Renal vein thrombosis

What is renal vein thrombosis?¹

Renal vein thrombosis describes the presence of thrombus in the major renal veins or their tributaries. This may either present with acute symptoms or go unnoticed because of lack of symptoms until a complication such as pulmonary embolism or worsening renal function occurs.

How common is renal vein thrombosis? (Epidemiology)¹

• The overall prevalence is unknown, as renal vein thrombosis is probably underdiagnosed.

• Males are affected more commonly than females. There is no racial predilection. Almost two thirds of patients have bilateral renal vein involvement. In cases of unilateral thrombosis, the left renal vein is more often affected than the right.

• it is rare in children and usually due to severe illness, eg, asphyxia, severe infection, dehydration. However, renal vein thrombosis is the most common spontaneous thrombosis in neonates.²

Aetiology

Nephrotic syndrome and membranous nephropathy are the most common causes.¹ Other causes include:

• Renal cancer.

• Renal transplantation. Transplant renal vein thrombosis usually occurs early after surgery with a reported prevalence of 0.1-4.2%. It ultimately leads to graft loss in almost all cases. The presentation of acute renal vein thrombosis is nonspecific and similar to the features of urine leak, urinary obstruction, or severe acute rejection.³

• Behçet's disease.

• Hypercoagulable states.⁴

• Antiphospholipid syndrome.

Renal vein thrombosis symptoms (Presentation)

Symptoms may be difficult to differentiate from those of the underlying condition, eg, nephrotic syndrome or renal malignancy:

• Acute: loin pain, decline in renal function, haematuria, renal enlargement, asymmetrical leg oedema, increased proteinuria in nephrotic syndrome.

• Chronic: there may be no symptoms or signs and it is detected by decline in renal function, increase in proteinuria or by being seen on abdominal MRI scan.

• Other features of both acute and chronic forms are pulmonary emboli, increased peripheral oedema, dilated abdominal veins, left varicocele (if the left renal vein is thrombosed).

Differential diagnosis

In the absence of any clearly identifiable underlying cause, it should be considered as a possible cause of:

• Acute kidney disease.

• Chronic kidney disease.

• Increased proteinuria or decline in renal function in patients with nephrotic syndrome.

• Pulmonary emboli with no lower limb deep vein thrombosis.

Investigations

• Serum creatinine and urinary protein (unexplained decline in renal function or sudden increase in proteinuria). Other laboratory investigations will depend on the clinical situation, eg, for nephrotic syndrome.

• Doppler ultrasound scan.

• Intravenous pyelogram (IVP) findings are rarely specific but may show an enlarged kidney. If the renal pelvis is observed, it is usually distorted. A characteristic but uncommon finding is notching of the ureter, caused by tortuous collateral veins near the ureters.

• Inferior vena cavography can be diagnostic but otherwise will need selective renal vein catheterisation to be performed.

• Renal arteriography may be useful in cases of renal trauma or tumour, when renal artery involvement is common.

• Renal ultrasound is usually not sensitive enough to assist in making the diagnosis.

• CT or MRI scanning is currently the procedure of choice for non-invasive diagnosis. They may also help detect the presence of a tumour.

• Renal biopsy is essential in evaluating patients with nephrotic syndrome.

Associated diseases

• Glomerulonephritis (especially if it causes nephrotic syndrome) - most commonly membranous glomerulonephritis,⁵ but may also be associated with membranoproliferative, minimal change or rapidly progressive glomerulonephritis. Also systemic lupus erythematosus (SLE) and amyloidosis.

• Renal cell carcinoma - by extrinsic pressure on the renal vein or invasion of the renal vein or inferior vena cava. May also be due to extrinsic compression by any other tumour or retroperitoneal mass.

• Trauma.

• Dehydration, especially in infants.

• Hypercoagulable states.

• May be associated with thrombocytopenia.

• Post-renal transplantation.

Renal vein thrombosis treatment and management

• Anticoagulation.

• Thrombolysis therapy to break down the blood clot.

• Statins, angiotensin-converting enzyme (ACE) inhibitors or angiotensin-II receptor blockers decrease proteinuria from nephrotic syndrome.⁶ Decreasing protein loss in the urine decreases hypercoagulability.

• Treatment of any underlying associated disease.

Surgical

• Surgical treatment is rarely required.

• Inferior vena caval filters may be used in bilateral renal vein thrombosis.

• Surgery may be necessary for renal vein thrombosis caused by renal cell cancer.

Complications¹

• Recurrent thromboembolism, eg, pulmonary embolus.⁷

• Acute kidney injury.

• Chronic kidney disease.

• Hypertension.

• Complications specific to the underlying cause, eg, graft failure after renal transplantation.

Prognosis¹

• Prognosis is variable. Renal vein thrombosis may resolve spontaneously or result in hypertension and renal failure.

• Prognosis also depends on age and comorbidities, as well as the underlying cause.

• Prognosis is determined by the effects on nephrotic syndrome, renal dysfunction or the complications resulting from thromboembolism.

• Prognosis of any underlying cause is worsened by the onset of acute renal vein thrombosis.

• Acute thrombus formation adversely affects graft survival after renal transplantation.

Prevention

See the separate article Prevention of Venous Thromboembolism.