Pyelonephritis

What Is It?

Pyelonephritis is a kidney infection usually caused by bacteria that have traveled to the kidney from an infection in the bladder.

Women have more bladder infections (also called urinary tract infections) than men because the distance to the bladder from skin, where bacteria normally live, is quite short and direct. Usually, however, the infection remains in the bladder.

A woman is more likely to develop pyelonephritis when she is pregnant. Pyelonephritis and other forms of urinary tract infection increase the risk of premature delivery.

A man is more likely to develop the problem if his prostate is enlarged, a common condition after age 50. Both men and women are more likely to develop pyelonephritis if they have any of the following conditions:

• An untreated urinary tract infection
• Diabetes
• Nerve problems that affect the bladder
• Kidney stones
• A bladder tumor
• Abnormal backflow of urine from the bladder to the kidneys, called vesicoureteral reflux
• An obstruction related to an abnormal development of the urinary tract

Tests or procedures that involve the insertion of an instrument into the bladder also increase the risk of urinary tract infections and pyelonephritis.

Children sometimes develop pyelonephritis because of an abnormality in the bladder that allows urine there to flow backwards (reflux) into the ureter, the connection between the kidney and bladder. This can lead to scarring of the kidney.

Rarely, pyelonephritis is so severe that it is life threatening, especially in older people or in those with an impaired immune system.

Symptoms

Pyelonephritis usually begins with a sudden, intense pain in one flank, the area just beneath the lower ribs in the back. This pain can travel around the side toward the lower abdomen, or down to the groin. There also can be a high fever, shaking chills, and nausea and vomiting. The urine may be cloudy, tinged with blood, or unusually "strong" or foul-smelling. Additional bladder-related symptoms can include the need to urinate more often than normal, and pain or discomfort during urination.

Diagnosis

If your doctor is concerned that you have a kidney infection, he or she will ask you about other medical problems, any past infections and your recent symptoms. He or she also will check your vital signs (temperature, heart rate, blood pressure), and will press on your abdomen and flanks to see if there is tenderness near the kidney. In women, the symptoms of pyelonephritis may be similar to those of certain sexually transmitted diseases, so your doctor may recommend that you have a pelvic examination.