Kidney (renal) Abscess

What happens when bacteria invade a health kidney? The following information should help explain why timely evaluation and proper management are critical for best outcomes.

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What is renal abscess?

An abscess is a localized collection of pus in a hollow area formed by the breaking up of tissues. A renal abscess is one that is confined to the kidney and is caused either by bacteria from an infection traveling to the kidneys through the bloodstream or by a urinary tract infection traveling to the kidney and then spreading to the kidney tissue.

A renal abscess is a very unusual disease, but generally occurs as a result of common problems such as kidney inflammation, stone disease and vesicoureteral reflux. Occasionally, a renal abscess can develop from a source of infection in any area of the body. Multiple skin abscesses and intravenous drug abuse can also be sources of renal abscess. Complicated urinary tract infections associated with stones, pregnancy, neurogenic bladder and diabetes mellitus also put a person at risk for renal abscess.

What are the symptoms of renal abscess?

The person may have fever, chills, abdominal pain, weight loss and a vague feeling of bodily discomfort. Urination may be painful and sometimes the urine is bloody. Occasionally the recognition of the disease might be delayed since the symptoms are vague and the disease is uncommon.

How is renal abscess diagnosed?

The patient often has an increased white blood cell count and bacteria often are present in the blood and urine.

X-ray findings depend on the extent and the duration of the infection. Small renal abscesses can be difficult to recognize. Ultrasounds and CT scans are most helpful in recognizing a renal abscess. CT scans appear to be the diagnostic procedure of choice with an accuracy of about 96 percent. These imaging techniques, which have been available for only two to three decades, have greatly improved the diagnostic ability for this disease.

How is renal abscess treated?

The treatment options for a renal abscess are intravenous antibiotics and drainage of the abscess by an open operation or by inserting a catheter through a needle in the skin overlying the kidney with X-ray guidance. This more recent technique, called percutaneous drainage, has become the more frequent method of drainage. Although drainage has been the traditional method of treatment, patients have been treated successfully during the past decade with intravenous antibiotics and observation when early diagnosis has been made.

What can be expected after treatment for renal abscess?

Earlier diagnoses with modern imaging techniques and less invasive treatment have produced better outcomes. However, occasionally a patient with other illnesses such as diabetes mellitus, will have advanced renal abscess that might lead to serious disease and even death. Patients treated early without much damage to the kidney should have a good outcome. It is necessary to treat the causative factors such as kidney stones, vesicoureteral reflux and other sources of infection to decrease the chances of recurrence of renal abscess. 

Prompt treatment of all urinary tract infections and bacterial infections is an important preventative measure.

Reviewed May, 2004

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Glossary Terms

abscess:
	An accumulation of pus anywhere in the body.
antibiotic:
	Drug that kills bacteria or prevents them from multiplying.
bacteria:
	Single-celled microorganisms that can exist independently (free-living) or dependently upon another organism for life (parasite). They can cause infection and are usually treated with antibiotics.
bacterial:
	Of or pertaining to a bacteria.
bladder:
	The bladder is a thick muscular balloon-shaped pouch in which urine is stored before being discharged through the urethra.
catheter:
	A thin tube that is inserted through the urethra into the bladder to allow urine to drain or for performance of a procedure or test, such as insertion of a substance during a bladder X-ray.
CT scan:
	Also known as computerized tomography, computerized axial tomography or CT scan. A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce cross-sectional images of the body. Shows detailed images of any part of the body, including bones, muscles, fat and organs. CT scans are more detailed than general X-rays.
cutaneous:
	Relating to the skin.
diabetes:
	A medical disorder of increased blood sugar levels that can cause bladder and kidney problems.
diabetes mellitus:
	A condition characterized by high blood sugar resulting from the body's inability to use sugar (glucose) as it should. In type 1 diabetes, the pancreas is not able to make enough insulin; in type 2 diabetes, the body is resistant to using available insulin.
gene:
	The basic unit capable of transmitting characteristics from one generation to the next.
infection:
	A condition resulting from the presence of bacteria or other microorganisms.
inflammation:
	Swelling, redness, heat and/or pain produced in the area of the body as a result of irritation, injury or infection.
intravenous:
	Also referred to as IV. Existing or occurring inside a vein.
intravenous antibiotics:
	Medicine inserted directly into the veins.
invasive:
	Having or showing a tendency to spread from the point of origin to adjacent tissue, as some cancers do. Involving cutting or puncturing the skin or inserting instruments into the body.
ions:
	Electrically charged atoms.
kidney:
	One of two bean-shaped organs that filter wastes from the blood and discharge these waste products in urine. The kidneys are located on either side at the level of the 12th ribs toward the back. The kidneys send urine to the bladder through tubes called ureters.
kidney stone:
	A stone that develops from crystals that form in urine and build up on the inner surfaces of the kidney, in the renal pelvis or in the ureters. (Also see nephrolithiasis.)
kidneys:
	One of two bean-shaped organs that filter wastes from the blood and discharge these waste products in urine. The kidneys are located on either side at the level of the 12th ribs toward the back. The kidneys send urine to the bladder through tubes called ureters.
neurogenic bladder:
	Also called neuropathic bladder. Loss of bladder control caused by damage to the nerves controlling the bladder.
percutaneous:
	To place or perform a procedure underneath the skin. No incision (cutting) is necessary.
percutaneous drainage:
	Draining of fluid by a catheter via the skin.
pus:
	The yellowish or greenish fluid that forms at sites of infection.
reflux:
	Backward flow of urine. Also referred to as vesicoureteral reflux (VUR). An abnormal condition in which urine backs up from the bladder into the ureters and occasionally into the kidneys, raising the risk of infection.
renal:
	Pertaining to the kidneys.
stone:
	Small hard mass of mineral material formed in an organ.
tissue:
	Group of cells in an organism that are similar in form and function.
ureter:
	One of two tubes that carry urine from the kidneys to the bladder.
ureteral:
	Pertaining to the ureter. Also referred to as ureteric.
urinary tract:
	The system that takes wastes from the blood and carries them out of the body in the form of urine. Passageway from the kidneys to the ureters, bladder and urethra.
urinary tract infection:
	Also referred to as UTI. An illness caused by harmful bacteria, viruses or yeast growing in the urinary tract.
urine:
	Liquid waste product filtered from the blood by the kidneys, stored in the bladder and expelled from the body through the urethra by the act of urinating (voiding). About 96 percent of which is water and the rest waste products.
vas:
	Also referred to as vas deferens. The cordlike structure that carries sperm from the testicle to the urethra.

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