Why do I get a UTI after sex?

Bacteria milked up. Bacteria from outside and around the urethral opening, which is only 1-2 millimeters away fro the vaginal opening, get pushed up the urethra by the pumping action of penis in the vagina, which lies directly under the urethra. Thus bacteria are "massaged", pushed or milked up into the bladder where they multiply and cause a uti. Hence advice to empty bladder after sex.

Related Questions

Why do I get uti's after sex?

Flush them out! During sex, there are several exchanges. Skin cells, fluids and bacteria are the most common exchanges. Women are most affected during these exchanges due to our short urethras. The debris can get to the opening of the urethra and travel a short distance to the bladder and wreak havoc! urinate as soon as you can after sex to "flush out" the possible debris. Drink plenty of water to help you out. Read more...
UTI. For females, utis are prone due to their anatomy following intercourse as it introduces bacteria to the urethra. Read more...

Why do I get a UTI every time after sex? How do I prevent this?

Honeymoon cystitis. This is a phenomenon observed in newly weds, who have sex for the first time and lots of it. The female urine pipe draining the urine from the bladder is comparably short, and accommodates bacteria to be pushed into the bladder during intercourse. If drinking plenty of fluids does not help, a short course (1- 3 days) of antibiotics may remedy the situation. Read more...