The kidney is injured more often than any of the organs along the urinary tract. Blunt force due to motor vehicle collisions, falls, or sports injuries is the usual cause of injury. Penetrating kidney injuries can result from gunshot or stab wounds. Less commonly, injuries can occur during diagnostic tests, such as a kidney biopsy, or during various treatments, such as those for kidney stones, including extracorporeal shock wave lithotripsy. Most blunt kidney injuries are minor. However, some are serious. If serious blunt or penetrating kidney injuries are not treated, complications, such as kidney failure, high blood pressure, delayed bleeding, and infection, may result.
Symptoms and Diagnosis
Symptoms of a blunt kidney injury may include pain in the upper abdomen or flank (the area between the ribs and hip), bruising of the flank, blood in the urine, marks near a kidney made by a seat belt, or pain resulting from fractures of the lower ribs. With severe kidney injuries, low blood pressure (shock) and anemia may occur if the person loses a significant amount of blood.
The history of events that led to the injury, the person's symptoms, and a physical examination help doctors recognize kidney injuries. A sample of urine is taken and examined to see whether blood is present. Blood in the urine in a person with an injury to the trunk suggests that the injury involves the kidney. The blood may be visible with the naked eye (gross hematuria) or visible only using a microscope (microscopic hematuria). With penetrating injuries, the location of the wound (whether in the upper or mid part of the abdomen, back, or flank) may help doctors determine whether the kidney is involved.
Adults who have mild symptoms and blood in the urine that is visible only with a microscope probably have a minor bruise that will heal on its own. Further tests are usually not needed. For children, and for adults in whom doctors suspect a more serious injury, computed tomography (CT) with radiopaque dye (contrast agent) is done. Occasionally, additional imaging tests may be needed to confirm the diagnosis.
For minor kidney injuries, careful control of fluid intake and bed rest are often the only treatment needed, because these measures allow the kidney to heal itself. For more serious injuries, treatment begins with steps to control blood loss and to prevent shock. Fluids and sometimes blood are given intravenously to help keep blood pressure within a normal range and stimulate urine production. Only the most serious injuries, such as when the kidney is torn from its attachments to blood vessels, require surgical repair. Rarely, the injured kidney needs to be removed.
Most people recover from even serious kidney injuries, provided the injuries are diagnosed and treated promptly. Kidney failure, when it develops, may require lifelong treatment. Other complications of kidney injuries that require treatment include high blood pressure, delayed bleeding, and infection.
Last full review/revision June 2007 by Noel A. Armenakas, MD