-treated individuals. Early (week 12) increase of CD4 T-cell counts was higher in the +MVC arm. Conversely, CD8 T-cell counts and CD4 T-cell activation decreased slower in the +MVC arm. Absolute CD4 T-cell and CD8 T-cell counts, immune activation, CD4/CD8 T-cell ratio, and soluble inflammation markers were similar in both arms at the end of the study. CONCLUSION: Addition of maraviroc in early integrase inhibitor-based treatment of HIV-1 infection results in faster reduction of 2-LTR newly infected cells and recovery of CD4 T-cell counts, and a modest reduction in total reservoir size after 48 weeks of treatment. Paradoxically, CCR5 blockade also induced a slower decrease in plasma viremia and immune activation.

Predictive factors of radiation dose in ERCP: a prospective study in 2 tertiary centers.

BACKGROUND: The use of fluoroscopy to aid endoscopic retrograde cholangiopancreatography (ERCP) places both the patient and the endoscopy staff at the risk of radiation-induced injury. Previous reports have demonstrated a linear relationship between radiation dose and fluoroscopy duration. AIM: To identify predictive factors of fluoroscopy time and radiation exposure to patients undergoing ERCP by using pulsed fluoroscopy. METHODS: Four hundred and four consecutive ERCPs performed from January 2010 to November 2010 at 2 tertiary centers in Spain were prospectively studied. Patients and procedural variables were analyzed. Philips BV Pulsera mobile fluoroscopy system was used on the endoscopy unit. Entrance surface dose, dose-area product, and fluoroscopy time were recorded for each patient. RESULTS: A total of 404 ERCPs on 404 consecutive patients were studied (mean age 73 y). The average entrance surface dose and dose-area product were 12.0 mGy and 0.37 mGy/m2, respectively. Mean fluoroscopy time was 2.31 minutes. The biliary ducts were adequately visualized in 371 (92%) cases. After analysis with a univariable model, the factors found to significantly increase the radiation dose (P75>19.6 mGy) were as follows: alkaline phosphatase serum levels (P=0.047), balloon dilation (P=0.005), biliary stent placement (P=0.001), and ERCP diagnosis (P=<0.0001). In a multivariate analysis, only stent insertion significantly increased the radiation dose (risk ratio 4.75; 95% confidence interval, 1.84-7.63). CONCLUSIONS: In this prospective analysis, multiple factors affected the radiation dose. Stent insertion was the only independent predictor significantly associated with prolonged fluoroscopy.

Addition of metronidazole to azathioprine for the prevention of postoperative recurrence of Crohn's disease: a randomized, double-blind, placebo-controlled trial.

BACKGROUND: Endoscopic recurrence occurs in up to 80% of patients with Crohn's disease 1 year after intestinal resection. Imidazole antibiotics, thiopurines, and particularly their combination have proven efficacy in preventing endoscopic recurrence. The aim of the study was to compare the efficacy of the addition of metronidazole (for 3 months after the surgical treatment) to azathioprine for the prevention of postsurgical endoscopic recurrence. METHODS: A pilot study was made of 50 patients with Crohn's disease undergoing intestinal resection with ileocolic anastomosis and treated with 2 to 2.5 mg/kg of azathioprine per day for 1 year. The patients were randomized to receive additional 15 to 20 mg/kg of metronidazole per day or placebo for the first 3 months (n = 25 per arm). Endoscopic assessment was performed 6 and 12 months after the surgical resection. The primary end point was the prevention of endoscopic recurrence as defined by a Rutgeerts score of <2 at 6 months. The initial sample size had an 80% statistical power in detecting an absolute risk reduction of ≥30%. RESULTS: Endoscopic recurrence occurred in 28% and 44% of the patients at 6 months (P = 0.19) and in 36% and 56% (P = 0.15) at 12 months in the metronidazole and placebo groups, respectively. No statistically significant differences were found between the treatment groups regarding severe endoscopic recurrence (Rutgeerts score ≥ 3) at 6 and 12 months. Likewise, there were no differences in the rate of adverse events between the treatment groups. CONCLUSIONS: The addition of metronidazole to azathioprine did not significantly reduce the risk of endoscopic recurrence beyond azathioprine alone in this study but does not worsen its safety profile.

Colonoscopy in rats: An endoscopic, histological and tomographic study.

AIM: To describe colon anatomy with colonoscopy and computed tomography (CT) to develop a rat model for future studies of therapeutic colonoscopy. METHODS: Eighteen male Sprague-Dawley rats, on average 400-420 g, underwent total colonoscopy, CT and histological examination. Colonoscopy was performed after bowel preparation with a baby upper gastrointestinal endoscopy with an outer diameter of 6.7 mm. CT obtained a 3D image of total colon after a rectal enema with radiological contrast. Macroscopic and microscopic examinations were examined with a conventional technique (hematoxylin and eosin). Colonic wall thickness, length and diameter measurements were taken from the anus, 3, 7, 14 and 20 cm from the anal margin. RESULTS: The median colonoscope depth was 24 cm (range 20-28 cm). Endoscopic and tomographic study of colon morphology showed an easy access with tubular morphology in the entire left colon (proximal left colon and rectum). Transverse colon was unapparent on colonoscopy. Right colon, proximal to the splenic flexure, was the largest part of the colon and assumed saccular morphology with tangential trabecula. Radiological measurements of the colonic length and diameter substantiate a subdivision of the right colon into two parts, the cecum and distal right colon. In addition, histological measurement of the colonic wall thickness confirmed a progressive decrease from rectum to cecum. The muscular layer was thinner in the proximal left colon. CONCLUSION: The combination of colonoscopy, tomography and histology leads to a better characterization of the entire colon. These data are important for deciding when to perform endoscopic resections or when to induce perforations to apply endoscopic treatments.

Determination of the ideal preparation for colonoscopy in a rat model.

BACKGROUND: Quality bowel preparation is essential to examine the entire colon adequately. No trials comparing different purgative regimens are available in animal models. The aim was to compare 5 methods for bowel cleansing to develop a rat model to study therapeutic colonoscopy. METHODS: Twenty-five rats were assigned to one of 5 regimens: (1) high-volume polyethylene glycol electrolyte solution (HV-PEG-ES, 40 mL); (2) low-volume PEG-ES (LV-PEG-ES, 20 mL); (3) high-volume PEG-ES+ascorbic acid (HV-PEG-ES+AA, 20 mL); (4) LV-PEG-ES+AA, 10 mL; (5) rectal enema with saline solution (RE-SS). Bowel preparation quality was rated by total colonoscopy. RESULTS: RE-SS is the best regime for left colon cleansing, whereas HV-PEG-ES and HV-PEG-ES+AA solutions resulted in significantly better cleansing in the whole colon. HV-PEG-ES+AA regimen needed less volume, and administration was easier. CONCLUSIONS: A total of 20 mL of PEG-ES+AA before colonoscopy is the best regimen to explore the whole colon, whereas to explore the left colon RE-SS is adequate.

[Preparation for colonoscopy: types of scales and cleaning products]. / Preparación para colonoscopia: tipos de productos y escalas de limpieza.

Adequate bowel preparation is essential before a colonoscopy, allowing us to make a proper examination of the entire mucosa. The ideal method of colon cleansing should be fast, safe, and get a proper cleaning with minimal discomfort for the patient. Today we have a wide variety of colon cleansing products, information sometimes becomes confused. A good colon preparation depends partly on correct choice of the same, but also upon dietary restriction. Knowledge of all these products, with their advantages and limitations, we can make a better selection for each patient, and although the efficacy is comparable, is the experience of the browser, patient preferences, and the degree of compliance with the instructions preparation, which greatly influence the results.

[Endoscopic management of luminal stenosis in inflammatory bowel disease]. / Manejo endoscópico de las estenosis luminales en la enfermedad inflamatoria intestinal.

Luminal stenosis is frequent in Crohn's disease (CD) due to transmural involvement. Before any endoscopic treatment, the presence of neoplastic stenosis should always be excluded. Endoscopic balloon dilatation has been used in several series to treat benign stenosis, mainly in CD with involvement of the distal ileon, colon or surgical anastomosis, with success rates of 51% to 85%, although recurrence is high. The concomitant use of injected steroids (triamcinolone) after endoscopic dilatation produces longer-lasting results, but there are few published reports. In patients with luminal stenosis refractory to conventional endoscopy, three emerging techniques may be useful: self-expanding metallic stents, biodegradable endoprostheses and intralesional infliximab injection.

Long-term outcome of patients with distal ulcerative colitis and inflammation of the appendiceal orifice.

BACKGROUND AND AIMS: Skip inflammation of the appendiceal orifice has been described in distal UC (UC-IAO) but long-term clinical outcomes are poorly established. Our aim was to evaluate the long-term clinical outcomes of UC-IAO as compared to classic distal UC. METHODS: Patients with UC-IAO were identified from the local IBD database. Disease outcome and therapeutic requirements during follow-up were accurately collected, and compared with a control group of patients with distal UC without peri-appendiceal involvement matched by disease extent (proctitis/distal), smoking habit, and date and age at diagnosis. RESULTS: Fourteen UC patients were found to have UC-IAO, most of them with initial extent of UC limited to the rectum. All patients were initially managed with mesalazine administered orally (28.5%), topically (28.5%), or in combination (43%). After a median follow-up of 78 months (interquartile range--IQR 45-123) most UC-IAO patients were successfully managed with oral and/or topical aminosalicylates. Only one of them developed proximal disease progression. As compared to controls, no differences in clinical outcomes or therapeutic requirements were found. CONCLUSIONS: Patients with UC-IAO tend to present a mild course, with a low probability to develop proximal progression of disease extent or to require immunosuppressive therapy or colectomy.

Radiation dose to patients during endoscopic retrograde cholangiopancreatography.

Endoscopic retrograde cholangiopancreatography (ERCP) is an important tool for the diagnosis and treatment of the hepatobiliary system. The use of fluoroscopy to aid ERCP places both the patient and the endoscopy staff at risk of radiation-induced injury. Radiation dose to patients during ERCP depends on many factors, and the endoscopist cannot control some variables, such as patient size, procedure type, or fluoroscopic equipment used. Previous reports have demonstrated a linear relationship between radiation dose and fluoroscopy duration. When fluoroscopy is used to assist ERCP, the shortest fluoroscopy time possible is recommended. Pulsed fluoroscopy and monitoring the length of fluoroscopy have been suggested for an overall reduction in both radiation exposure and fluoroscopy times. Fluoroscopy time is shorter when ERCP is performed by an endoscopist who has many years experience of performing ERCP and carried out a large number of ERCPs in the preceding year. In general, radiation exposure is greater during therapeutic ERCP than during diagnostic ERCP. Factors associated with prolonged fluoroscopy have been delineated recently, but these have not been validated.