Efficacy and safety of transgastric closure in natural orifice transluminal endoscopic surgery using the OTSC system and T-bar sutures: a survival study in a porcine model

The Endoscopic Treatment of Iatrogenic Gastrointestinal Perforation

BACKGROUND

Iatrogenic gastrointestinal perforation is a life-threatening complication that arises very rarely in routine endoscopic procedures, with an incidence of 0.03-0.8%. It is more likely in highly complex and invasive therapeutic interventions. In certain situations, endoscopic closure of the perforation and treatment with antibiotics can obviate the need for emergency surgical repair.

METHODS

This review is based on pertinent articles retrieved by a selective literature search in PubMed and on a relevant position paper.

RESULTS

Existing clinical studies of treatment for iatrogenic gastrointestinal perforation are mainly retrospective and uncontrolled. No randomized and controlled trials have been performed to date. If the perforation is discovered soon after it arises, endoscopic treatment can be considered. Gastrointestinal perforations that are less than 30 mm in size can be closed with a clip. In the esophagus, expanding metal stents can be used as well. Clip application is successful in 80-100% of cases of gastrointestinal perforation, and the perforation remains permanently closed in 60-100% of cases. Reports on the endoscopic treatment of esophageal perforation show mixed results, with closure rates of roughly 90% and clinical success rates of roughly 80%. If endoscopic treatment is not possible, timely laparoscopic or open surgical repair is needed.

CONCLUSION

The endoscopic treatment of iatrogenic perforations is safe and reliable. Success depends on early detection, adequate endoscopic closure with properly mastered technique, and the early initiation of concomitant antibiotic treatment, which must be continued for a full course. Most patients who are treated in this way do not need emergency surgery.

Gastrotomy Healing After Transgastric Peritoneoscopy: A Randomized Study in a Pig Model

INTRODUCTION

Reliable closure and infection prevention are the main barriers for implementation of pure transgastric peritoneoscopy. The primary aim of this study was to assess healing of over the scope clip (OTSC) closed gastrotomies.

MATERIALS AND METHODS

Pure transgastric peritoneoscopy was performed in 7 pigs. The pigs were randomized to 14 or 28 postoperative days (POD) of follow-up. Decontamination of the access route was performed before instrumentation. A full necropsy was performed. Closure was evaluated with histopathological examination of excised gastrorrhaphies.

RESULTS

Three pigs were allowed 14 POD of follow-up, and 4 pigs were allowed 28 POD of follow-up. Survival was achieved in 6 of the 7 animals; 1 pig was euthanized due to diffuse peritonitis. Based on our definition, full-thickness healing had only been achieved in a single pig allowed 28 POD. With respect to clinical relevancy, full-thickness healing was deemed achieved in 4 of 6 pigs completing follow-up and in all pigs allowed and surviving 28 POD. Access required repeated punctures and the use of several endoscopic instruments.

CONCLUSIONS

Full-thickness healing of the gastrotomy was only found in a single case when adhering to the per protocol definition. Endoscopic ultrasonography-guided access was difficult. It lacks reproducibility and needs refinement. Despite a combined decontamination regimen, infectious complications still occurred.

Natural-orifice transluminal endoscopic surgery

BACKGROUND

Natural-orifice transluminal endoscopic surgery (NOTES) represents one of the most significant innovations in surgery to emerge since the advent of laparoscopy. A decade of progress with this approach has now been catalogued, and yet its clinical application remains controversial.

METHODS

A PubMed search was carried out for articles describing NOTES in both the preclinical and the clinical setting. Public perceptions and expert opinion regarding NOTES in the published literature were analysed carefully.

RESULTS

Two hundred relevant articles on NOTES were studied and the outcomes reviewed. A division between direct- and indirect-target NOTES was established. The areas with the most promising clinical application included direct-target NOTES, such as transanal total mesorectal excision and peroral endoscopic myotomy. The clinical experience with distant-target NOTES, such as for appendicectomy and cholecystectomy, showed feasibility; however, NOTES-specific morbidity was introduced and this represents an important limitation.

CONCLUSION

NOTES experimentation in the preclinical setting has increased substantially. There has also been a significant increase in the application of NOTES in humans in the past decade. Enthusiasm for NOTES should be tempered by the risk of incurring NOTES-specific morbidity. Surgeons should carefully consider patient preferences regarding this new minimally invasive option, as opinions are not unanimously supportive of NOTES. As technical limitations are overcome, the clinical application of NOTES is predicted to increase. It is paramount that, when this complex technique is performed on humans, it is applied judiciously by appropriately trained experts with outcomes recorded in a registry.

Natural orifice transluminal endoscopic surgery in humans: feasibility and safety of transgastric closure using the OTSC system

BACKGROUND

NOTES is a technique in which an operation is performed within the body without a skin incision by using a natural body orifice to provide access. The principal challenge of transgastric NOTES procedures is still the feasibility and safety of access closure. Currently, there are very limited data regarding the closure of transgastric NOTES in humans, and the standard method and device for closure has not been defined. Herein, we evaluate the feasibility and safety of gastric closure after NOTES procedures in humans with the over-the-scope clip (OTSC).

METHODS

Review of collected data of patients underwent transgastric NOTES in prospective clinical studies between April 2010 and March 2014 focused on the gastric closure with the OTSC.

RESULTS

A total of 43 patients underwent transgastric

NOTES

36 patients with an acute appendicitis, six patients with a prophylactic bilateral salpingo-oophorectomy, and one patient with uterus myomatosus. In all 43 cases, the incision of the gastric wall and the endoscopic access to the abdominal cavity succeeded without any difficulty. After performing transgastric procedures, it was possible to close the access by OTSC in all cases. There were all in all three adverse events: one major (Clavien-Dindo Grade III) and two minor (Clavien-Dindo Grades I and II).

CONCLUSION

Even if we could show for the first time in more than 40 consecutive patients that there is a safe approach for closing the transgastric access, it is absolutely necessary that further investigation in clinical settings has to be done to establish clear indications and guidelines for the use of transgastric NOTES.

Gastrojejunostomy by pure natural orifice transluminal endoscopic surgery using a newly designed anastomosing metal stent in a porcine model

BACKGROUND

The accepted palliative treatment for malignant gastric outlet obstruction (GOO) is surgical bypass or placement of self-expandable metal stents. We developed a safe and simple natural orifice transluminal endoscopic surgery (NOTES) technique for gastrojejunostomy using a fully covered, anastomosing metal stent in a porcine model.

METHODS

Under general anesthesia, 11 pigs underwent gastrojejunostomy with a 4 cm length anastomosing metal stent. After gastrotomy formation using a needle knife, the jejunum was drawn into the stomach with alligator forceps. A jejunotomy was then performed in the gastric cavity, which was followed by deployment of an anastomosing metal stent under fluoroscopic guidance. Next, the first portion of the duodenum was resected by an endoscopic linear stapler via laparoscopy, thereby creating the model of GOO. Oral feeding was resumed 24 h after the procedure, and animals were euthanized at 1, 2, and 4 weeks after the operation.

RESULTS

Side-to-side gastrojejunostomy was successfully completed through NOTES in 10/11 animals. Ten pigs stayed healthy until the planned sacrifice. The mean gastrojejunostomy procedure time was 41 min (range 15-94 min). By postmortem examination, anastomoses were still intact without intraperitoneal necrosis or adhesion. Histological examination revealed adequate submucosal apposition in all ten experimental pigs undergoing successful endoscopic gastrojejunostomy.

CONCLUSION

Creating a gastrojejunostomy by NOTES using an anastomosing metal stent seems to be a safe, feasible, durable, and reproducible method for GOO.

[Endoscopic submucosal dissection]

Endoscopic submucosal dissection (ESD) was developed in Japan but has now also become permanently established in various centers in Europe. ESD is an endoscopic en bloc mucosal resection technique for the treatment of early cancers with a diameter >1 cm and also superficial precancerous lesions, which could only be removed unsatisfactorily in several fragments or with uncertain lateral safety margins using previous loop excision procedures. Using ESD a lesion is excised after circular marking and generous submucosal injection with a safety margin of approximately 5 mm and subsequently resected at the level of the submucosa with a 1-3 mm short diathermic knife. ESD requires high technical skills in interventional endoscopy and is more time-consuming than snare resection techniques. However, numerous studies have shown a clear superiority for ESD with respect to the R0 resection rate and the local recurrence rate. The present article gives a current review of the use of ESD in the upper and lower gastrointestinal tract and demonstrates perspectives of the procedure.

Comparison of gastrotomy closure modalities for natural orifice transluminal surgery: a canine study

BACKGROUND

Reliable closure of the gastrotomy after transgastric natural orifice transluminal endoscopic surgery (NOTES) remains unresolved.

OBJECTIVE

To compare the technical aspects and clinical and histologic outcomes of NOTES gastrotomy closure techniques.

DESIGN

Experimental study.

SETTING

Animal laboratory.

PATIENTS

Thirty-four dogs, 14 for nonsurvival study and 20 for survival study.

INTERVENTIONS

The animals randomly received different gastrotomy closures after NOTES: endoclip, omentoplasty, over-the-scope-clip (OTSC), and hand-suturing.

MAIN OUTCOME MEASUREMENTS

Procedure time, closure strength, survival, postoperative adverse events, and histologic evaluation of wound healing.

RESULTS

Omentoplasty and OTSC groups needed shorter procedure times and fewer clips than the endoclip group. The endoclip and omentoplasty groups generated similar leakage pressures (34.5 ± 2.6 vs 42.2 ± 4.1 mm Hg, P > .05), both lower than OTSC and hand-suturing groups (81.5 ± 2.1 and 87.0 ± 3.0 mm Hg, respectively, P < .001). Of the 20 animals in the survival study (all 4 groups), only 2 of 6 in the endoclip group were killed prematurely due to sepsis. Necropsy revealed the OTSC group reached a 100% clip retention rate, higher than the endoclip (47.9%) and omentoplasty groups (44.4%, P < .05) rates. Complete healing, defined as intact and continuous gastric layers microscopically, was seen in 83.3% of animals (5 of 6) in the omentoplasty group, comparable with OTSC (4 of 6, 66.7%, P = .500) but higher than the endoclip group (1 of 6, 16.7%, P = .04).

LIMITATIONS

Animal study.

CONCLUSIONS

Omentoplasty is easier and safer for NOTES gastrotomy closure than endoclips and offers safety profile and efficacy similar to OTSC and hand-suturing.

The EURO-NOTES clinical registry for natural orifice transluminal endoscopic surgery: a 2-year activity report

BACKGROUND

The EURO-NOTES Clinical Registry (ECR) was established as a European database to allow the monitoring and safe introduction of Natural Orifice Transluminal Endoscopic Surgery (NOTES). The aim of this study was to analyze different techniques applied and relative results during the first 2 years of the ECR.

METHODS

The ECR was designed as a voluntary database with online access. All members of the European Society for Gastrointestinal Endoscopy and the European Association for Endoscopic Surgery were requested to participate in the registry. Demographic and therapy data as well as data on the postoperative course are recorded in the ECR in an anonymous way.

RESULTS

A total of 533 patients who underwent NOTES procedures were included in the study. Four different hybrid techniques for 435 cholecystectomies were described, registering postoperative complications in 2.8% of patients, addition of a single trocar in 5.3%, and conversions to laparoscopy in 0.5%. Both flexible endoscopic and rigid laparoscopic cholecystectomy techniques proved to be safe and effective with minor differences. There was a shorter operative time in the rigid laparoscopic group. Thirty-three appendectomies were reported by transgastric and transvaginal techniques, with transvaginal techniques scoring shorter operative time and hospital stay, but with a frequent need to add more trocars. Overall complications occurred in 14.7% of patients but they did not differ significantly among the different techniques. One transvaginal and 31 transanal sigmoidectomies were included for prolapse and diverticulitis, with four postoperative complications (12.5%), but none needing further treatment. Twenty peroral esophageal myotomies were included with three postoperative complications (15.0%), but none needing further treatment.

CONCLUSIONS

Five years since the introduction of NOTES into clinical practice, hybrid techniques have gained considerable clinical application. Several NOTES hybrid cholecystectomy and appendectomy techniques are practicable and safe alternatives to laparoscopic procedures. Also, sigmoidectomies and peroral esophageal myotomies were described, proving feasibility and safety. Nevertheless, the real benefit of NOTES for patients still needs to be assessed.

Performance of the OTSC System in the endoscopic closure of iatrogenic gastrointestinal perforations: a systematic review

BACKGROUND

Reliable closure is a prerequisite for conventional and innovative endoscopic procedures, such as NOTES. The purpose of this study is the systematic evaluation of the procedural and clinical success rates in closure of iatrogenic gastrointestinal perforations and acute anastomotic leaks by means of the over-the-scope-clip system (OTSC(®)).

DESIGN

PubMed and other sources were searched systematically for clinical and preclinical research on the evaluation of the OTSC System for closure of gastrointestinal perforations and leaks. Appraisal of studies for inclusion and data extraction was performed independently by two reviewers using an a priori determined data extraction grid. Major endpoints to be extracted were data on procedural success (successful clip application) and clinical access (durable closure of defect without secondary adjunct therapy).

RESULTS

A total of 17 clinical research articles/abstracts and 22 preclinical research articles/abstracts were identified. The examined clinical studies comprised case series and clinical single-arm studies. The reviewed studies revealed a consistently high mean rate of procedural success of 80-100 % and durable clinical success of 57-100 %. An identified major drawback preventing successful clip application was occurrence of fibrotic or inflamed lesion edges. Usage of the OTSC System was accompanied by neither major clip-related nor application-related complication. In experimental settings, closure of larger perforations and gastric access sites of NOTES or endoscopic full-thickness resection were achieved with high rates of success.

CONCLUSIONS

Because randomized, clinical trials are not available in this field of indication, the evaluation is based on small case series. Nevertheless, by pooling all experience gained, we conclude that endoscopic closure of iatrogenic gastrointestinal perforations and acute anastomotic leaks by means of the OTSC System is a safe and effective method.

Review and evaluation of methods correcting for population stratification with a focus on underlying statistical principles

When two or more populations have been separated by geographic or cultural boundaries for many generations, drift, spontaneous mutations, differential selection pressures and other factors may lead to allele frequency differences among populations. If these 'parental' populations subsequently come together and begin inter-mating, disequilibrium among linked markers may span a greater genetic distance than it typically does among populations under panmixia [see glossary]. This extended disequilibrium can make association studies highly effective and more economical than disequilibrium mapping in panmictic populations since less marker loci are needed to detect regions of the genome that harbor phenotype-influencing loci. However, under some circumstances, this process of intermating (as well as other processes) can produce disequilibrium between pairs of unlinked loci and thus create the possibility of confounding or spurious associations due to this population stratification. Accordingly, researchers are advised to employ valid statistical tests for linkage disequilibrium mapping allowing conduct of genetic association studies that control for such confounding. Many recent papers have addressed this need. We provide a comprehensive review of advances made in recent years in correcting for population stratification and then evaluate and synthesize these methods based on statistical principles such as (1) randomization, (2) conditioning on sufficient statistics, and (3) identifying whether the method is based on testing the genotype-phenotype covariance (conditional upon familial information) and/or testing departures of the marginal distribution from the expected genotypic frequencies.