Systems for liquid biopsy and/or drug delivery may include a capsule endoscope and a tether coupled to the capsule endoscope. The tether may include a flexible member with a lumen in fluidic communication with a port configured to permit passage of fluid, and the port may be, for example, on the capsule endoscope or the tether. In methods for liquid biopsy and/or drug delivery, the capsule endoscope may be advanced into a gastrointestinal tract of a patient, and navigated to a region of interest, where a patient sample may be withdrawn and/or a therapeutic substance may be administered through the lumen (e.g., through the port).
