An apparatus for accessing a bodily passageway includes: an endoscope including an insertion portion configured to inserted into the bodily passageway; a drive tube including a lumen configured to receive the endoscope; a helically-wound thread disposed on an outer wall of the drive tube and configured such that rotation of the drive tube causes the drive tube with the endoscope to move along the passageway; a flexible drive shaft configured to transfer rotary motion generated by a power supply; and a rotatable drive collar disposed on the endoscope and configured to rotate the drive tube relative to the endoscope, the rotatable drive collar including a stator, a rotor rotatable over the stator and detachably coupled to the drive tube, a rotary gear configured to transfer the rotary motion from the flexible drive shaft to the rotor to rotate the drive tube, and a watertight seal disposed between the stator and the rotor.