Renal Carbuncle - Causes, Symptoms, Diagnosis, and Management

What Is a Renal Carbuncle?

A carbuncle is a collection of swollen and painful boils under the skin. These boils or furuncles occur due to the infection of the hair follicles and are connected. Usually, a carbuncle is present on the hairy areas of the body, such as the back of the neck. However, they might also be found in other areas like the thigh, groin, and armpits. When these carbuncles occur in the kidneys, they are known as renal carbuncles. Mostly, renal carbuncles are caused by Staphylococcus aureus bacteria. These bacteria enter the skin through the hair follicles and minor injuries and reach the kidneys. Renal carbuncles are usually filled with pus, white blood cells, and dead skin cells. Therefore, they must be treated at the earliest to avoid complications.

What Does the Term Renal Indicate?

The term renal mainly refers to the kidneys present in the human body. They are one of the most crucial organs of the urinary system. A pair of bean-shaped kidneys are present below the rib cage, but both kidneys are present at a slightly different level. The right kidney is lower than the left because the liver occupies the space above the kidneys. The kidneys consist of the renal cortex, renal medulla, and renal pelvis. The main functions of the kidneys are listed below:

• Filters the blood and removes the toxins and waste products from the urine.

• About 120 to 150 quarts of blood are filtered by the kidneys daily.

• Release the hormone renin to maintain the blood pressure of the body.

• Maintain the levels of water and electrolytes within the body.

• Control the production of red blood cells (RBCs) by secreting the hormone erythropoietin.

• Maintain the pH (potential of hydrogen) of the blood.

What Is an Abscess?

An abscess forms when the pus builds up in a particular body area. It can be present externally or on internal organs like the brain, prostate gland, spinal cord, and other genital organs. Normally, the skin acts as the first line of defense against bacteria and infections. However, when the bacteria invade the skin, the body's immune system gets activated. As a result, the cells that work as a policeman of the body, the white blood cells, attack these pathogens, causing the death of the surrounding cells and tissues. When the cells die, a gap is created filled with pus, bacteria, and dead tissues. When the abscess grows, the pressure on the skin increases, causing inflammation of the surrounding organs and tissues. When this abscess develops in the kidneys, it is known as a renal cortical abscess or renal carbuncle.

What Are the Causes of Renal Carbuncle?

A renal cortical abscess or renal carbuncle usually occurs due to bacterial entry into the kidneys. The bacteria can enter the kidneys through the urine or blood and spread to other organs from the kidney tissues. The factors that increase the risk of renal carbuncle are listed below:

1. Nephritis - It is a condition in which the kidneys or their filtration units become inflamed. There are several causes of nephritis, including infections, toxins, and autoimmune diseases. Nephritis increases the risk of abscesses and carbuncles.

2. Kidney Stones - Kidney stones form due to the precipitation of salts and minerals in the urine. These minerals and salts coalesce together and form large masses or stones. These stones obstruct the urine flow and cause urinary retention, providing a medium for bacterial growth. These bacteria give rise to renal abscesses later on.

3. Vesicoureteral Reflux - When there is a change in the path of urine, that is, it flows from the bladder to the ureters and the kidneys; the condition is known as vesicoureteral reflux. It is commonly seen in children and infants and increases the risk of urinary tract infections and abscesses.

What Are the Signs and Symptoms of Renal Carbuncle?

Renal carbuncle is a rare condition, and the patient might be unaware of the condition initially. However, the following symptoms are generally seen:

• Fever.

• Abdominal pain.

• Weakness.

• Nausea, vomiting, and diarrhea.

• The urine flow is restricted so the patient can pass a few drops of urine each time.

• Pain and burning sensation while urinating are commonly seen.

• Urinary incontinence or leakage of urine can occur in some patients.

• The urine appears cloudy and smells bad.

How to Diagnose Renal Carbuncle?

The signs and symptoms of renal carbuncle resemble many other urologic conditions, so it is difficult to diagnose. However, the diagnostic methods have been described below:

• Medical History - It is verbal or written communication between the doctor and the patient. It gives an idea about the symptoms of the condition, the time of their onset, other conditions the patient is suffering from, the medications being taken, and the family history.

• Physical Examination - The doctor checks the physical signs of renal carbuncle. For example, a lump or a mass can be felt on palpating the abdomen.

• Urinalysis - Urinalysis is done to detect the abnormalities in the urine due to a renal carbuncle. The urine sample obtained from the patient is sent to the laboratory for examination under a microscope. Blood, bacteria, and white blood cells in the urine indicate a renal abscess.

• Blood Tests - The doctor recommends the patient undergo a blood test to check the levels of white blood cells. Patients suffering from renal abscess usually present with a high white blood cell count.

• Urine Culture - The patient is asked to collect the urine in a sterile bag or a container provided by the hospital. The urine sample is left unattended in the laboratory for a few days to allow bacterial growth. Patients suffering from a renal abscess will show rapid bacterial growth in their urine.

• Ultrasound - It is an imaging procedure that helps detect renal problems. It is commonly used in pregnant females. The images are obtained on the computer screen. These images help to check the renal abscess.

• CT (Computed Tomography) Scan - It produces three-dimensional (3D) images of the body organs using computer technology and X-rays. In this procedure, the patient is laid on a table, and a liquid (contrast medium) is injected into his body. The table slides into a tunnel-like device where the images are obtained. It is the best method to detect a renal abscess.

How Is a Renal Carbuncle or Renal Cortical Abscess Managed?

The treatment depends upon the abscess and the severity of the infection. Both surgical and non-surgical options are available to manage a prostate abscess, but not all cases require surgery. The treatment options have been described below:

• Antibiotics - Antibiotics remain the first choice when a urinary tract infection or abscess has to be treated. After the diagnostic tests have confirmed that the abscess is less than one centimeter, the following drugs are usually recommended:

  • Levofloxacin.

  • Carbapenem (administered intravenously).

  • Trimethoprim or Sulfamethoxazole.

  • Tobramycin.

• Percutaneous Drainage - It is a method by which the pus present in the abscess is drained by inserting a catheter through the skin. The catheter or the needle is placed under the guidance of a CT scan or ultrasound to drain the infected fluids of the abscess.

What Are the Complications of Renal Carbuncle?

The complications of renal carbuncle are listed below:

1. Acute Renal Failure - When they stop working suddenly, the condition is known as acute kidney failure. It usually occurs when the person is suffering from a disorder that interferes with the blood flow to the kidneys, and the tubes that drain the urine from the kidneys (ureters) are damaged.

2. Sepsis - When a person experiences an infection, the body's immune system responds in an uncontrolled manner that helps fight the infection. However, when this response goes out of control, a life-threatening condition occurs, known as sepsis. It usually happens when the infection persists in the body. Sepsis can affect various organs of the body leading to their failure and, finally, death.

3. Pyelonephritis - The inflammation of the kidneys that occurs due to pathogenic infection is known as pyelonephritis. It is commonly seen in females and can cause permanent damage to the kidneys if not treated at the right time.

Conclusion:

Renal carbuncle is a condition wherein single or multiple abscesses form on the kidneys or their filtration units. The exact reason for the formation of these abscesses is still under research. However, certain urologic conditions increase the risk of renal carbuncles. Kidneys carry out several important functions of the body, and any interference in their functions might affect the quality of life. People suffering from renal carbuncles frequently present with abdominal swelling, but the diagnosis is challenging. However, the patient need not worry because the condition rarely requires surgical intervention, and antibiotics can easily drain the abscess. Consult a urologist to know more about renal carbuncles and their treatments.