Pyelonephritis is a severe bacterial infection of one or both of the renal pelvises. This is the space in the kidney where the urine is collected before it flows into the ureters. Because of the ascending urinary tract infection, the wall of the renal pelvis gets inflamed. Pyelonephritis is a very painful condition.


An inflammation of the renal pelvis is in most cases caused by Escherichia coli, a bacterium which belongs in the large intestine. These bacteria enter the bladder via the urethra. From the bladder they end up, via the ureter, in the renal pelvis. After infection, it takes one to twelve days before the first symptoms occur. Sometimes, pyelonephritis is also caused by an improperly treated bladder infection or a kidney stone. In some cases, pyelonephritis is caused by tubercolosis or fungal infection.
The risk of pyelonephritis is increased in people with a blockage of the ureters, in case of diabetes mellitus, a poor immune system (making the body combat infections less properly) and in pregnant women.


Pyelonephritis is in symptoms similar to a bladder infection, but is more serious. In both cases, the urine is turbid, sometimes light red in color due to blood in the urine. The patient is in pain during peeing and often pees small quantities. In case of a pyelonephritis, a person generally feels a lot sicker than with a bladder infection. The patient has high fever, is sick and has chills. The patient can also have pain in the lower abdomen, back or side.
A distinction is made between acute and chronic pyelonephritis:


In order to determine the diagnosis of pyelonephritis, two laboratory tests are carried out: microscopic examination of a urine sample and a bacterial culture in a urine sample to determine which bacteria are present. A blood test is done to determine whether the number of white blood cells has increased, or that the blood contains bacteria.


Pyelonephritis doesn’t heal on its own. The general practitioner will, depending on the type of bacterium that causes the inflammation, prescribe a course of antibiotics. In addition, the patient can also use a painkiller. Surgery may be necessary if examination demonstrates that there are circumstances that increase the risk of infection, such as a blockage, structural defect or a stone.


Pyelonephritis rarely causes permanent damage. The kidneys usually recover completely. Incidentally, scar tissue remains in the kidney. This can lead to kidney failure.