Questions about oral sex are very frequent on the forum. I'm going to take this opportunity for an expanded reply to which I can refer other questioners in the future.

The main thing to understand is that fellatio (oral-penile sex) is low risk for all STDs and zero risk for some. It's not completely free of risk, but far less likely to transmit STDs than unprotected vaginal or anal intercourse. In general, what risk exists is mostly for the oral partner, i.e. transmission from penis to the mouth or throat is more frequent than in the other direction.

Some STDs are not carried in the mouth or oral fluids, or only rarely, therefore cannot be transmitted to a partner's penis. These include HIV, chlamydia, herpes due to HSV2, viral hepatitis, and HPV. (In 40+ years in the STD business, I've rarely if ever seen any patients with these STDs acquired by oral sex.)  The main STDs from such exposure are gonorrhea; nongonococcal urethritis (NGU), which may often be caused by normal bacteria that irritate the urethra; and herpes due to HSV1, the cause of most oral herpes. Syphilis is possible, but very uncommon, especially in heterosexuals; in North America and western Europe, the large majority of syphilis these days is in men who have sex with men. While your risk of syphilis might be slightly higher given its higher frequency in Russia and eastern Europe, it's still a very uncommon outcome.

All these STDs usually would cause symptoms at various intervals. If no urethral discharge and painful urination by 4-5 days, you can safely assume you didn't catch gonorrhea. Same for NGU and herpes if no discharge or penile blisters or sores within 10 days. The chancre (open sore) of initial syphilis takes longer, typical onset 2-3 weeks but sometimes as long as 4 weeks after exposure.

Because the overall risk is low, in general STD experts do not recommend testing for STDs after any single episode of oral sex unless there are symptoms, or if the oral partner is known to be infected. I will also point out that STD risks generally are low in "escorts", i.e. expensive female sex workers by appointment. Many such women know how to protect themsevles, choose clients whose own behaviors usually are low risk (like you!), and are tested frequently. That's not a guarantee, but the risk probably is a lot lower than with street or brothel workers, bar pickups, etc.

Nevertheless, some men in your situation will want to be tested, if only for the reassurance value of the negative results. If so, then after 4-5 days you can have a valid urine test for gonorrhea and chlamydia. (Chlamydia testing isn't really necessary, but is almost always done automatically along with gonorrhea testing.) And after 6 weeks, a blood test for syphilis. HIV testing can also be done, but here too there is virtually no risk. There is no test for nonchlamydial NGU, just exam by a professional -- but really no need if no penile discharge or painful urination after 10-14 days. And testing for herpes is not very useful in this situation unless there are symptoms.

I hope these extended comments have been helpful, but let me know if anything isn't clear. Best wishes and stay safe--

HHH, MD