An introducer needle may include a proximal end, a distal tip, and a needle lumen extending therebetween. The introducer needle may include a wall defining the needle lumen, a first notch formed through the wall, and a second notch formed through the wall. A catheter system may include a catheter adapter, a catheter extending distally from the distal end of the catheter adapter, a flash chamber coupled to the introducer needle, and the introducer needle, which may extend through the catheter. The first and second notches and the flash chamber may facilitate pressure-driven blood flow into the catheter for improved flashback and detection of transfixation when the catheter is primed prior to insertion into vasculature of a patient or otherwise.