Symptoms such as fever or chills or nausea suggest the presence of a more serious infection, such as a kidney infection, and should receive immediate medical attention. Pregnant women may not have any symptoms of infection, so their urine should be checked during their regular prenatal doctor visits.
Most urinary tract infections (UTIs) involve only the bladder and urethra (the lower urinary system). Pyelonephritis results when a UTI progresses to involve the upper urinary system (the kidneys and ureters).
The kidneys filter the blood to produce urine. Two tubes called the ureters carry urine from the kidneys down to the bladder. Urine travels from the bladder out of the body through the urethra.
Most cases of pyelonephritis are complications of common bladder infections. Bacteria enter the...