What is meant by the term Pyelonephritis ?
The term Pyelonephritis refers to an infection in the kidney. This
infection is due to infectious organisms, usually bacteria, fungi and
occasionally viruses. These organisms can be grown from the urine.
There are two forms of pyelonephritis: Acute Pyelonephritis refers
to an acute infection in kidneys which have no scars or any underlying abnormality which predisposes to urine infection. Acute Pyelonephritis does not give rise to scarred kidneys.
Chronic Pyelonephritis refers to an infection in kidneys which are
coarsely scarred. The cause for such scarring is due to a combined
effect of infection and the retrograde flow of urine up the kidney
from the urinary bladder past damaged valves at the junction of the
bladder and the ureter. This condition of retrograde flow of urine
into the kidney from the bladder is known as vesico-ureteric reflux.
Vesico, derived from the word Vesicle, refers to the bladder and
reflux, the retrograde flow.
What is vesico-ureteric reflux?
Urine normally flows from the kidneys along the ureters and into
the bladder. When the bladder contracts during the act of passing
urine, valves which are present at the junction of the bladder and
ureters also contract to prevent the urine from flowing backwards up
to the ureters. At the same time the valve at the opening of the
bladder called the urethral valve relaxes and urine passes out from the
bladder to the urethra and the bladder empties itself. In some people,
usually children, there is a congenital defect in the valves at the
junction of the bladder and ureters so that during the act of passing
urine, urine flows backwards into the kidneys. This condition predisposes to urine infection and it is a combined effect of this vesico-ureteric reflux and the infected urine which causes scarring of the
kidneys. If the scars progress with time, the patient will develop
This reflux of urine will not show up on an intravenous pyelogram
( IVP X-ray ) but the presence of a particular pattern of scarring is a
clue to the diagnosis. In order to demonstrate the presence of vesico-
ureteric reflux, a cystogram or X-ray of the bladder is performed.
This involves taking X-ray pictures during the act of passing urine to
see if any urine goes backwards into the kidneys.
What is meant by Cystitis?
Cystitis refers to an infection of the urinary bladder. One of the
clues to cystitis is the site of the pain or discomfort at the area just
above the pubic bone where the bladder is situated. This is usually
associated with passing of urine many times a day. The passage of
urine may cause pain at the urethra and there may be blood in the
How does urine infection occur?
There are two routes of urine infection. Bacteria can enter the
bloodstream and from there go to the kidneys to cause an infection in
The other more common route is by what is known as ascending
infection. Here the bacteria comes from outside and enters the
urethra and gets into the bladder. From the bladder the bacteria
ascend the ureters and get into the kidneys to cause infection. If the
infection localizes in the bladder then the patient has only a cystitis
and if in the kidneys she has pyelonephritis.