Avoid having the i-639 medical exam with Dr John Tang by all means. He is quite irresponsible and unprofessional for the below reasons:
1. He didn’t wash his hands after using his bare hands to take over the urine sample.
Then he have an injection for a tuberculin skin test (TB test) and drew blood with unwashed hands.
2. He didn’t do the medical exam procedures according to what USCIS requires and asked patients to sign I-639 before the test result came out, which was clearly stated as unacceptable on the I-639 form under Part 6
3. He charged extra money to reissue the report to correct his own mistakes
Although his service is relatively cheap, it’s not worthwhile to go through the trouble with him, especially he never admitted his mistakes