A dilator comprises a guide extending through a tube, and a slidable sleeve exterior to the tube, such that a slit in the tube extending from a first end of the tube to a second end of the tube, opposite of the first end, is closed by a force applied via the slidable sleeve. When closed, the slit does not interfere with the tube being used as a dilator to dilate tissues of a patient through which the guide extends. When opened, the slit allows the tube to be placed onto the guide or removed from the guide.
