Devices, systems, and methods for tissue resection

A system for tissue resection in a body lumen of a patient, the system comprising:

• an endoscope;
• a backstop delivery device extendable through the endoscope and positionable in the body lumen at a location of selected tissue for resection;
• a backstop including a covering deployable by the backstop delivery device;
• and
• a tissue resecting device extendable through the endoscope for resecting the selected tissue for resection;
• wherein the covering:
• is deployable to an outer surface of the body lumen;
• has one or more anchoring mechanisms disposed on an edge thereof and securable to the outer surface of the body lumen;
• is-expandable to cover the selected tissue for resection;
• and
• is configured, when expanded and secured to the body lumen, to define a space between the covering and the outer surface of the body lumen to provide clearance between the covering and the outer surface of the body lumen during tissue resection.