Renal vein thrombosis is a blood clot that develops in the vein that drains blood from the kidney.

Renal vein thrombosis is a fairly uncommon situation that may happen after trauma to the abdomen or back, or it may occur due to:

• Scar formation
• Stricture
• Tumor

It may be associated with nephrotic syndrome.

In some children, it occurs after severe dehydration and is a more serious condition than in adults. Dehydration is the most common cause of renal vein thrombosis in infants.

• Bloody urine
• Decreased urine output
• Flank pain or low back pain

An examination may not reveal the specific problem, but may indicate nephrotic syndrome or other causes of renal vein thrombosis.

• Abdominal CT scan, abdominal MRI, or abdominal ultrasound may show obstruction of the renal vein
• Urinalysis may show large quantities of protein in the urine, or red blood cells in the urine
• X-ray of the kidney veins (venography) may show renal vein thrombosis.

The treatment is focused on preventing new clot formations and reducing the risk of the clot traveling to other locations in the body (embolization).

You may get medications that prevent blood clotting (anticoagulants) to stop new clots from forming. Your doctor may recommend bedrest or limited activity for a brief period.

Renal vein thrombosis usually gets better over time without permanently injuring the kidneys.

• Acute renal failure (if thrombosis occurs in a dehydrated child)
• Embolization of the blood clot to the lungs (pulmonary embolism)
• Formation of new blood clots

Call your health care provider if you have symptoms of renal vein thrombosis.

If you have experienced renal vein thrombosis, call your health care provider if you develop decreased urine output, difficulty breathing, or other new symptoms.

There is no specific prevention for renal vein thrombosis. Maintaining fluids in the body to avoid dehydration may help to reduce its risk.