V. Raman Muthusamy, MD, MAS, FACG, AGAF, FASGE, Medical Director of Endoscopy, U CLA Health System
Endoscopy has undergone an incredible transformation over the past two decades. Previously, with the exception of endoscopic therapy for GI bleeding, removal of small to medium-sized polyps of the GI tract, and therapeutic ERCP, it was a primarily diagnostic technique that focused on imaging and tissue acquisition. Over the past twenty years, numerous advances have been made in the diagnostic and especially the therapeutic capabilities of these procedures. In my opinion, these advances primarily have centered on six major areas: (1) improved tissue resection techniques that facilitate the removal of early-stage tumors in one or more pieces; (2) submucosal or “third space” endoscopy techniques that have allowed for resection of subepithelial lesions and performance of myotomies to treat Zenker’s diverticulum, achalasia and gastroparesis; (3) interventional endoscopic ultrasound procedures that have played important roles in treating benign and malignant conditions, especially involving the pancreas; (4) the development of bariatric endoscopy techniques to facilitate primary weight loss or treat weight regain after prior bariatric surgery; (5) artificial intelligence to detect and interpret lesions of the GI tract; and (6) improvements in reprocessing of endoscopes, especially duodenoscopes, along with the development of single-use endoscopes.
Recently, advanced tissue resection techniques including endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) that have allowed the removal of large polyps, flat areas of focal dysplasia, and even early-stage cancers. ESD, in particular, allows for the removal of large lesions in one piece, so the assessment of margins and accurate tumor staging, if cancer is present, is possible. The information provided with these specimens is comparable to a surgically acquired specimen. These techniques have transformed our management of dysplastic Barrett’s esophagus, early-stage esophageal and gastric cancers and markedly reduced the need for surgical resections for large colon polyps. Future advances should focus on improving the speed and ease at which ESD can be taught and performed as well as achieving adequate reimbursement for this technique.
Submucosal or “third space” endoscopy involves accessing the third layer of the gastrointestinal wall by making an incision into the mucosa and creating a tunnel in the wall of the GI tract. The endoscope is advanced into this tunnel, and from this space, lesions in the wall of the GI tract such as gastrointestinal stromal tumors and neuro-endocrine tumors can be dissected and safely removed without the need for surgery. In addition, the muscle wall of the GI tract can be cut to treat diseases associated with increased muscle contractility such as Zenker’s diverticula, achalasia, and gastroparesis. Once the lesion is removed, or the muscle has been cut, the endoscope is removed, and the mucosal incision is sealed with endoscopic clips, allowing the ability to perform what were previously surgical procedures entirely with an endoscope.
Interventional endoscopy initially began with the injection of medications into the celiac plexus to relieve pain in the upper abdomen, primarily related to pancreatic cancer. However, the field has been transformed by the development of lumen-apposing metal stents (LAMS), which allow safe communication between two spaces/lumens to be created. This has led to markedly simplified and improved drainage of inflammatory pancreatic fluid collections (the FDA approved indication) as well as off-label, but widely utilized, applications. These include the drainage of infected gallbladders into the small bowel in patients who are poor candidates for surgery, internal drainage of obstructed biliary systems in patients with malignant obstruction and a prior failed ERCP procedure and by bypassing obstruction of the duodenum in patients with pancreas/duodenal cancers by the creation of gastrojejunostomies. This technology has allowed endoscopists to provide surgical quality bypasses/ drainages via procedures that typically take less than 30 minutes and represent arguably the greatest advance in endoscopic therapeutics over the past two decades.
Bariatric endoscopy initially focused in large part on treating complications associated with surgical bariatric procedures including sealing post-operative leaks with suturing or endoscopic stenting, managing stenoses with dilations and treating weight regain with pouch or outlet reduction procedures. More recently, primary endoscopic bariatric technologies, including the insertion of space-occupying balloons/objects and primary endoscopic sleeve gastroplasty, have been developed. While recent adverse events have raised concerns about the use of some balloons, there is great enthusiasm in developing a primary endoscopic bariatric technology given the prevalence of obesity in our US population. However, the optimal/ preferred technique has yet to be developed/determined. It is likely that this may be the area for greatest growth in therapeutic endoscopy should a safe, effective and durable endoscopic procedure be developed in the future.
In addition to the advances in therapeutics mentioned above, many advances in optics including zoom magnification and optical chromo endoscopy have allowed for markedly improved visualization that can potentially aid in detecting focal areas of abnormal tissue such as dysplasia or early cancer. These advances in imaging technology, coupled with artificial intelligence, should allow endoscopists to identify and assess lesionsin a fashion not previously possible. In the future, not only does AI have the potential to notify endoscopists if an area of the GI tract was not well visualized to trigger a re-examination, it can identify subtle lesions that may be missed by the endoscopist. Furthermore, the potential to use this technology to examine the mucosa of the lesion and the surrounding area may allow for an assessment of the risk of malignancy. This information could be used by endoscopists to determine which choice of the resection techniques described above may be most appropriate or whether surgery will be required due to the presence of advanced/invasive disease. AI may also be used to reduce radiation exposure during endoscopic procedures that require fluoroscopy as well as perform initial interpretations of capsule endoscopies to improve accuracy and reduce the reading times associated with these procedures.
Finally, multiple recent reports that found that reprocessed duodenoscopes could transmit multidrug-resistant bacteria between patients even when no breaches in reprocessing protocol occurred have led to a great deal of innovation in endoscope reprocessing. These have included a variety of tests to determine if an endoscope is contamination-free as well as research into developing low-temperature sterilization techniques that could be applied to all endoscopes. In addition, duodenoscopes with disposable tips and elevators have been developed. Most recently, a completely disposable single-use duodenoscope has been developed and is commercially available. Previously, a single-use colonoscope was developed but not widely adopted in part because its operating characteristics were somewhat different than existing devices. These developments suggest the feasibility of the concept of single-use devices. With time, if these devices can be made affordably and recycled, they may take hold. This could also aid in ergonomics as scopes with handles of different sizes, R and L handed versions, as well as variable weights and shaft stiffness, could be developed. These advances could hopefully ameliorate the rapidly rising incidence of endoscopy related musculoskeletal and joint injuries amongst endoscopists.
In conclusion, endoscopy has expanded from a primarily diagnostic modality into a minimally invasive modality that can achieve results comparable to minimally invasive or open surgical techniques. While recent advances in endoscopy have focused on the advances in diagnostics, therapeutics and reprocessing noted above, additional future innovation in the field will likely expand on the aforementioned areas as well as focus on an increasing number of vascular applications and the direct delivery of anti-tumoral agents to precisely and focally treat GI cancers.
Hesham Abboud, MD, PhD, Director of the Multiple Sclerosis and Neuroimmunology Program and staff neurologist at the Parkinson’s and Movement Disorder Center at University Hospitals of Cleveland, Case Western Reserve University School of Medicine