If the donor tries to alter the patch by applying a substance to the outside of the patch, the film will no longer be shiny, smooth, or transparent. If the donor tries to alter the patch by injecting a caustic substance under the patch’s outer film, several things may happen. The absorbent pad may become discolored and have an odor, the skin under the pad may become irritated and red, and holes from a hypodermic needle may be visible in the film.
If you suspect that a patch has been tampered with or has been compromised, write what you have observed in box #17 on the chain of custody form. This will provide documentation if the patch is not fit for analysis, or gives unexpected results.