A renal abscess, also known as a perirenal or kidney abscess, is a pocket of pus that develops in the kidney tissue. It results from the migration of bacteria from another infection site on the body to the kidneys. Most commonly, a renal abscess if a complication of a urinary tract infection (UTI), often complicated by the existence of some blockage of urine flow.
Causes of Renal Abscess
In addition to being the result of a urinary tract infection and/or kidney stones, a renal abscess can be precipitated by one of the following:
- Skin abscess
- Intravenous drug use
- Kidney inflammation
- Kidney disease
- Reproductive or urinary tract surgery
Risk factors for a renal abscess include having diabetes, having an anatomical abnormality of the urinary tract, or having suffered a physical trauma to the kidney region.
Symptoms of a Renal Abscess
Symptoms of a renal abscess vary, but may include one or more of the following:
- Pain during urination
- Blood in the urine
- Fever and chills
- Abdominal pain
- Tenderness in the back
- Night sweats
- Weight loss
The abdominal pain experienced by patients with a renal abscess in usually felt in the side of the abdomen, and may radiate to the groin or down the leg.
Diagnosis of a Kidney Abscess
Once the doctor has taken a medical history and performed a physical examination, other tests may be administered to check for a possible kidney abscess. These diagnostic tests include the following:
- Blood culture
- Abdominal ultrasound
- Urine culture
- CT scan
Blood and urine cultures are taken to determine the type of bacteria causing the infection. Usually, the culprit is Staphylococcus aureus. Increasingly in recent years, methicillin-resistant Staphylococcus aureus (MRSA) may be to blame.
Treatment of a Kidney Abscess
A kidney abscess, once discovered, is usually treated with direct intervention. Typically, pus from the abscess is drained through a catheter inserted percutaneously (through the skin) or surgically implanted. Intravenous antibiotics are usually administered to clear the infection. If the abscess is especially large, it may have to be mechanically drained during a surgical procedure. If the patient has kidney stones, these will usually have to be removed surgically in order to eradicate the infection.
Risk of a Kidney Abscess
While a kidney abscess can almost always be treated effectively with antibiotics, there is always some small element of risk that the infection will become systemic and the patient will develop sepsis, a life-threatening condition.