We do not consider receiving oral sex as a risk for HIV. Therefore, you should not have to repeat the HIV test for the oral sex you got 4 weeks ago.
However, it is possible to get other STIs when you receive oral sex. These include Chlamydia, gonorrhea, HPV, herpes and syphilis.
Your urine tests done at 4 weeks should have been accurate for gonorrhea, because most results are accurate after 7 days. The test for Chlamydia is most likely accurate at 4 weeks, but it can take up to 6 weeks to show up.
The blood test for syphilis, done at 4 weeks, may be a bit early. Most tests will become positive within 6 weeks, but it can take as long as 3 months to show up.
You might find it helpful to look at our “STI at a Glance” chart. It gives information on window periods and you can see when tests will be most accurate.
You may want to repeat some tests, such as Chlamydia and syphilis, 6 weeks to 3 months after the contact you had.
Please leave a comment to let us know if that answers your question or if you need more information.