How to select the injection point for blunt needle filling injection?

Because the blunt needle has a round blunt end, this particular design is designed so that the blunt needle does not directly Pierce the tissue, so an opening of the skin needs to be created using a "starting" needle or an intervention needle. Of course, the larger the opening, the easier it will be to get a blunt needle through, but the resulting hematoma will be larger, causing more pain, bruising and swelling. On the other hand, smaller openings make it more difficult for blunt needles to penetrate and also cause significant pain in the case of repeated piercings and inability to access through the opening. Therefore, the optimal choice should be based on the proficiency of different puncture operators, using the smallest size needle as the starting needle that will not cause repeated puncture.