Alternate Names: Clot in the renal vein; Occlusion - renal vein

Causes and Risks: Renal vein thrombosis occurs when a blood clot develops in the vein that drains the kidney. This is a fairly uncommon situation that may happen after trauma to the abdomen or back, or it may occur because of a tumor, stricture (scar formation), or other blockage of the vein. It may be associated with nephrotic syndrome.

In some children it occurs after severe dehydration and is a more serious condition than in adults. In children, 90% of renal vein thrombi ocur in infants less than 1 year old and 75% occur in infants under 1 month old, all probably secondary to dehydration.

Renal vein thrombosis should be suspected if symptoms develop after femoral vein cannulation (such as for an angiogram test).

Prevention: There is no specific prevention for renal vein thrombosis. Maintaining fluids in the body to avoid dehydration may help to reduce it’s risk.

Symptoms:

• flank pain or low back pain, may be severe
• urine, bloody
• urine output, decreased

Signs and Tests: An examination is often nonspecific. It may indicate nephrotic syndrome or other causes of renal vein thrombosis.

• A urinalysis may show large quantities of protein in the urine, or red blood cells in urine.
• An abdominal X-ray, abdominal CT scan, abdominal MRI, or abdominal ultrasound may show occlusion of the renal vein.
• Venography (angiography) of the vena cava and/or renal vein may indicate renal vein thrombosis.

Treatment: The treatment is focused on preventing new clot formations and reducing the risk of the clot traveling to other locations in the body (embolization). Anticoagulants may be given to prevent formation of new clots. Bedrest or limited activity may be recommended for a brief period.

Prognosis: Renal vein thrombosis usually resolves over time without permanent injury to the kidneys.

Complications:

• 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 symptoms indicate renal vein thrombosis may be present.

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