Valve retainer ring and related systems and methods

A method of flushing a catheter assembly, comprising:

• coupling an infusion device to a side port of a catheter adapter of the catheter assembly, wherein the catheter assembly comprises:
• a catheter adapter, comprising a distal end, a proximal end, an inner surface forming a lumen, the lumen extending through the distal end and the proximal end, and a side port disposed between the distal end and the proximal end;
• an annular valve disposed within the lumen and aligned with the side port, wherein the annular valve seals a fluid pathway from the side port to the lumen;
• a retainer ring disposed proximal and proximate the annular valve within the lumen;
• and
• a catheter extending distally from the distal end of the catheter adapter;
• activating the infusion device, wherein in response to activating the infusion device, a proximal end of the annular valve is opened to allow fluid to flow proximally through the retainer ring, wherein in response to activating the infusion device, a proximal end of the annular valve is forced against the retainer ring and the retainer ring remains in place.