Organ walls are composed of several layers: the mucosa (the surface layer), the submucosa, the muscularis (muscle layer), and the serosa (connective tissue layer). In gastrointestinal, colonic, and esophageal cancer, e.g., small polyps or cancerous masses may form along the mucosa and often extend into the lumens of the organs. Conventionally, this condition is treated by cutting out a portion of the affected organ wall. This procedure, however, may cause discomfort to patients, and pose health risks. Recently, physicians have adopted a minimally invasive technique called endoscopic mucosal resection (EMR), and another called endoscopic submucosal dissection (ESD), which removes the cancerous or abnormal tissues (e.g., polyps), keeping the walls intact. EMR may also assist in removing any undesired tissue, even if such tissue is not abnormal or diseased. For purposes of this disclosure, the term “lesion” or “abnormality” includes, and will be used to refer to, these cancerous or abnormal tissues generally.
EMR and ESD are generally performed with an endoscope, which may be a long, narrow elongate member optionally equipped with a light, imaging device, and other instruments and defining a lumen extending from a proximal to a distal end of the elongate member. During ESD, the endoscope is passed down the throat or guided through the rectum to reach an undesired tissue, such as a polyp, in an affected organ. The distal end of the endoscope, typically equipped with a hood carrying dissecting tools such as a small wire loop, a band, or a knife is guided towards the undesired tissue. For EMR, the undesired tissue may be drawn into the hood. This may be achieved by applying suction through working channel extending along the lumen, or by retracting a retraction tool that is extendable from the endoscope. When the undesired tissue is sufficiently drawn into the hood, the dissecting tool may dissect portions of the tissue or resect target tissue from the organ wall. Subsequently, the excised tissue may be extracted for examination, biopsy, or disposal.
For ESD, the hood is typically used to create a working volume, applying tissue tension for endoscopic instruments, and preventing extraneous tissue and debris from interfering with the operator's visualization and operation.
Conventional endoscopic hoods may provide sufficient volume to operate on, e.g., small areas of target tissue (˜smaller than 30 mm), but prove insufficient for dissecting, e.g., larger areas of target tissue (˜larger than 30 mm). The volume offered by conventional hoods is not sufficient to effectively grasp and resect larger tissue area, such as, e.g., large lesions. As a result, certain large lesions may not be resected properly, forcing the operator to perform the procedure multiple times. Numerous attempts, along with increased operation time, increase the risk of damaging the submucosal wall and causing irreparable damage to the surrounding tissue.