Sexually transmitted diseases usually present with pain, irregular bleeding, a raised temperature and/or discharge. If you have some of these symptoms tell your doctor who may arrange some extra investigations. Remember some sexually transmitted diseases have no symptoms at all (e.g. HIV). If you think you are at increased risk of acquiring a sexually transmitted infection you should tell your doctor and be checked on a regular basis.
Some sexually transmitted diseases cause very few symptoms but can cause damage in the pelvis, e.g. Chlamydia, so every precaution should be taken when having sex and if you are in any doubt attend your doctor or Sexual Health Clinic for further investigations and treatment.