Causes of pyuria include urinary tract infections, says About.com. It can also be caused by kidney infection, says Mayo Clinic. Sterile pyuria is often caused by sexually transmitted diseases such as gonorrhea, chlamydia, genital herpes and HIV, claims the New England Journal of Medicine.
Urinary tract infections are fairly common among women, says About.com. They are caused when bacteria from the bowels enters the urethra and sets up an infection. The risks of a UTI increase when the woman does not practice good hygiene, if she has multiple sexual partners, or has sexual intercourse more vigorously or frequently than usual. A course of antibiotics usually clears up a urinary tract infection.
Sterile pyuria is a finding of pus in the urine when no bacteria is present, says the New England Journal of Medicine. Besides STDs, genitourinary tuberculosis is another cause of pyuria as well as blood in the urine. If not treated, this condition can damage the patient's kidneys, ureters and sexual organs. Fungal and parasitic infections as well as inflammatory conditions and autoimmune diseases such as Kawasaki's disease also have sterile pyuria as a sign. Sterile pyuria is not restricted to infections in the urinary tract but can be seen in patients with pneumonia, bacterial septicemia, cystitis caused by radiation and bladder stones.