This invention concerns urinary catheterizing and identifies a cavitation occurring at catheter removal as the source of a damaging problem, and shows that a vent to atmosphere of the catheter tip prior to the catheter and vent removal prevents this problem. This invention disclosure shows the vent and method to prevent this problem.The prior art for self-catheterizing specifies six catheterizes and catheter removals per day. Each catheter removal causes a small amount of damage, damage is cumulative and enlarges at subsequent catheterizes. After many catheterizes, the enlarged damage at catheter removal causes a serious bleeding problem.This invention has two cooperative parts related in time as early and later. The early part inserts a lubricated catheter to urethra and bladder to remove urine, and the later part inserts a vent to a catheter urine discharge lumen and catheter tip to prevent this problem at the catheter and vent removal.
