Major Leakage Research Articles

Endoscopic rescue of major anastomotic leakage

Endoscopic rescue of major anastomotic leakage

Postero-superior liver segments resection for benign tumors. Short-term results

Introduction: Indication for laparoscopic postero-superior liver segments resection in patients with benign tumors remains controversial. We aimed to evaluate the short-term results of minimally invasive resections (MILR) for benign tumors of postero-superior liver segments. Method: Data were accumulated since 2014 to 2018. Indications for liver resection were giant (>8 cm) growing lesions with clinical signs (abdominal pain on physical activity) and suspicion for malignancy. Result: Liver resection were performed in 75 patients. MILR were applied in 68 (91%), including 55 lap and 13 robotic resections. The benign lesions were presented by hemangioma (36), adenoma (13), FNH (12) and cystadenoma (7). Mean tumor size 8,8 cm (max 20 cm). Tumor size in 62% of cases was more than 8 cm. In 32 (47%) cases tumor adjoining to vessels. Partial resection of postero-superior segments and caudate lobe was performed in 25 (37%) patients. Robotic system was used in 8 of them. Open approach was applied only for 7 major hepatectomy (9%). Major morbidity after MILR of postero-superior segments was observed in 2 (2,9%) patient (IIIA, Clavien-Dindo): hematoma, after lap S6,7 resection and biloma after lap S3,4,8 resection, requiring additional drainage. There was no mortality. After major open liver resections bile leakage took place in 3 patients and required additional drainage. Mean operation time of MILR and open resection was comparable: 273 (160-490) min and 324 (260-395) min, respectively. The mean blood loss for MILR and open procedures was 300 (10-1000) ml and 1542 (100-4500) ml, respectively. The mean postoperative hospital stay after MILR and open resection was 6 (4-12) and 7(6-10) days, respectively. Conclusion: MILR for benign lesions located in postero-superior segments is the safe option for treatment of symptomatic and large benign tumors and may be considered as the first choice approach if surgery is indicated.

The learning curve for a surgeon in robot-assisted laparoscopic pancreaticoduodenectomy: a retrospective study in a high-volume pancreatic center.

Pancreaticoduodenectomy (PD) is one of the most technically difficult abdominal operations. Recent advances have allowed surgeons to attempt PD using minimally invasive surgery techniques. This retrospective study aimed to analyze the learning curve of a single surgeon who had carried out his first 100 robot-assisted laparoscopic pancreaticoduodenectomy (RPD) in a high-volume pancreatic center. The data on consecutive patients who underwent RPD for malignant or benign pathologies were prospectively collected and retrospectively analyzed. The data included the demographic data, operative time, estimated blood loss, postoperative length of hospital stay, morbidity rate, mortality rate, and final pathological results. The cumulative sum (CUSUM) analysis was used to identify the inflexion points which corresponded to the learning curve. Between 2012 and 2016, 100 patients underwent RPD by a single surgeon. From the CUSUM operation time (CUSUM OT) learning curve, two distinct phases of the learning process were identified (early 40 patients and late 60 patients). The operation time (mean, 418min vs. 317min), hospital stay (mean, 22days vs. 15days), and estimated blood loss (mean, 227ml vs. 134ml) were significantly lower after the first 40 patients (P < 0.05). The pancreatic fistula, postoperative hemorrhage, delayed gastric emptying, and reoperation rates also decreased in the late 60 patients group (P < 0.05). Non-significant reductions were observed in the incidences of major (Clavien-Dindo Grade II or higher) morbidity, postoperative death, bile leakage, gastric fistula, wound infection, and open conversion. RPD was technically feasible and safe in selected patients. The learning curve was completed after 40 RPD. Further studies are required to confirm the long-term oncological outcomes of RPD.

Sutureless Valve Replacement Through a Right Anterior Mini-thoracotomy in Elderly Patients With Stenotic Bicuspid Aortic Valve

Several indications for sutureless aortic valve replacement (SU-AVR) have been a matter of debate. We evaluated our experience with Perceval-S (LivaNova group, Saluggia, Italy) SU-AVR in patients with severe aortic stenosis (AS) involving bicuspid aortic valve (BAV), even though presence of BAV is still considered to be a contraindication for sutureless valves. From January 2013 through March 2018, 13 patients with severe AS involving BAV underwent SU-AVR with the Perceval-S (LivaNova group, Saluggia, Italy) prosthesis in a single center. Preoperative evaluation included coronary catheterization and multisliced computerized tomography was performed in all patients. Three-dimensional transthoracic echocardiography was used to evaluate for obtaining the anatomy and phenotype of BAV. Minimally invasive approach through right anterior thoracotomy from third intercostal space was performed for all patients. The mean age was 72.8 ± 2.26 years ranging from 70 to 77, and 53.8% (n = 7) were male. The mean aortic valve gradient decreased from 46.4 ± 13.8 to 13.6 ± 4.4 mmHg postoperatively. The mean aortic valve area increased from 0.69 ± 0.22 to 1.81 ± 0.38 cm2. There was no in-hospital mortality. One patient (7.6%) had third-degree atrioventricular block requiring permanent pacemaker implantation. Mean follow-up was 15.1 ± 6.3 months (maximum 2 years). No major paravalvular leakage or valve migration occurred postoperatively. This study shows that SU-AVR is a technically feasible and safe procedure in patients with severe AS and BAV with acceptable good surgical outcomes. Presence of BAV in AS should not be considered a contraindication to Perceval-S prosthesis (LivaNova group, Saluggia, Italy).

All microannuli are not created equal: Role of uncertainty and stochastic properties in well leakage prediction

Carbon Capture and Storage (CCS) as a method for climate mitigation relies on CO2 being locked up in subsurface reservoirs with a long-term perspective. Active and abandoned wellbores are among the major potential leakage paths for CO2, and their success as "gate keepers" relies on the quality of well cement. The length requirements and recommended practices for cement sheaths in active wells vary from country to country. In this study, we investigate how stochastic properties of the microannulus may affect the recommended "safe length " of cement sheath, should assigning such length be attempted for CO2 wells. We demonstrate, by means of a simple numerical model, that variation in the width of the microannulus along the well makes it a challenging task to assign a figure to the "safe cement-sheath length", even though longer cement sheaths do indeed reduce the risk of leakage. Variation in the mean value or standard deviation of the microannulus width by only 10% changes the recommended length of the cement sheath by up to an order of magnitude. This finding sheds new light on the use and added value of more accurate leakage prediction models: due to the uncertainties in and the lack of information about the properties of microannuli, such models should focus on investigating the effects of different operational and in-situ factors on the leakage potential rather than on attempting to accurately predict the leakage flow rate, however tempting such prediction exercise might seem at first glance.

PS01.083: NEGATIVE INTRALUMINAL PRESSURE FOR COMPLEX ESOPHAGEAL PERFORATIONS OR ANASTOMOTIC LEAKS

Abstract Background Dehiscence of esophago-gastric or esophago-jejunal anastomosis and spontaneous esophageal perforation are life threatening conditions due to the likelihood of breakdown following repair and the sequelae of sepsis. No unit has a large experience in the management of these problems and many approaches are described. Negative intraluminal pressure therapy (NIPT) is a method of minimally invasive operative management described by Berrisford and colleagues (Eur J Cardio-Thoracic Surg 33;2008;742–744). Despite its success, few institutions have reported on its use. Methods We reviewed our experience with the management of complex esophageal and anastomotic leaks and identified those that failed stenting, or where the diagnosis of major clinical anastomotic leaks was delayed. In this unit NIPT is the treatment of choice for these at risk patients. NIPT involves the open or endoscopic placement of an intra-luminal drainage tube with multiple side-holes, which is placed across the esophageal defect and brought through the stomach or jejunum and through the upper abdominal wall. A 10cm negative pressure of H20 is applied and the patency of the tube is maintained by the patient orally ingesting sterile water continuously. Nutrition may be provided parenterally or jejunally. Results Eleven patients were identified who were treated with NIPT for either esophageal perforation or delayed anastomotic failure over a 7 year period. Four patients had anastomotic leaks, 4 had iatrogenic perforations (2 failed stenting and 1 delayed diagnosis) and 3 had Boerhaave's syndrome. Of the 11 patients, 8 were male. Age ranged from 19–71 years. The median duration of drain application was 19 days. For 5 of the 11 patients, NIPT was combined with some degree of formal operative intervention. Operative video footage was taken and archived where possible. Complete restoration of the GI tract continuity was achieved in all patients. There was no significant procedural morbidity and there were no mortalities. Conclusion NIPT is a minimally invasive treatment option for complex esophageal/anastomotic leaks and we advocate its use, alone or as an adjunct to surgical intervention, in the above patient cohort. We have increasingly inserted the tube successfully under sedation alone, reducing the perioperative complications of general anaesthesia. Disclosure All authors have declared no conflicts of interest.

Direct Observation of Gate Leakage Paths in AlGaN/GaN High Electron Mobility Transistors by Electron Beam–Induced Current

In this study, the electron beam–induced current technique was used to investigate the spatial distribution of gate leakage paths in AlGaN/GaN high electron mobility transistors. The mesa-type devices exhibited three leakage paths: the mesa edge leakage, the sidewall leakage, and the isolation leakage. In mesa-isolated devices with a SiN passivation layer, the dominant leakage paths were through the SiN/GaN interface as a result of the imperfections at the SiN/semiconductor interface. The mesa sidewall leakage in a passivated device gradually decreased from the gate to the source/drain along the mesa edge. This was correlated with the diffusion length and the distance of the electron beam from the gate. In the device without a SiN passivation layer, the major leakage path was found to be through the mesa edge under the gate metal, which was induced by the gate-channel overlap at the mesa edge.

PS01.174: AN EXAMINATION OF OUTCOMES AFTER ANTE-THORACIC ROUTE WITH RIGHT HEMICOLON RECONSTRUCTION AFTER ESOPHAGECTOMY.

Abstract Background In our institute, we usually use gastric tube for reconstruction organ after esophagectomy. When we can’t use gastric tube, we use right hemi-colon with ante-thoracic route. Previously, we reconstructed by 1-step after esophagectomy, but from 2012, we have done by 2-step for reduce postoperative complications. Methods We enrolled 15 esophageal cancer patients who underwent esophagectomy and right hemicolon reconstruction between April 2004 and December 2016. Results The average age of 15 patients is 67.3. The reasons of using right hemicolon are as follows; post gastrectomy 13, stomach double cancer 2. The reasons of gastrectomy are as follows; gastric cancer 8, duodenum cancer 1, gastric ulcer 4. The average duration from gastrectomy to esophagectomy is 12.5 year. We reconstructed by 1-step for 5 patients, and after 2012, we reconstructed by 2-step for 10 patients. Anastomotic leakages were found in 2 cases (40.0%) in 1-step reconstruction group, and 3 cases (20.0%) in 2-step reconstruction group. In 1-step reconstruction group, 1 case occurred multiple anastomotic leakages and DIC, and another 1 case was found necrosis of reconstructive colon. In 2-step reconstruction group, we found 1 case of major leakage and 1 case of recurrent nerve paralysis and 2 cases of postoperative pneumonia. However, there were no case of tracheotomy. The incidence of pneumonia did not differ between the two groups. And the term of postoperative oral intake tend to shorter in 2-step reconstruction group (P = 0.06). 2 severe postoperative complications (Clavian-Dindo V or IVa) cases were found in 1-step reconstruction group, on the other hand, 2 cases severe complications (CD IIIa) in 2-step reconstruction group. Conclusion In the case of using right hemicolon as a reconstructive organ, 2-step reconstruction approach is useful and superior from the viewpoints of postoperative complications. Disclosure All authors have declared no conflicts of interest.

Experimental values for adjusting an automatic control valve in gas pipeline transportation

When a natural gas pipeline ruptures, the adjacent automatic line control valves (ALCVs) should close quickly to prevent leakage or explosion. The differential pressure set point (DPS) at each valve location is the main criteria for value setting in ALCV action. If the DPS is not properly adjusted, the ALCV may mistakenly close or it may not take any action at proper time. This study focused on the DPS values prediction for setting ALCV installed on a gas pipeline with 1mm orifice diameter. The effect of characteristic parameters such as pipeline operational pressure (POP) and pipeline pressure drop rate (ROD) due to rupture or major leak was experimentally investigated on DPS. Twenty-five different conditions with double set of typical mentioned characteristic parameters were chosen. For each condition, the differential pressure (DP) was measured over 180 seconds by analyzing the experimental values. Therefore, 25 maximum DP values (DPSs) were obtained. The DPS increases by increase in ROD or decreasing POP parameters. Because of using nitrogen gas instead of natural gas due to safety reasons, the DPS results can be practically applied by adding a safety factor of 15%. The diagram of DPS with respect to ROD and non-dimensional DPS (DOP) versus non-dimensional ROD (RTP) was provided for different POPs.

One-year outcomes associated with a novel stented bovine pericardial aortic bioprosthesis

ObjectivesThe study objectives were to evaluate the safety, effectiveness, and hemodynamic performance of a new stented bovine pericardial aortic valve. MethodsThis trial enrolled patients with symptomatic moderate or severe aortic stenosis or chronic, severe aortic regurgitation. We assessed death, valve-related adverse events, functional recovery, and hemodynamic performance at discharge, 3 to 6 months, and 1 year, as required by the US Food and Drug Administration for regulatory approval. The primary analysis compared late linearized rates of valve-related adverse events after implantation with Food and Drug Administration–specified objective performance criteria to determine whether the adverse event rates associated with the valve are within acceptable limits. Adverse events included thromboembolism, thrombosis, all and major hemorrhage, all and major paravalvular leak, and endocarditis. ResultsThe primary analysis included 864 patients who received an implant and 904.1 valve-years of follow-up. A total of 577 patients completed the 1-year evaluation. The primary end point was met for death, thromboembolism, thrombosis, all and major paravalvular leak, and endocarditis, but not for all and major hemorrhage. At 1 year, freedom from all death and from valve-related death was 96.4% and 99.7%, respectively. From baseline to 1 year, New York Heart Association class changed as follows: I, 10.8% to 73.7%; II, 48.9% to 22.6%; III, 38.0% to 3.5%; and IV, 2.3% to 0.2%. Effective orifice area increased from 0.9 ± 0.5 to 1.5 ± 0.4 (P < .0001), and mean aortic gradient decreased from 42.7 ± 16.5 to 12.5 ± 4.3 (P < .0001). ConclusionsThis analysis of a new stented bovine pericardial aortic valve demonstrated low overall mortality and valve-related adverse events, and hemodynamic performance comparable to that of other surgical aortic valves.

Transanal total mesorectal excision for rectal cancer: evaluation of the learning curve.

Transanal total mesorectal excision (TaTME) provides an excellent view of the resection margins for rectal cancer from below, but is challenging due to few anatomical landmarks. During implementation of this technique, patient safety and optimal outcomes need to be ensured. The aim of this study was to evaluate the learning curve of TaTME in patients with rectal cancer in order to optimize future training programs. All consecutive patients after TaTME for rectal cancer between February 2012 and January 2017 were included in a single-center database. Influence of surgical experience on major postoperative complications, leakage rate and operating time was evaluated using cumulative sum charts and the splitting model. Correction for potential case-mix differences was performed. Over a period of 60months, a total of 138 patients were included in this study. Adjusted for case-mix, improvement in postoperative outcomes was clearly seen after the first 40 patients, showing a decrease in major postoperative complications from 47.5 to 17.5% and leakage rate from 27.5 to 5%. Mean operating time (42min) and conversion rate (from 10% to zero) was lower after transition to a two-team approach, but neither endpoint decreased with experience. Readmission and reoperation rates were not influenced by surgical experience. The learning curve of TaTME affected major (surgical) postoperative complications for the first 40 patients. A two-team approach decreased operative time and conversion rate. When implementing this new technique, a thorough teaching and supervisory program is recommended to shorten the learning curve and improve the clinical outcomes of the first patients.

An experimental study of the effective parameters on automatic line-break control valves action in natural gas pipelines

The automatic line-break control valve (LBV) is a robust self-contained pipeline monitoring system which is widely used to prevent gas releasing upon rupture or large leakage event in the oil and gas pipelines. The differential pressure set point (DPS) at each valve location is the main criteria for value setting in LBV action. If the DPS is not properly adjusted, the LBV may mistakenly close or it may not take any action at proper time. In this study, the effect of characteristic parameters such as orifice diameter (OD), pipeline operational pressure (POP) and pipeline pressure drop rate (ROD) due to rupture or major leak was experimentally investigated on DPS. 100 different conditions with triple set of typical mentioned characteristic parameters were chosen. For each condition, the differential pressure (DP) was measured over 180 s by statistically analyzing the experimental results. Therefore, 100 maximum DP values (DPSs) were obtained. The attainable time to DPS depends only on OD and is independent of the POP and ROD and decreases by increasing the OD. The DPS increases by increase in ROD or decreasing OD or POP parameters. Because of using nitrogen gas instead of natural gas due to safety reasons and the uncertainties, the DPS results can be practically applied by adding a safety factor of 10%–15%. Finally, the diagram of DPS with respect to ROD was provided for different POPs and ODs. The diagram can be used as a basis for designing and regulating of LBVs installed on gas transportation pipelines.

Non-contrast MR imaging of blood-brain barrier permeability to water.

Many brain diseases are associated with an alteration in blood-brain barrier (BBB) and its permeability. Current methods using contrast agent are primarily sensitive to major leakage of BBB to macromolecules, but may not detect subtle changes in BBB permeability. The present study aims to develop a novel non-contrast MRI technique for the assessment of BBB permeability to water. The central principle is that by measuring arterially labeled blood spins that are drained into cerebral veins, water extraction fraction (E) and permeability-surface-area product (PS) of BBB can be determined. Four studies were performed. We first demonstrated the proof-of-principle using conventional ASL with very long post-labeling delays (PLD). Next, a new sequence, dubbed water-extraction-with-phase-contrast-arterial-spin-tagging (WEPCAST), and its Look-Locker (LL) version were developed. Finally, we demonstrated that the sensitivity of the technique can be significantly enhanced by acquiring the data under mild hypercapnia. By combining a strong background suppression with long PLDs (2500-4500 ms), ASL spins were reliably detected in the superior sagittal sinus (SSS), demonstrating the feasibility of measuring this signal. The WEPCAST sequence eliminated partial voluming effects of tissue perfusion and allowed quantitative estimation of E = 95.5 ± 1.1% and PS = 188.9 ± 13.4 mL/100 g/min, which were in good agreement with literature reports. LL-WEPCAST sequence shortened the scan time from 19 min to 5 min while providing results consistent with multiple single-PLD acquisitions. Mild hypercapnia increased SNR by 78 ± 25% without causing a discomfort in participants. A new non-contrast technique for the assessment of global BBB permeability was developed, which may have important clinical applications.

Major leak during controlled ventilation due to faulty exhaust valve missed during pre-use machine check.

Major leak during controlled ventilation due to faulty exhaust valve missed during pre-use machine check.

Early Postoperative Complications of Thoracic Esophageal Diverticula: A Review of 10 Cases from "Saint Mary" Hospital, Bucharest, Romania.

This is a retrospective case series study of 10 patients who underwent diverticulectomy for thoracic (epiphrenic or mid-esophageal) diverticula. It was recorded: main preoperative symptoms, usual blood tests, barium swallow, upper endoscopy and esophageal manometry. We analyzed the postoperative complications, length of stay in hospital and intensive care unit. Results: Most patients presented with regurgitation and/or dysphagia. The surgical approach was through left thoracotomy or abdominal for epiphrenic diverticula and through right thoracotomy or thoracoscopy for mid-esophageal diverticula. 4 patients had severe complications: 3 had major leaks (one death) and one had chylothorax. Surgery for thoracic diverticula is associated with high mortality and morbidity rates. Leak from the suture line is the most common complication, unlike chylothorax which is a rare complication. Conclusions: Thoracic diverticula represent a benign pathology which can have "žmalignant" postoperative complications. A thorough preoperative work-up is mandatory for choosing the appropriate surgical technique. Use of multiple cartridges for stapling suture increase the risk of leakage, but oversewing the suture may diminish it.

Critical view of safety faster and safer technique during laparoscopic cholecystectomy?

Objective:Incidence of Bile Duct Injuries (BDI) during Laparoscopic Cholecystectomy (LC) is reported to be higher as compared to Open Cholecystectomy. Studies have shown varying degree of success in reducing BDI by using Critical View of Safety (CVS) technique before clipping and cutting any structure. In this study, we will see whether CVS technique is faster and safer compared to conventional infundibular technique.Methods:This comparative study was conducted on patients who presented to Surgical Out-Patient-Department (OPD) of Khyber Teaching Hospital from July 2015 to June 2016. Total of 438 patients were divided into two groups. Group-A in which LC was done using infundibular while in Group-B, CVS technique was utilized. Two groups were compared for operating time and BDI.Results:The operative time was significantly reduced for LC using CVS technique (50 mins vs. 73 mins). Minor leaks were comparable (0.5% vs. 0.9%) but there was a significant difference in major LEAKS between the two techniques (0.5% vs. 1.4%).Conclusion:Although the “critical view of safety” requires more dissection as compared to infundibular technique, but once learnt and mastered, it is faster and safer identification technique during laparoscopic cholecystectomy.

Comparison of Complication Rate Between LeFort III and Monobloc Advancement With or Without Distraction Osteogenesis.

LeFort III osteotomies or monobloc advancements, with or without distraction, can be used to treat mid-facial hypoplasia causing exorbitism and obstructive sleep apnea in syndromic patients. This report is a meta-analysis of the complication rates following LeFort III osteotomies or monobloc advancement with or without distraction. Triple database search was conducted to identify articles addressing mid-facial hypoplasia treated with LeFort III or monobloc in which complications were detailed. Complications were considered major if they required a second operation or were potentially life threatening. Statistical analysis was performed with Student t test. Fifteen studies fit inclusion criteria. This yielded 363 total patients. In patients treated with a monobloc advancement, there was a statistically higher rate of major (P < 0.0001) and minor (P < 0.0001) complications, death (P = 0.02), cerebrospinal fluid (CSF) leaks (P < 0.0001), and meningitis/abscess (P < 0.0001) when distraction was used. In patients treated with a LeFort III, there was a statistically higher rate of reoperation when distraction was used (P = 0.001). In patients treated without distraction, there was a statistically higher rate of major (P < 0.0001) complications, death (P = 0.008), CSF leaks (P = 0.003), and reoperation (P < 0.0001) with a monobloc and a statistically higher rate of minor complications (P < 0.001) with a LeFort III. LeFort III proved to be a safer technique for the treatment of mid-facial hypoplasia. Although distraction was initially introduced to reduce complications, in this review, monobloc with distraction had the highest rate of major complications. There are multiple confounding factors that influence success of mid-face surgery and every patient must be evaluated and treated individually.

Evolution of neck dissections performed in conjunction with transoral robotic surgery lateral oropharyngectomy

Background: Two complications of transoral robotic surgery (TORS) lateral oropharyngectomy performed with neck dissection are hemorrhage and salivary leak. This study investigates the effect of neck dissection timing, and use of vessel ligation and muscle patch techniques, on the incidence of these complications. Methods: A retrospective case review was conducted on 33 patients who underwent TORS lateral oropharyngectomy and ipsilateral neck dissection for tonsillar SCC in one tertiary medical center. A technique for vessel ligation and prophylactic orocervical repair is described. Results: Eight patients (24%) underwent neck dissection prior to TORS, 19 patients (58%) had concurrent neck dissection with TORS, and six patients (18%) had a neck dissection following TORS. Of the 33 patients included, one had major haemorrhage and one developed a post-operative leak. Conclusions: Neck dissection prior to TORS is feasible, enabling selective arterial ligation and digastric flap insertion, but further studies are required to confirm if this significantly reduces the incidence of major secondary haemorrhage and salivary leaks.

Analysis on Risk of Multi - factor Disaster and Disaster Control in Oil and Gas Storage Tank

Abstract As a storage area of dangerous chemicals, oil and gas storage areas are prone to major leakage, fire and explosion accidents. In order to study the multi-factor catastrophic effect of the oil and gas storage tank under the influence of the domino accident, the non-linear relationship between the various disaster factors in the oil and gas storage tank area is obtained through the analysis of the multi-factor cooperative coupling in other research fields. The accident scene is based on the evolution of the scene, the establishment of Bayesian network based on multi-factor disaster accident model. Based on the actual case and the established model, the risk of disaster control in the oil and gas storage tank area is analyzed. The results show that the accident propagation path can be effectively cut off, the various hazard factors can be reduced and the probability of accident occurrence can be reduced.

Reducing Costs of Well Plugging and Abandonment While Verifying Risk

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 27921, “Risk-Based Approach to Well Plugging and Abandoning: Reducing Costs While Verifying Risk,” by Pedram Fanailoo, David Buchmiller, Simon Ouyang, and Eric Allen, DNV GL, prepared for the 2017 Offshore Technology Conference, Houston, 1–4 May. The paper has not been peer reviewed. Copyright 2017 Offshore Technology Conference. Reproduced by permission. A risk-based approach to well plugging and abandonment (P&amp;A) has been developed and successfully applied. The recommended method is based on research that allows the modeling of fluid flow through microcracks through a range of failure modes in downhole components, the determination of the effect on the environment through dispersion modeling, and identification of the basis for acceptance criteria. The complete paper describes how various P&amp;A designs can be compared by use of a risk methodology that takes account of degradation mechanisms, potential flow rates, and the effect on the environment. Introduction The application of the proposed method to fields suggests that alternative plugging solutions with fewer barriers than prescribed by the standard NORSOK D-010 guidelines result in the same low level of environmental risk. The method accounts for uncertainty related to input parameters and can be refined further if these uncertainties are reduced over time by field observations and testing. The proposed approach to quantifying the environmental risk associated with minor, long-term leakage from P&amp;A barriers, overburden formations, and natural seepage is to frame the issue in terms of potential modifications to valued environmental resources. This permits a degree of differentiation between alternative plugging designs, none of which may be physically capable of leading to the type of major leakage treated by standard environmental-risk-analysis approaches. Description of Well-Abandonment Designs General. Per NORSOK D-010, a P&amp;A job should be planned and performed with an eternal perspective. Numerous regulations and requirements for different countries and areas of operation exist, but these generally state that there should be at least one permanent well barrier between a potential source of inflow and the surface. A potential source of inflow is defined in the guideline as a formation with permeability, but not necessarily a reservoir. This requirement does not apply to the case in which the formation is a reservoir, with a reservoir defined as a permeable formation or group of formation zones originally within the same pressure regime, with a flow potential or hydrocarbons present or likely present in the future; in this case, the requirement is two permanent well barriers. These requirements can lead to confusion because NORSOK D-010 does not provide any further explanation of the terms “in-flow” and “flow potential.” Some major operators define “flow potential” as a formation with permeability and over-pressure, meaning that a reservoir can be a formation containing hydrocarbons, a formation with permeability and overpressure, or a combination of both. Furthermore, NORSOK D-010 holds that the last openhole section of a wellbore should not be abandoned permanently without installation of a permanent well barrier, often known as the surface P&amp;A barrier.