The kidneys are located in the flank (back of the upper abdomen at either side of the spinal column). They are deep within the abdomen from the front and are protected in the back by the spine, lower rib cage, and the strong muscles of the back.

This location protects them from many external forces, and they are well padded for a reason -- kidneys are highly vascular organs, which means that they have a large blood supply which could cause severe bleeding, if disrupted.

Kidneys may be injured (renal injury) by damage to the blood vessels that supply or drain them. This may be in the forms aneurysm, arteriovenous fistula, arterial blockage, or renal vein thrombosis.

The extent of bleeding depends on the location and the degree of injury. Kidneys may also bleed profusely if they are damaged centrally (on the inside), and this is a life-threatening injury. Fortunately, most kidney injuries caused by blunt trauma occur periperally, only causing bruising of the kidney (usually a self-limiting process).

People with undiagnosed kidney conditions, such as anigomyolipoma (benign tumor), ureteropelvic junction obstruction (congential or acquired UPJ Obstruction), and other disorders, are more susceptible to kidney injuries and more likely to have serious complications if they occur.

Other causes of kidney injury and bleeding are medical procedures. Kidney biopsies, nephrostomy tube placements, or other surgeries can cause an abnormal connection between an artery and vein (arteriovenous fistula). This is usually a self-limiting problem, but close observation is usually needed.

Injury to the kidney can also cause violation of the urinary tract, causing leakage of the urine from the kidney.

Each kidney filters about 1700 liters of blood per day and concentrates fluid and waste products into about 1 liter of urine per day. Because of this, the kidneys receive more exposure to toxic substances in the body than almost any other organ. Therefore, they are highly susceptible to injury from toxic substances.

Analgesic nephropathy is one of the most common types of toxic damage to the kidney. Exposure to lead, cleaning products, solvents, fuels, or other nephrotoxic chemicals (those which can be toxic to the kidney) can damage kidneys.

Excessive buildup of body waste products, such as uric acid (that can occur with gout or with treatment of bone marrow, lymph node, or other disorders) can also damage the kidneys.

Inflammation (irritation with swelling and presence of extra immune cells) caused by immune responses to medications, infection, or other disorders may also injure the structures of the kidney, usually causing various types of glomerulonephritis or acute tubular necrosis (tissue death).

Injury to the kidney may result in short-term damage with minimal or no symptoms. Alternately, it can be life-threatening because of bleeding and associated shock, or it may result in acute renal failure or chronic renal failure.

Ureteral injuries (injuries to the tubes which carry urine from the kidneys to the bladder) can also be caused by trauma (blunt or penetrating), medical procedures, and other disease processes in the retroperitoneum. The traumatic injuries should be explored, if the patient is undergoing laporatomy for other indicated intra-abdominal injury (and the index of suspicion is high).

Medical therapies (such as OB/GYN surgeries, prior radiation/chemotherapy, and previous abdominopelvic surgeries) are risk factors for ureteral injuries. In other cases, extraperitoneal disease processes (such as retroperitoneal fibrosis (RPF), retroperitoneal sarcomas, or metatstatic lymph node positive cancers) can interfere with normal ureteric processes and cause obstruction/hydroureteronephrosis (swelling of ureter and kidney from urinary backflow).

Acute or emergency symptoms:

• Blood in the urine
• Flank pain, severe
• Abdominal pain
• Back pain
• Nausea, vomiting
• Abdominal swelling
• Fever (sometimes)
• Decreased alertness
  • Drowsiness, lethargy
  • Coma
• Increased heart rate
• Pale skin
• Sweating
• Skin cool to touch
• Decreased urine output
• Inability to urinate

Chronic symptoms:

• Irritability
• Weight loss
• Constipation (with toxic injury, lead poisoning)

A history of physical injury, exposure to potentially toxic substances, or recent infections or illness may indicate the source of injury to the kidney. If there is loss of blood, examination by touch (palpation) may reveal extreme tenderness over the kidney.

There may be signs of hemorrhage and shock, including rapid heart rate and falling blood pressure. Toxic injury or injury from inflammation may cause acute or chronic renal failure.

• A urinalysis may show blood. It may show sediment or crystals that indicate inflammation or toxic accumulations of uric acid or other substances. Part of the urinalysis is an RBC urine test. This may indicate increased red blood cells due to renal tumors, trauma, stones, or necrosis.
• A CBC may indicate bleeding, infection, or inflammation. Other blood tests may reveal toxic levels of suspected substances.
• Electrolyte analysis of the blood may demonstrate increased potassium, urea, or creatinine.
• Kidney X-ray, abdominal CT scan, or abdominal MRI scan may show damage to the kidney.
• A renal scan may indicate problems with kidney blood flow.
• An angiography of the artery or vein may show occlusion of blood flow to or from the kidney.
• An IVP (intravenous pyelogram) may reveal functioning of the kidney. The IVP may be repeated after treatment of kidney injury to assess functioning of the traumatically injured kidney.

Treatment goals include treatment of emergency symptoms and prevention or treatment of complications. Most cases of external trauma result in mild bruises that heal spontaneously.

Analgesics may be needed for pain relief. Hospitalization and close observation may be required because of the risk of internal loss of blood from a traumatically injured kidney.

Approximately 20% of cases of external damage require emergency surgery because of bleeding problems. Bleeding may be severe enough to require surgical removal of the entire kidney (nephrectomy) to control the bleeding. Surgical interventions to control bleeding may include drainage of the space around the kidney. Sometimes angio-embolization is utilized to stop the bleeding.

Surgical repair of a "fractured" or torn kidney, torn blood vessels, torn ureter, or similar injury may spare the kidney from removal. The timing of the surgical exploration depends on the location, the extent of injury, and the overall clinical situation.

For example, if an isolated ureteral injury is discoved a week later, a clinician may divert the urine with the nephrostomy tube, let the inflammation settle down, and elect to operate at a later date for the definitive treatment.

The kidney may return to normal function, or it may experience acute or chronic failure. If only one kidney is affected, there may be no symptoms from the failed kidney, because the second (healthy) kidney functions normally and is adequate for normal health.

Surgical removal or repair of clots or other obstructions may correct injury caused by damage to blood vessels or the ureter.

Nonsurgical treatment of external damage to the kidney may include bedrest for 1 to 2 weeks or until bleeding is reduced, narcotics for pain relief, and close observation and treatment for symptoms of kidney failure.

Exposure to substances, including medications that are suspected of causing injury to the kidney, should be stopped. This may require stopping or changing medications, or it may require a change in occupational or recreational habits. Many cases of toxic injury will reverse when exposure to the substance is stopped.

Some nephrotoxic substances have specific treatments to counteract them. For example, lead poisoning may be treated with chelation therapy, which involves the use of penicillamine, a medication that binds with the lead and allows it to be excreted from the body. Gout and other causes of uric acid accumulation may be treated with allopurinol or similar medications.

Injury caused by infection or inflammation should be treated as appropriate for the specific type of glomerulonephritis or acute tubular necrosis that develops. Treatment may include medications, such as corticosteroids, immunosuppressants, and others.

Treatment may also include dietary restrictions and treatment of acute kidney failure.

The outcome varies depending on the cause and extent of injury. The damage may be mild and reversible, it may be immediately life-threatening, or it may be prolonged and result in complications.

• Pain
• Renal hypertension (even if no other signs of renal failure)
• Infection of the urinary tract
• Infection of other areas (peritonitis, sepsis)
• Bleeding, minor
• Bleeding, severe (hemorrhage)
• Shock
• Acute renal failure, one or both kidneys
• Chronic renal failure, one or both kidneys
• Renal artery stenosis

Call your health care provider if symptoms indicate injury to the kidney or ureter, especially if there is a history of physical injury, exposure to potentially toxic substances, illness, or infection.

Go to the emergency room or call the local emergency number (such as 911) if decreased urine output develops after kidney injury -- this may indicate kidney failure.

External damage may be prevented by using general safety precautions -- using appropriate safety equipment during work and play, wearing seat belts, and driving safely.

Toxic injury often may be prevented by properly observing the directions for use of the medication or product. Follow the directions of the health care provider for use of all medications, including over-the-counter medications.

Use cleaning products, solvents, and fuels as directed in a well-ventilated area because the fumes may also be toxic. Be aware of potential sources of lead poisoning, such as old paints, vapors from working with lead-coated metals, alcohol distilled in recycled car radiators, and similar sources.

Follow the instructions of your health care provider for treatment of gout and other illnesses.