A catheter assembly, comprising: a catheter adapter comprising a distal end having a catheter hub, a proximal end opposite the distal end, and an inner lumen extending therebetween; a catheter coupled to the catheter hub and comprising a first end positioned within the inner lumen, and a second end extending distally from the distal end of the catheter adapter, the first end having a first inner diameter and the second end having a second inner diameter that is less than the first inner diameter; a cannula comprising a distal tip, a proximal end opposite the distal tip, and a tubular shaft extending therebetween, a first portion of the tubular shaft that extends to the distal tip having a first outer diameter and a second portion of the tubular shaft that extends to the proximal end of the cannula having a second outer diameter that is greater than the first outer diameter, the second outer diameter of the second portion being greater than the second inner diameter of the catheter and less than the first inner diameter of the catheter, and the first outer diameter of the first portion being less than the first and second inner diameters of the catheter, such that the cannula is configured to slidably insert within the first and second ends of the catheter, wherein a tapered third portion of the elongated tubular shaft is disposed between the first and second outer diameters; and a cannula shield coupled to the proximal end of the cannula and selectively coupled to the proximal end of the catheter adapter, the proximal end of the catheter adapter having an inner diameter that is greater than the second outer diameter of the cannula such that the cannula and cannula shield are capable of being entirely removed from the catheter and catheter adapter, respectively, and disposed following catheterization. a catheter adapter comprising a distal end having a catheter hub, a proximal end opposite the distal end, and an inner lumen extending therebetween; a catheter coupled to the catheter hub and comprising a first end positioned within the inner lumen, and a second end extending distally from the distal end of the catheter adapter, the first end having a first inner diameter and the second end having a second inner diameter that is less than the first inner diameter; a cannula comprising a distal tip, a proximal end opposite the distal tip, and a tubular shaft extending therebetween, a first portion of the tubular shaft that extends to the distal tip having a first outer diameter and a second portion of the tubular shaft that extends to the proximal end of the cannula having a second outer diameter that is greater than the first outer diameter, the second outer diameter of the second portion being greater than the second inner diameter of the catheter and less than the first inner diameter of the catheter, and the first outer diameter of the first portion being less than the first and second inner diameters of the catheter, such that the cannula is configured to slidably insert within the first and second ends of the catheter, wherein a tapered third portion of the elongated tubular shaft is disposed between the first and second outer diameters; and a cannula shield coupled to the proximal end of the cannula and selectively coupled to the proximal end of the catheter adapter, the proximal end of the catheter adapter having an inner diameter that is greater than the second outer diameter of the cannula such that the cannula and cannula shield are capable of being entirely removed from the catheter and catheter adapter, respectively, and disposed following catheterization.