Curious

Dr. what is the chance of contracting a std if you only rub your penis on the outside of a womans anus with no penetration and is frequent urination a sign of a std a lot of sights say so.

[H. Hunter Handsfield, M.D.]

Genital apposition--i.e. genital contact (or anal contact) without penetration--is very low risk.  There is some chance of transmitting herpes or HPV, if either person is actively infected, and a theoretical chance of syphilis, but syphilis is rare to nonexistant in most population groups in the US.  There is no chance of gonorrhea, chlamydia, or NGU, which are the only STDs likely to cause urinary symptoms.

Frequent urination, without pain or discharge, is not an STD symptom.  When frequent urination is present with those other symptoms, it is an urgent need to pee with very small volumes, usually with pain or burning when actually voiding.  Simply going to the bathroom frequently is not the same thing.  But as you probably learned, lots of website and other education materials simply state "frequent urination" without these qualifications.

Bottom line (no pun intended), I doubt you have an STD.  But of course see a health care provider if your frequent urination bothers you, or if you develop other symptoms as well.

Good luck--  HHH, MD