Diseases & Conditions



Diseases & Conditions


What is pyelonephritis?

Pyelonephritis is a type of urinary tract infection that begins in the urethra or bladder subsequently affecting one or both kidneys. The kidneys process the blood to remove wastes and extra water in the urine. Urine travels from the kidneys to the bladder where it is excreted via the urethra. Bacteria can infect the kidneys by entering the urethra and travelling via the bladder into the kidneys.

Worldwide prevalence and incidence of acute pyelonephritis are unknown.1 Although pyelonephritis can occur at any age, it is more common in neonates with abnormalities of the renal tract, in girls and in women.2


What causes pyelonephritis?

Pyelonephritis is caused by bacteria or viruses infecting the kidneys. The bacterium Escherichia coli is often the cause of this infection. The bacteria enter through the opening of the urethra moving upwards infecting the bladder than the kidneys. The bacteria could enter to the urinary tract accidently from the anus when wiping after going to the toilet. When the dirty toilet paper touches the genitals, the bacteria can get into the urinary tract and infecting the kidneys later on.3


What are the risk factors for pyelonephritis?

Factors that can increase the risk of developing pyelonephritis include:4

  • Gender: Women are at higher risk of developing pyelonephritis due to their anatomy. Woman has a shorter urethra than a man does and hence bacteria have less distance to travel from outside the body to the bladder. Moreover, the close proximity of the urethra and the rectum makes it easier for bacteria to enter the bladder.
  • Obstruction in the urinary tract: The presence of obstruction of the urinary tract (stone, tumor, bladder neck obstruction, enlarged prostate) increases the risk of developing pyelonephritis.
  • Weakened immune system: People with diabetes or a weakened immune system (HIV-infected patients) are more prone to develop pyelonephritis.
  • Damage to nerves around the bladder: Any damage to nerves around the bladder may block the symptoms of a bladder infection and the patient may not be aware of his progressing disease.
  • Prolonged use of a urinary catheter: After certain surgical procedures, a catheter could be placed in order to drain urine from the bladder increasing the risk of pyelonephritis.
  • Vesicoureteral reflux: This condition causes urine to flow backwards from the bladder to the kidneys and may lead to pyelonephritis.


What are the symptoms of pyelonephritis?

Signs and symptoms of pyelonephritis may include:5

  • Fever
  • Chills
  • Back pain
  • Malaise
  • Nausea
  • Vomiting
  • Blood in the urine
  • Pain when urinating
  • Frequent urination
  • Cloudy and smelly urine


How is pyelonephritis diagnosed?

Tests used to diagnose pyelonephritis depend on the patient’s age and gender and include the following:6

  • Urinalysis: The testing of urine sample can reveal white blood cells and bacteria indicating infection.
  • Urine culture: A urine culture will determine the type of bacteria causing the infection.
  • Ultrasound: An ultrasound creates an image that can show obstructions in the urinary tract.
  • Computerized tomography (CT) scan: CT scans use X-rays to create images that can show obstructions in the urinary tract.
  • Voiding cystourethrogram (VCUG): A VCUG is an X-ray study of the bladder and urethra. It is done while the bladder is emptying. This test can show abnormalities of the inside of the urethra and bladder.
  • Digital rectal examination (DRE): A DRE is a simple procedure doctors use to examine the prostate. This examination can show if an enlarged prostate is causing the obstruction of the neck of the bladder in men with pyelonephritis.
  • Dimercaptosuccinic acid (DMSA) scintigraphy: A DMSA scan uses radioactive chemicals to create special pictures of the kidneys.


How is pyelonephritis treated?

Treatment of pyelonephritis depends on the severity of the infection and includes:7

  • Antibiotics: Pyelonephritis is treated with antibiotics for several weeks.
  • Hospitalization: For severe kidney infection, a hospitalization is required and an intravenously antibiotics is required.
  • Surgery: A urologic abnormality may cause recurrent kidney infections. A surgery to repair the structural abnormality is required to avoid recurrent pyelonephritis.



  1. BMJ Best Practice http://bestpractice.bmj.com/best-practice/monograph/551/basics/epidemiology.html (Accessed January 27, 2016)
  2. Patient http://patient.info/doctor/pyelonephritis (Accessed January 27, 2016)
  3. Urology Care Foundation - Kidney (Renal) Infection – Pyelonephritis http://www.urologyhealth.org/urologic-conditions/kidney-(renal)-infection-pyelonephritis (Accessed January 27, 2016)
  4. Risk factors http://www.mayoclinic.org/diseases-conditions/kidney-infection/basics/risk-factors/con-20032448 (Accessed January 27, 2016)
  5. WebMD http://www.webmd.com/a-to-z-guides/kidney-infections-symptoms-and-treatments#1 (Accessed January 27, 2016)
  6. Pyelonephritis: Kidney Infection http://www.niddk.nih.gov/health-information/health-topics/kidney-disease/pyelonephritis-kidney-infection/Pages/index.aspx (Accessed January 27, 2016)
  7. Treatments and drugs http://www.mayoclinic.org/diseases-conditions/kidney-infection/basics/treatment/con-20032448 (Accessed January 27, 2016)