A kidney contusion, often called a kidney bruise, occurs following blunt trauma or direct impact to the lower back. This trauma leads to bleeding inside of the kidney. It may also cause pain, tenderness, and discoloration of the skin.

Your back muscles and rib cage protect your kidneys. If a kidney becomes injured, you may also have injured other muscles and bones.

A bruised kidney is considered a serious injury. Left untreated, it can lead to serious health complications, even death.

The common symptom associated with a bruised kidney is pain, specifically on the sides of the abdomen and in the flank area. This is the region between the lower rib cage and upper hip.

Other symptoms include:

In more severe cases, a bruised kidney can lead to serious health complications, such as:

Blunt force trauma to the back or abdomen is a common cause of kidney bruising. This type of trauma can happen during a car accident or a bad fall. A direct hit or kick in the lower back, particularly within sports, can also cause kidney bruising.

Treatment depends on the cause and resulting symptoms. Before providing treatment, your doctor will run tests to diagnose the condition and rule out other health complications.

Your doctor will examine your physical symptoms and ask about your medical history. They may then conduct imaging tests to rule out internal bleeding and further injury, such as:

In milder cases, your kidney will heal on its own within one or two weeks. Your doctor may recommend bed rest during this time to closely monitor your condition.

In more serious cases, your doctor may administer fluids to maintain blood pressure. Controlling your fluid intake will also encourage urine production if it’s been affected by your injury. Your doctor will also address internal bleeding issues.

If your doctor can’t control your bleeding, you may need surgery.

A bruised kidney is a serious injury that often requires immediate medical attention. If the injury was minor, it can take up to two weeks for a bruised kidney to heal on its own. Even with mild symptoms, kidney injuries can progress into serious complications and may cause internal bleeding.

If you were in an accident that injured your back or abdomen, call your doctor to discuss your kidney health. Though kidney bruising can heal on its own, professional observation is important to ensure further issues don’t develop.