Pyelonephritis: A Review of Literature

Submitted by Marina E. Bitanga BSN, RN, CCRN

Tags: diagnosis infection kidney kidney infection literature review Pyelonephritis urinary tract infection UTI

Pyelonephritis:  A Review of Literature

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Pyelonephritis is a serious type of urinary tract infection where one or both kidneys become infected either by bacteria or virus which can cause people to feel very sick and requires treatment. Kidney infection can be life threatening so it is important to seek medical care quickly if someone thinks he/ she has a kidney infection. If not treated properly, a kidney infection can permanently damage your kidneys or the bacteria can spread to your bloodstream. The presentation is either acute or chronic. Acute pyelonephritis is caused by an ascending infection of the urinary tract or from the hematogenous spread of systemic infections. Chronic pyelonephritis is due to chronic recurrent infections secondary to urinary reflux or an obstruction of the genitor-urinary tract.

The key to outcome in patients with acute pyelonephritis is prompt diagnosis and treatment. Delay in treatment can often lead to high morbidity. Delays in proper management can lead to longer hospital admissions, severe pains, and disability. Even after discharge, follow-up is needed to ensure that full recovery has occurred. Pregnant females with acute pyelonephritis are at a very high risk for premature delivery. The mortality rates are higher in the elderly who have other comorbidities.

Urinary tract is made up of your:

  • Kidneys. These clean waste from your blood and make urine.
  • Ureters. These thin tubes, one for each kidney, carry urine to your bladder.
  • Bladder. This stores urine.
  • Urethra. This tube carries urine from your bladder to outside your body.

These bacterial infections occur in about 3 to 7 of every 10,000 people in the United States.


Only few statistics on the incidence of kidney infections. A 2007 study reported that for females, there were 12-13 outpatients cases and 3-4 inpatient cases per 10,000 females. The numbers were lower for males, with 2-3 outpatient cases and 1-2 inpatient cases per 10,000 males. The highest incidence was among young women , and next were infants and the older adults.


  • Intestinal bacteria like E. Coli entering urinary tract through urethra.
  • Block of urine flow causing infection or wrong direction of urine flow, which is normally from the kidneys to the bladder.
    -   Kidney stones
    -   Tumors inside or outside the urinary tract
    -   Structural problems of the urinary tract

What Are The Risks Factors Of Pyelonephritis?

  • Enlarged prostate
  • Fecal incontinence
  • Hospitalization
  • Immobility
  • Having a condition that causes urine to flow the wrong way. In vesicoureteral reflux, small amounts of urine flow from your bladder back up into your ureters and kidneys.
  • Older age
  • Previous bout of pyelonephritis
  • Having a urinary tract blockage. This includes anything that slows the flow of urine or reduces your ability to empty bladder when urinating. This includes kidney stone and something abnormal in your urinary tract’s structure.
  • Recent urinary tract infection
  • Surgery
  • Urinary catheter
  • Weak immune system. Includes medical conditions that impair your immune system, such as diabetes and HIV. Also certain medications, such as drugs taken to prevent rejection of transplanted organs, have similar effect.
  • Pregnant women with urinary tract infection
  • Being a female. The urethra is shorter in women than it is in men, which makes it easier for bacteria to travel from outside the body to the bladder. The nearness of the urethra to the vagina and anus also creates more opportunities for bacteria to enter the bladder.
  • Having damage to nerves around the bladder. Nerve or spinal cord damage can block the sensations of a bladder infection so that you are unaware when it is advancing to a kidney infection.

Signs and Symptoms:

  1. Fever  - occurs when the set point of body top increases beyond the normal range leading to muscle contractions and feeling of coldness.
  2. Flank tenderness – pain when the area on the back overlying the kidney or costovertebral angle is percussed. Flank tenderness is found in patients with perinephric abscess, renal stones, and pyelonephritis.
  3. Nausea and vomiting
    - Nausea is the uncomfortable sensation where it results in an urge to vomit. It can be debilitating as it causes discomfort in the upper abdomen, chest, and throat.
    - Vomiting is the involuntary expulsion of stomach contents through the mouth and nose.
  4. Burning sensation during urination – also called dysuria which is used to describe painful or difficult urination.
  5. Frequent urination – occurs when the affected individual need to urinate more frequently than normal and is associated with urinary urgency.
  6. Tachycardia – increased heart rate is secondary to fever or pain and maybe sign that the infection is progressing.
  7. Malaise – general feeling of discomfort where there is pain or uneasiness.
    - This is usually one of the first indication of disease or infection.
    - Patients often express it as “ feeling that something is not right.”
    - Malaise is due to activation of an immune response and pro-inflammatory cytokines.
  8.  Loss of appetite – triggered by peptidoglycans and lipopolysaccharides from bacterial cell walls, DNA, viral DNA, and viral glycoproteins
  9. Hematuria – maybe caused by bladder cancer, kidney stones, renal cancer, prostate cancer, testicular cancer, urinary tract infection, pyelonephritis, and other causes.
  10. Tachypneic – this symptom progress to sepsis
  11. Sweating
  12. Chills


Acute pyelonephritis results from bacterial invasion of the renal parenchyma. Bacteria usually reach the kidney by ascending from the lower urinary tract. The development of infection is influenced by bacterial and host factors. Bacteria may also reach the kidney via the blood stream. Hematogenous sources of gram-positive organisms, such as Staphylococcus, are intravenous drug abuse and endocarditis.  Hematogenous spread of gram-negative organisms to the kidney is less likely unless there is an underlying problem that exists such as obstruction. Neutrophils infiltrate the tubules of interstitium and cause suppurative inflammation. There are often small renal cortical abscesses and streaks of pus in the renal medulla.


  1. Hydration – drink plenty of fluids every day the amount can change if you have certain medical conditions or live in hot climate.
  2. Urinate completely
  3. Empty your bladder completely
  4. Do not hold urine which can be harmful and can promote growth of bacteria
  5. Urinate after having sex -  this helps to promote any bacteria that may have gotten into the body.
  6. Practice good hygiene – wiping front to back to push bacteria away from the urethra after bowel movement.
  7. Taking showers instead of baths
  8. Avoid alcohol and caffeine
  9. Avoid tight–fitting pants
  10. Avoiding undergarments made from synthetic materials
  11. Bathing the opening of the urethra thoroughly and regularly
  12. Drinking cranberry juice unless you have kidney stones
  13. Seeing your doctor to treat urinary tract infection


  1. Medical history – what are the symptoms and when they began as well as the general health history
  2. Physical Examination
  3. Abdominal inspection to check for pain or any tenderness
  4. Collect blood and urine samples
  5. Urinalysis – to look for any signs of infection
  6. Urine culture – to help the doctor determine the best antibiotic to use.
  7. Blood cultures – to determine if infection spread in the blood
  8. CT Scan
  9. Shows detailed 3D images of the urinary tract and kidney to dectect problem
  10. To see if there is any blockage that needs treatment
  11. Kidney Ultrasound – create images of the kidneys and ureters to show if there are wounds, stones, or other things that block the urinary tract.
  12. Voiding cystourethrogram (VCUG) - an xray image of the bladder and urethra taken while and bladder is full during urination. This can show problems in the urethra and bladder.
  13. Digital rectal examination (DRE) – Men who have kidney infection may have this exam to see if swollen prostate is blocking the neck of the bladder
  14. Dimercaptosuccinic acid (DMSA) scintigraphy
  15. Special cameras and computers create images to see if kidneys are infected, scarred, or damaged.
  16. Uses small amount of radioactive materials to look closely at how well the kidneys work.

Differential Diagnosis

  • Appendicitis
  • Abdominal abscess
  • Nephrolithiasis
  • Cholecystitis
  • Urinary tract obstruction
  • Pelvic inflammatory disease
  • Pancreatitis
  • Ectopic pregnancy


  • Emphysematous pyelonephritis (EPN) – very rare, potentially fatal complication. It is a severe infection in which necrotizing bacteria destroy kidney tissue. Symptoms include fever, nausea,   
  • Kidney abscesses – pus can accumulate in kidney tissues. Symptoms include blood in urine, weight loss, and abdominal pain. Surgery maybe necessary to drain the pus.
  • Acute renal failure – one or both kidneys may stop working and the per person may need dialysis.
  • Renal vein thrombosis – blood clot in one of the major kidney veins may result in lack of blood in the organ. It can cause acute kidney injury or chronic kidney disease.
  • Blood poisoning or sepsis – may result in person’s blood pressure dropping very low affecting blood circulation. Blood can be moving so slow that it begins to clot within the blood vessels.
    - Symptoms of sepsis includes:  edema, difficulty breathing, fatigue, nausea, confusion, seizures, coma.

Treatment And Management

  • Antibiotics orally or intravenously for two or more weeks
  • Repeat urine cultures to make sure infection does not return. Repeat two more weeks of medicine if infection returns.
  • Surgery if a block in the urinary tract or a birth defect is found.
  • Antiemetics if nausea and vomiting is present
  • Antipyretics if patient develops fever
  • Intravenous fluids for hydration
  • Pain medications

Key Points

  • Pyelonephritis can affect all ages more common in women. Risk factors include urinary tract obstruction due to stress, structural anomaly or enlarged prostate.
  • Diagnosis should be made clinically with typical presentation of fever, flank pain, and nausea/ vomiting. Positive urinalysis associated with flank pain necessitates treatment for pyelonephritis.
  • Early recognition and treatment can prevent long term renal damage.
  • If unresponsive to antibiotics, imaging should be performed to rule out pyonephroses and perinephric abscess which requires drainage.


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