Catheters including guidewire tubes having a limited length and methods of using the catheters are described. The catheters may be delivered over guidewires in procedures that are commonly referred to as rapid-exchange delivery. In some embodiments, the catheters may be miniature flexible thrombectomy catheters that may be used to remove thrombus or other unwanted material from a body blood vessel or other small regions of body cavities in which the distal portion of the catheter has smaller external dimensions than the larger proximal portion.