PYELONEPHRITIS : causes, symptoms, diagnosis and treatment

Pyelonephritis is a bacterial infection of the kidney which leads to inflammation of the kidney. It occurs as a complication of Urinary Tract Infection (UTI). UTI happens commonly when bacteria enters through the urethra to the bladder, which then spreads from the bladder to the kidneys and their collecting systems.

Pyelonephritis presents itself as either acute or chronic. Chronic pyelonephritis occurs due to continuous infections of the kidney. Chronic pyelonephritis is more common in children with urinary obstructions.

Acute pyelonephritis results from sudden and severe bacterial infection of the kidney. Acute pyelonephritis can be divided into uncomplicated and complicated acute pyelonephritis.

Uncomplicated acute pyelonephritis is common to patients who do not have any abnormalities in their anatomy or functionality of their urinary tract.

In complicated acute pyelonephritis however, there is an accompanying condition. These abnormalities in anatomy or functionality of the body increases the chances of the infection getting severe. Example of such predisposing conditions include:

A Brief Look At Your Urinary System

The urinary tract is directly affected by pyelonephritis as it is a route where the bacteria travels through. Your urinary system filters the blood and removes waste products in the form of urine from the body. This urine is drained by the urinary tract which has 4 main parts:

  1. Kidneys: are a pair of bean shaped organs which produces urine as an excretory product. The urine, when produced, leaves the kidneys through the ureters.
  2. The Ureters: are a pair of thick muscular tube, that begins by leaving each kidney at its hilum. They descend downwards carrying urine from the kidney to the bladder where the tube ends into.
  3. The Bladder: is a temporary house for urine. When it gets filled, we get the sensation to urinate called micturition reflex. Urine passes from the bladder to the urethra.
  4. The urethra: is the final passage for urine before it leaves the body during urination.

What Causes Pyelonephritis?

Escherichia coli, is a common bacterium that causes kidney infection. Bacteria travelling through the urinary tract to infect the kidney is the main cause of pyelonephritis.

Urine produced by the body is normally sterile, but the presence of bacteria in the urine is considered abnormal and this can cause pyelonephritis.

So then, how does this bacterium enter the urine and in general how does it even get into the body?

  1. Ascending tract infection: This is the common cause of acute pyelonephritis. In this case, bacteria from outside, either travelling from the vagina or the rectum, enters the body through the urethra. The bacteria may then ascend through the urinary tract to the kidneys infecting it. Inserting non sterile catheters to remove urine may predispose people to pyelonephritis.
  2. Urinary tract obstruction: This is the predominant cause of chronic pyelonephritis. It is due to an enlarged prostate which can block the urethra, hence preventing normal urine flow. Obstruction could also be from kidney stones.
  3. Hematogenous spread: This is the spread of infection to the kidney by bacteria such as staphylococcus and Escherichia coli through the blood. It is an uncommon mode of transfer.
  4. Vesico-ureteral reflux: Normally, urine is supposed to flow from the ureter to the bladder. But in vesico-ureteral reflux, urine from the bladder flows back the opposite way, carrying bacteria along with it into the ureter. This could occur when the valve preventing urine from going back up from the bladder to the ureter is faulty. It can also occur in neurogenic bladder, where patients lack control of their bladder due to damage to nerves, leaving the bladder full. When this happens, the patient is unable to empty his bladder, which can enable bacteria in the standing urine move upward the urinary tract.

Who Is Most At Risk?

Pyelonephritis can affect anybody. It affects males, females, children, the elderly and even pregnant women. This notwithstanding, it is seen a lot more in females than males. It is also more common in the extremes of ages with 2 peaks: one at 0-4 years and the other in patients at 65 years and more.

Some risk factors are usually associated with problems that affects urine flow. Risk factors of getting diagnosed with pyelonephritis in women are;

Risk factors in males include:

However, the general risk factors for pyelonephritis in both genders are:

  • Urinary tract instrumentation such as insertion of non-sterile catheters into the urinary tract.
  • Diabetes mellitus.
  • Vesico-ureteral reflux.
  • Enlarged prostate. This can block the urethra causing obstruction in the urinary tract due to its location close to the urethra.
  • Urinary tract surgery.
  • Chronic Kidney stones or other kidney and bladder conditions.
  • Compromised immune system.
  • Neurogenic bladder (which is a condition where patients lack control of there bladder).
  • Certain medications.

Infants and the elderly are also at risk due to abnormalities in their urinary tract anatomy and changes in hormones. Recurrent acute pyelonephritis is a risk factor to getting chronic pyelonephritis.

How Do I Know I Have Pyelonephritis?

The most common signs and symptoms of pyelonephritis are a high fever, often over 103˚F (39˚C), and a flank pain. But other signs and symptoms such as those listed below could also help your doctor diagnose whether you have the condition:

  • Nausea.
  • Vomiting.
  • Abdominal pain.
  • Shivering.
  • Painful urination.
  • Pus or blood in the urine.
  • Frequent urination.
  • Urge to urinate.
  • Malaise and weakness.

In elderly patients and those with a weak immune system, symptoms of pyelonephritis can appear as:

Pyelonephritis can be fatal if not treated properly. So it is very necessary to seek medical care quickly if you think you may be down with any of these symptoms.

Pyelonephritis in Pregnancy

There are so many changes that occur in the body during pregnancy. Pregnancy increases the risk for urinary tract infections. Pregnant women who have urinary tract infections during their pregnancy can develop pyelonephritis.

Pyelonephritis in pregnant women can threaten the lives of both mother and child. So pregnant women with symptoms should consult the obstetrics and gynecology department. This will help ensure that both mother and child remain healthy throughout the pregnancy period.

Usually, your doctor or midwife would ask you questions during your antenatal visits and run some urine tests. Ensure you don’t miss your routine visits and tell your healthcare provider any complaints you may be feeling in your body. They will carry out a proper check up and treat the problem before it causes any complications.    

Hospital Diagnosis

Diagnosing pyelonephritis is crucial and important, as many other conditions present similar symptoms. Try to remember your symptoms and probably write them down when going to see your doctor.

The following will be done when you get to the hospital:

  • A medical history: where your doctor asks questions about your health and inquire about your medical history.
  • Physical exam: where your doctor presses your abdomen trying to locate pain to help diagnose the condition.
  • Urinalysis: where they take your urine sample for a test. It can help detect urinary tract infections which can lead to pyelonephritis.
  • Urine culture: is a test which can detect bacteria in the urine and is capable of identifying what bacteria is causing the infection.
  • Blood culture: This test can determine if the bacteria is in the blood.
  • Computed tomography (CT) scan: shows computer generated images of the insides of the abdomen can detect blockage in the urinary tract which can lead to pyelonephritis.  
  • Digital rectal examination (DRE): is a physical examination of the rectum. With this examination, the doctor is able to identify an enlarged prostate which can block the urethra leading to pyelonephritis. 

The doctors also look for problems that can cause kidney infection, such as kidney stones or congenital abnormalities. These can be treated to prevent further infections that could lead to a chronic pyelonephritis.

Treatment of Pyelonephritis


Early and proper treatment of this infection is important to prevent other complications. Pyelonephritis hampers the kidney functions, and recurrent infections on the kidney can lead to a chronic condition.

The common complications include:

  • kidney scarring especially in children.
  • Kidney abscess.
  • Urosepsis, (when a urinary tract infection causes sepsis).
  • Renal vein thrombosis.
  • Emphysematous pyelonephritis, which is a severe form of pyelonephritis in diabetic patients.
  • Acute renal failure.

The good news is that pyelonephritis is very treatable. Pyelonephritis can be managed as either outpatients or inpatients. Female patients who present with uncomplicated acute pyelonephritis can be treated as outpatients.

Inpatients treatment is usually for those who are:

  • very young,
  • elderly and immuno-compromised,
  • patients with diabetes,
  • kidney transplants,
  • patients with urinary tract abnormalities, and
  • pregnant patients.

Doctors commonly use antibiotics to treat Pyelonephritis. Hospital admission usually is in complicated cases of acute pyelonephritis. Such cases may require intravenous (IV) antibiotic treatment until clinical improvements are noticed.

Surgery (nephrectomy) may be required to remove obstructions and to correct any kidney defect. Doctors do this in cases of severe infection.

Prevention of Pyelonephritis

Since pyelonephritis is due to bacterial infection, maintaining a good hygiene is very important to reduce the chances of infection. As part of the prevention tips of pyelonephritis:

  1. Always urinate after sexual intercourse to flush the bacteria out of the urethra.
  2. Females should wipe from front to back after urinating and defecating to prevent introduction of bacteria into the urethra.
  3. Patients should finish entire dose of antibiotics as prescribed by the doctor to prevent chronic pyelonephritis.
  4. Drink plenty of water to increase urination so as to remove bacteria from the urethra.
  5. Preventive antibiotics therapy can sometimes be helpful in women who have recurrent urinary tract infections.
  6. For Individuals with indwelling bladder catheters, it is important that the catheter is changed routinely and cleaned under the guidance of a medic before introducing into the urethra.
  7. Follow tips to prevent and treat kidney stones. Patients with kidney stones maybe susceptible to infection as these stones may serve as a means to spread the infection to other parts of the urinary tract.

Always treat your body as a jewel and protect it from conditions which can be easily prevented. You should always visit your doctor when you have any of these symptoms rather than self-medicating.


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