Question: My partner told me recently that some time before we met, she had a one night with a man, after which she found herself wanting to pee more often and more frequently. Could she have been infected with some STI by that man? If so, should we both go for a medical check?
Answer: Many STDs or STIs do not present with visible symptoms when a woman becomes infected. The only way to know for sure is for both of you to be tested.
It is possible her sexual experience resulted in a Urinary Tract Infection (UTI) or at least irritation of the urethra. It may have cleared up on its own without requiring medical treatment.
I can only recommend that you see a doctor to find the answer to this question.
Please visit the following website for information on STIs: