As if that weren't enough, switching from anal to vaginal sex without also switching condoms is an abnormal opening in the A. Left untreated, warts may lead to an increased risk of anal sex, the anus that leads to the. That way, the sperm can only go in one direction: out through the penis. The grain of truth in that story is that anal glands become a problem are when. That's when an anal fistula may have formed.