Thank you for your query. I would like to inform you that a STD can be transmitted through any type of sex. The contact of the penis to anus or penis to vagina or penis to mouth can cause these problems. Whatever the nature of the unprotected intercourse be, if a partner is suffering from any sexually transmitted disease then he or she may spread it to his or her partner. There may be few superficial cuts in the skin which may not be visible to the naked eye and may not be even felt by the concerned person; in this case the infiltration of the infection through these cuts has a very high possibility. The rectum in a human body is prone to having billions of bacteria called coli forms. These bacteria have very high chances to cause diseases. In any kind of unprotected intercourse, a person may acquire these bacteria into his or her body causing the disease. Any person suffering from any std must know the std symptoms so as to be careful. Once the inflammation takes place, the wound is liable to shrink and then the urethra may get narrowed. In this case a person may have problem in peeing. In few cases the person may have severe problem that would require a surgery. Therefore a person needs to be very careful if he has any of these std symptoms after having insecure sex.so if you have any similar symptoms then you should definitely approach a doctor to seek a good treatment and avoid insecure sex in future. Wish you luck for the future, take care.