Medical Encyclopedia


Medical Encyclopedia

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Contents of this page:


Tuberculosis in the kidney
Tuberculosis in the kidney
Anatomical landmarks, back view
Anatomical landmarks, back view
Anatomical landmarks, side view
Anatomical landmarks, side view
Kidney anatomy
Kidney anatomy
Kidney - blood and urine flow
Kidney - blood and urine flow

Alternative Names    Return to top

Urinary tract infection - complicated; Infection - kidney; Complicated urinary tract infection; Kidney infection

Definition    Return to top

Pyelonephritis is an infection of the kidney and the ureters, the ducts that carry urine away from the kidney.

Causes    Return to top

Pyelonephritis most often occurs as a result of urinary tract infection, particularly when there is occasional or persistent backflow of urine from the bladder into the ureters or an area called the kidney pelvis. See: Vesicoureteric reflux

Pyelonephritis can be sudden (acute) or long-term (chronic).

Pyelonephritis occurs much less often than a bladder infection, although a history of such an infection increases your risk. You're also at increased risk for a kidney infection if you have any of the following conditions:

You are also more likely to get a kidney infection if you have a history of chronic or recurrent urinary tract infection, especially if the infection is caused by a particularly aggressive type of bacteria.

Acute pyelonephritis can be severe in the elderly and in people who are immunosuppressed (for example, those with cancer or AIDS).

Symptoms    Return to top

* Mental changes or confusion may be the only signs of a urinary tract infection in the elderly.

Exams and Tests    Return to top

A physical exam may show tenderness when the health care provider presses (palpates) the area of the kidney.

An intravenous pyelogram (IVP) or CT scan of the abdomen may show swollen kidneys. These tests can also help rule out underlying disorders.

Additional tests and procedures that may be done include:

Treatment    Return to top

The goals of treatment are to:

Due to the high death rate in the elderly population and the risk of complications, prompt treatment is recommended. Sudden (acute) symptoms usually go away within 48 to 72 hours after appropriate treatment.

Your doctor will select the appropriate antibiotics after a urine culture identifies the bacteria that is causing the infection. In acute cases, you may receive a 10- to 14-day course of antibiotics.

If you have a severe infection or cannot take antibiotics by mouth, you may be given antibiotics through a vein (intravenously) at first.

Chronic pyelonephritis may require long-term antibiotic therapy. It is very important that you finish all the medicine.

Commonly used antibiotics include the following:

Outlook (Prognosis)    Return to top

With treatment, most kidney infections get better without complications. However, the treatment may need to be aggressive or prolonged.

Pregnant women and persons with diabetes or spinal paralysis should have a urine culture after finishing antibiotic therapy to make sure that the bacteria are no longer present in the urine.

In rare cases, permanent kidney damage can result when:

Acute kidney injury (acute renal failure) may occur if a severe infection leads to significantly low blood pressure (shock). The elderly, infants, and persons with a weakened immune system have an increased risk for developing shock and a severe blood infection called sepsis. Often, such patients will be admitted to the hospital for frequent monitoring and IV antibiotics, IV fluids, and other medications as necessary.

Severe episodes of acute kidney injury may result in permanent kidney damage and lead to chronic kidney disease.

Possible Complications    Return to top

When to Contact a Medical Professional    Return to top

Call your health care provider if you have symptoms of pyelonephritis.

Call your health care provider if you have been diagnosed with this condition and new symptoms develop, especially:

Prevention    Return to top

Prompt and complete treatment of bladder infections may prevent development of many cases of pyelonephritis. Chronic or recurrent urinary tract infection should be treated thoroughly.

You can help preventing kidney infections by taking the following steps:

References    Return to top

Norrby SR. Approach to the patient with urinary tract infection. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 306

Foster RT Sr. Uncomplicated urinary tract infections in women. Obstet Gynecol Clin North Am. 2008 Jun;35(2):235-48, viii.

Pohl A. Modes of administration of antibiotics for symptomatic severe urinary tract infections. Cochrane Database Syst Rev. 2007 Oct 17;(4):CD003237.

Update Date: 9/18/2008

Updated by: Linda Vorvick, MD, Seattle Site Coordinator, Lecturer, Pathophysiology, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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