AUA Summit - What is Kidney (Renal) Trauma?


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What is Kidney (Renal) Trauma?

Kidney (renal) trauma is when a kidney is injured by an outside force.

Your kidneys are guarded by your back muscles and rib cage. But injuries can happen as a result of blunt trauma or penetrating trauma.

  • Blunt trauma – damage caused by impact from an object that doesn’t break the skin.
  • Penetrating trauma – damage caused by an object that pierces the skin and enters the body.

Any type of trauma to the kidney might keep it from working well. It’s important to learn about damage to your kidneys and get immediate care if you need it.

What Happens Under Normal Conditions?

The urinary tract is the body’s drainage system. It includes two kidneys, two ureters, a bladder, and a urethra.

Healthy kidneys work day and night to clean our blood. These 2 bean-shaped organs are found near the middle of the back, just below the ribs. One kidney sits on each side of the spine.

Our kidneys are our body’s main filter. They clean about 150 quarts of blood daily. Every day, they form about 1-2 quarts of urine by pulling extra water and waste from the blood. Urine normally travels from the kidneys down to the bladder and out through the urethra.

As a filter, the kidney controls many things to keep us healthy:

  • Fluid balance
  • Electrolyte levels (e.g., sodium, potassium, calcium, magnesium, acid)
  • Waste removal in the form of urine
  • The regulation of blood pressure and red blood cell counts

When the kidneys are damaged, they may not function well. In most cases, some damage won’t cause too many problems. But, major damage may require more treatment, like dialysis.


Kidney (renal) trauma is when the kidney is hurt by an outside force. There are two types of trauma Blunt and Penetrating Trauma.

Blunt Trauma

The best sign of blunt kidney injury is blood in the urine (“ hematuria”). Sometimes the blood can be seen with the naked eye. Other times, it can only be seen through a microscope.

Blunt trauma kidney injuries may show no outside signs. Or bruises may be seen over the back or abdomen where the kidneys are.

Penetrating Trauma

Penetrating kidney trauma may be suspected when there’s a wound from a knife, bullet or other object that has pierced the skin. But sometimes these wounds may be small or hard to find. Also, sometimes the skin wound is far away from the kidney.


Kidney trauma can occur as kidney injury alone or with other damaged organs. The kidney is the urinary tract organ most often injured by severe trauma.

Blunt trauma can be caused by

  • Car accident (children are especially vulnerable to injury in car accidents)
  • Fall
  • Being hit hard by a heavy object, especially in the flanks (between the rib and the hip)
  • An action where the body comes to a sudden stop after moving quickly

Penetrating trauma can be caused by

  • Bullet
  • Knife
  • Any object piercing the body

Kidney injury is rated on a five-grade scale based on how bad it is. Grade one refers to minor injury, such as bruising. Grade five is the most severe, where the kidney is shattered and cut off from its blood supply.


A simple dipstick urine test can detect microscopic hematuria.

When kidney injury is suspected, it’s vital to do imaging studies of both kidneys. These will confirm the diagnosis and tell how bad the injury is.

Computerized Tomography

A computerized tomography (CT) scan with intravenous (IV) contrast (a special dye) is the best way to assess kidney injury. A CT scan takes many x-ray images that are put together to show “slices” of parts of the body. Injuries can be seen more clearly as the contrast dye flows through the blood and kidney.


Ultrasound can also be used to diagnose kidney trauma. Ultrasound uses sound waves bouncing off structures in your body to create images. But it may not show the best details of the injury.

Intravenous Pyelogram

Intravenous pyelogram (IVP) uses x-rays to show how dye moves through your urinary system. IVP can show how the kidneys are working. The dye is injected into a vein in your arm.


Treatment depends on the condition of the patient, how bad the kidney injury is, and if there are other injuries.

If the patient is stable and there’s no injury to other organs, the trauma might be treated without surgery. The patient will rest in the hospital until no more blood is seen in his/her urine. He/she is watched closely for bleeding and other problems. After leaving the hospital, a patient should be watched for signs of kidney damage like late bleeding or high blood pressure.

If a patient isn’t stable and is losing a lot of blood from the kidney, surgery may be done. Surgery can help the doctor get a better look at the injury. The aim of surgery is to fix and preserve the injured kidney. If the patient needs open surgery to repair other organs, the surgeon will check and fix the injured kidney as well. Sometimes a kidney is too badly injured, so it may need to be removed. Fortunately, kidneys are efficient organs and only one healthy kidney is needed for good health.

Today, most kidney injuries are handled without surgery. Many serious injuries can be treated with minimally invasive techniques. One method is angiographic embolization. Using this method, surgeons can reach the arteries of the kidneys through large blood vessels in the groin to stop bleeding.

After Treatment

The most common problems after treatment are leaking urine or delayed bleeding. These may be treated by using telescopes to reach the urinary tract (“endoscopy”) or angiographic embolization. If these things fail, surgery may be needed. The kidney may need to be taken out.

Another problem is a pus pocket (“abscess”) forming around a kidney. This is treated by draining the infection with a tube placed into the abscess. Sometimes surgery is needed to drain the abscess.

Some patients get high blood pressure after major kidney trauma. This may be treated with medication, interventional radiology (including stent placement), or surgery (including removal of the kidney).

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