The doctor actually drew a drawing to show me why sex causes a UTI. I'll try to explain it here without it being too graphic.....

She drew a view of how she would see the female area if she were doing an exam. If you look it it that way, the clitoris is on top, then the urethra (where we urinate from) and then the vaginal hole. She said this: "Its a design flaw really. In order for sex to feel good, the clitoris needs to be stimulated, but its on top of the urethra. So the penis goes in and out of the vaginal hole, which brings all that bacteria up passed the urethra. The urethra is a just a short tube to the bladder where all the warm urine sits, which is the perfect medium for bacteria to grow." I cracked up with her whole design flaw thing. And this is also why if you pee directly after sex, you can prevent UTI's, because you're flushing out the bacteria that was just put there.

That's also why its important to wipe from front to back.

Don't know why I never knew these details until I was 28.....lol. So I'm glad I can share them with you Jess.