While not all STDs exhibit symptoms, they can have dangerous sequelae. A sequela is a medical condition which results from a previous disease, and is otherwise known as a complication of an untreated disease. Certain STDs, if not treated, can cause pelvic inflammatory disease (PID) in women, which can lead to health problems like ectopic pregnancy or infertility. In men, untreated STDs—even in asymptomatic cases—can cause a painful condition in the vas deferens, the tubes attached to the testicles. In rare cases, this can cause sterility, or the inability to have children. All confirmed cases of STDs should be treated. In most cases, the treatment is straightforward and risk-free, which cannot be said for the complications of untreated STDs. It is in your best interest—and the best interest of your partner(s)—to receive treatment for any and all STDs.