Osteomyelitis is a bone infection caused by bacteria. Bacteria often travel throughout the body via the blood stream. An infection in one area of the body can spread by this route to other parts of the body.
So for example, an abscess of the soft tissues can spread to the bone causing osteomyelitis. The abscess may be caused by some other initial infection such as a urinary tract infection.
In the pelvic or abdominal cavities, there is nothing separating the organs and soft tissues from each other. Any kind of infection or inflammation of the gastrointestinal (GI) tract or genitourinary (GU) tract can affect the soft tissues and bone in the area.
Lab tests of blood and urine combined with an MRI usually help narrow down the diagnosis. A history help identify the risk factors and/or cause of the problem. Treatment follows from there.