Most urinary tract infections (UTIs) involve only
the bladder and urethra (the lower urinary
system). Pyelonephritis results when a UTI
progresses to involve the upper urinary system
(the kidneys and ureters).
The kidneys filter the blood to produce urine. Two
tubes called the ureters carry urine from the
kidneys down to the bladder. Urine travels from
the bladder out of the body through the urethra.
Most cases of pyelonephritis are complications of
common bladder infections. Bacteria enter the
body from the skin around the urethra. They then
travel up the urethra to the bladder.
Sometimes, bacteria escape the bladder and
urethra, traveling up the ureters to one or both
Pyelonephritis is a potentially serious kidney
infection that can spread to the blood, causing
severe illness. Fortunately, pyelonephritis is
almost always curable with antibiotics.
The urethra is much shorter in women than in
men, which is one reason why women are more
vulnerable to UTIs and pyelonephritis.
Symptoms of Pyelonephritis
At least half of women have experienced the
discomfort with urination caused by a urinary tract
infection: painful, urgent, or frequent urination.
Pyelonephritis may start with similar symptoms.
However, once the infection has spread to the
kidney, signs of more severe illness usually result.
Back pain or flank pain
Fever (usually present) or chills
Feeling sick (malaise)
Nausea and vomiting
Confusion (especially in the elderly)
Pyelonephritis may cause noticeable changes in
the urine, such as:
Blood in the urine (hematuria)
Cloudy or foul-smelling urine
Pain when urinating
Increased frequency or urgency of urination
Causes of Pyelonephritis
Most often, the bacteria that cause pyelonephritis
are the same as those that cause ordinary urinary
tract infections. Bacteria found in stool (such as E.
coli or klebsiella) are most common. Uncommonly,
bacteria from the skin or the environment cause
Conditions that create reduced urine flow make
pyelonephritis more likely. When urine flow slows
or stops, bacteria can more easily travel up the
ureters. Some causes of urine obstruction include:
Benign prostatic hypertrophy (BPH)
Abdominal or pelvic masses (as from cancer)
Stones in the bladder, ureters, or kidneys
Kidney stones contribute to pyelonephritis by
providing a place for bacteria to grow while
evading the body's defenses.
People with diabetes or conditions that impair the
immune system are more likely to get
How Pyelonephritis Is Diagnosed
Doctors may rely on various tests to diagnose
History. Telling the story of your illness and
specific symptoms helps a doctor make the
diagnosis of pyelonephritis.
Physical examination. A doctor notes a person's
general appearance, vital signs, and presses over
the kidneys to check for tenderness.
Urinalysis. In pyelonephritis, microscopic analysis
of the urine virtually always shows signs of
infection. This can include an excess of white
blood cells and bacteria.
Urine culture. Within days, bacteria in urine may
grow on a culture dish, allowing the best antibiotic
to be chosen.
Blood cultures. If pyelonephritis has spread to the
blood, blood cultures can detect this and guide
Computed tomography (CT scan). A scanner takes
a rapid series of X-rays, and a computer creates
detailed images of the abdomen and kidneys. A CT
scan is not necessary to diagnose pyelonephritis,
but sometimes helps.
Kidney ultrasound. A probe directs high-frequency
sound waves through the skin, creating images of
the kidneys and ureters. Ultrasound can help
identify abscesses, stones, and blockages.
In addition to diagnosing pyelonephritis itself,
doctors look for any conditions that make
pyelonephritis more likely. For example, kidney
stones or birth defects of the urinary tract can
increase the chance of an infection. Both are
potentially correctable, which will reduce the
chances of future kidney infections.
Treatment of Pyelonephritis
Pyelonephritis is a serious infection that always
requires treatment with antibiotics. Home remedies
alone aren't effective or recommended for
For most cases of pyelonephritis, hospitalization
isn't required. Home treatment is appropriate if a
person is able to get around and can consistently
take oral antibiotics. For example, they must not be
confined to bed or regularly vomiting.
Hospitalization is required to treat more severe
pyelonephritis, however. Delivering antibiotics
intravenously in the hospital ensures that the
medicine is reaching the kidneys.
Antibiotics are generally prescribed for a total of at
least seven days. Part of this course of treatment
may be given in the hospital intravenously; the
remainder of the treatment may be taken at home
in the form of pills.
In rare cases, pyelonephritis may progress to form
a pocket of infection (abscess). Abscesses are
difficult or impossible to cure with antibiotics alone
and must be drained. Most often, this is done with
a tube inserted through the skin on the back into
the kidney abscess (a procedure called a
Acute and Chronic Pyelonephritis
Most cases of pyelonephritis are acute, meaning
sudden and self-limited. After cure with antibiotics,
there is rarely any lasting damage to the kidneys.
Most people do not develop pyelonephritis again.
Chronic (long-lasting) pyelonephritis is a rare
condition, usually caused by birth defects in the
kidney. Repeated UTIs (usually in children) result
in progressive damage and scarring in the kidney.
This can eventually cause kidney failure. Usually,
chronic pyelonephritis is discovered in childhood.