A chemical formula that indicates the simplest numerical ratio of the elements within a molecule, without demonstrating the molecule's chemical bonds or structure. For example, the empirical formula for water is H2O. Synonym: molecular formula.
Pelvic inflammatory disease (PID) is an infection caused by bacteria. When bacteria from the vagina or cervix travel to your womb, fallopian tubes, or ovaries they can cause an infection. Most of the time, PID is caused by bacteria from chlamydia and gonorrhea. These are sexually transmitted infections (STIs). Having unprotected sex with someone who has an STI can cause PID.
Your risk for PID is higher if you: 1  Have had an STI. 2  Have had PID before. 3  Are younger than 25 and have sex. PID is most common in women 15 to 24 years old. 4  Have more than one sex partner or have a partner who has multiple sexual partners. 5  Douche. Douching can push bacteria into the reproductive organs and cause PID.