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).
