Answer: A buccal swab procedure should not cause bleeding because the Epithelial tissues do not have a blood supply, there would be no blood at all.
This type of swab is commonly used to test for DNA testing. The test is used by taking a swab and rubbing it around the inside of the cheek for an estimated 30 to 60 seconds and no longer. The entire swab must be sure to make contact with the inside of the cheek. It must never touch anything else such as the gums, lips, or teeth.
The person doing the test must be using sterile gloves and a sterile swab. if it is not sterile, the results may be inaccurate.