A medical catheter assembly and method of using the same. In one embodiment, the assembly comprises a gastrostomy feeding tube having a proximal end, a distal end and a longitudinal bore, the distal end being shaped to include an internal bolster, the internal bolster having an anchoring state and a non-anchoring state. A suture extends from the internal bolster through the longitudinal bore to exit the tube at its proximal end, proximal displacement of the suture maintaining the internal bolster in its anchoring state. A protective sleeve made of a rigid material is removably insertable into the tube through its proximal end, the suture being inserted through the protective sleeve. The protective sleeve, when inserted into the tube, serves to protect the suture from being cut when the tube is cut to a desired length after having been implanted in a patient.