Definition & Overview

Pyelonephritis is a type of urinary tract infection (UTI) that affects the kidneys. The urinary tract is composed of the bladder, urethra, kidneys, and ureters. Most urinary tract infections begin at the urethra, the final passageway of urine as it is excreted from the body. If untreated promptly, the infection proceeds to the bladder where it is referred to as cystitis, a common type of UTI.

If the infection progresses, it will affect the ureters and the kidneys, which play an important role in the renal system. They filter waste products from around 200 quarts of blood on a daily basis and the waste products are removed from body through the bladder as urine.

Although pyelonephritis is less common than cystitis, it is a very serious condition. If it is not treated in time, it can lead to kidney damage, which will eventually result in complete kidney failure. Once this happens, the patient will require dialysis and later on, a kidney transplant.

Pyelonephritis can also lead to a condition called sepsis. Although this rarely occurs, it is very serious as the infection is no longer contained in a single area but travels to the rest of the body through the bloodstream.

Cause of Condition

A wide variety of bacteria and viruses can cause pyelonephritis, but the most common is Escherichia coli. This type of bacteria typically originates from the bladder and move up to the kidneys through the bloodstream.

The bacteria can affect anybody of any age, but it is more common in those who already have a bladder infection or in people with structural or anatomical abnormalities in the urinary tract. These types of structural problems prevent urine from flowing in a normal manner.

A normal flow of urine can be disturbed by kidney stones, an enlarged prostate gland, or a defective valve mechanism that prevents urine from flowing back into the kidneys, a condition called vesicoureteral reflux (VUR).

Pregnant women with diabetes and a weakened immune system are also at risk of developing pyelonephritis.

Key Symptoms

  • Chills
  • Fever
  • Vomiting and nausea
  • Painful and frequent urination
  • Pain in the backside and groin

Who to See & Types of Treatment Available

Patients who experience the symptoms mention above can consult a general practitioner or their primary care physician. The condition is diagnosed through urinalysis, ultrasound, CT-scan, and a voiding cystourethrogram, which is a type of x-ray.

Antibiotics are the first line of treatment for this condition and are usually very effective. The symptoms should subside within a couple of days.

Meanwhile, severe cases require admission to the hospital, in which case, the antibiotics will be administered intravenously. The length of the hospital stay will be determined by the severity of the condition and the patient's response to the treatment.

Since infections can be caused by structural abnormalities, treating them with antibiotics will only result in a temporary solution. The infection will likely recur as long as the structural problem is not fixed. Surgery will be required to repair the problem such as kidney stones to minimize the risk of recurrences.


  • National Institute of Diabetes and Digestive and Kidney Diseases
  • Urology Care Foundation of the American Urology Association
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