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.
PID occurs when the disease-causing organisms travel from the cervix to the upper genital tract. Untreated gonorrhea and chlamydia cause about 90% of all cases of PID. Other causes include abortion, childbirth, and pelvic procedures.