A device for collecting a tissue sample includes an outer sheath extending longitudinally from a proximal end to a distal end and including a lumen extending therethrough. The device also includes a tissue collecting member movably housed within the lumen and biased toward an expanded configuration in which the tissue collecting member is curved about a longitudinal axis thereof and longitudinal edges thereof are separated from one another. The tissue collecting member is movable between a constrained position, in which the tissue collecting is received within the lumen and constrained by a surface thereof such that longitudinal edges of the tissue collecting member are drawn toward one another to define a channel therein, and a tissue collecting position, in which the tissue collecting member moves distally past the distal end of the outer sheath to revert to the biased expanded configuration to cut a target tissue into which it is inserted.