OVERVIEW

What is renal artery embolism?

Before explaining this disease, let’s first understand two concepts: what is the renal artery and what is embolism. The renal artery is the nutrient-supplying blood vessel of the kidney, and each of the two kidneys in the human body has an independent renal artery. Embolism refers to the phenomenon where substances insoluble in blood circulate with the bloodstream and travel to distant sites, blocking the blood vessel lumen. These substances insoluble in blood are called emboli, which can be solid, gas, or liquid. As the name suggests, renal artery embolism refers to a type of disease where emboli in the blood block the renal artery or its branches, leading to kidney ischemia and necrosis.

Is renal artery embolism common?

It is rare, and some cases are only discovered during postmortem autopsies.

Why is renal artery embolism more likely to occur on the left side?

The abdominal aorta gives off two branches to supply the kidneys, which are the renal arteries. However, the two renal arteries are not completely symmetrical. The left renal artery forms a sharper angle with the abdominal aorta, so acute renal artery embolism is more likely to occur on the left side.

What are the types of renal artery embolism?

It can be classified into thromboembolism, fat embolism, gas embolism, and amniotic fluid embolism.

What are the consequences of renal artery embolism?

The main consequence is impaired kidney function, and in severe cases, nephrectomy may be required.

SYMPTOMS

What are the symptoms and manifestations of renal artery embolism?

Whether symptoms occur and their severity are closely related to the degree, extent, number, location, and speed of renal artery occlusion. The most common symptoms include:

• Flank pain: Persistent colicky pain, severe cases may cause restlessness.

• Hematuria: Gross or microscopic, possibly due to red blood cells entering the collecting system from renal infarction.

• Hypertension: Usually occurs within days of onset but may return to normal after weeks. Rapidly progressive oliguric renal failure may develop in cases of acute bilateral renal artery occlusion. Small branch blockages may be asymptomatic.

CAUSES

What are the common causes of renal artery embolism?

Renal artery embolism is primarily caused by insoluble emboli blocking the renal artery. Based on the source of the emboli, it can be classified into:

• Cardiogenic: The majority of cases, commonly including atrial fibrillation, mural thrombosis after myocardial infarction, atrial myxoma, post-valve replacement thrombosis, and bacterial endocarditis.

• Non-cardiogenic: Such as fat, extracardiac tumors, or amniotic fluid.

DIAGNOSIS

What are the main diagnostic tests for renal artery embolism?

The primary tests include color Doppler ultrasound (commonly referred to as ultrasound), abdominal CT, magnetic resonance imaging (MRI), renal artery angiography, intravenous urography, urinalysis, and blood lactate dehydrogenase (LDH).

Why are these tests performed for diagnosing renal artery embolism? What are their purposes?

Each test has its own advantages and disadvantages, so multiple tests are often required to confirm the diagnosis.

• Color Doppler ultrasound: This test is simple and convenient, and it can detect thrombus in the main renal artery.

• Abdominal CT: CT scans include non-contrast and contrast-enhanced scans. Non-contrast CT often fails to show infarcts due to insufficient density contrast, whereas contrast-enhanced CT uses contrast agents to reveal low-density infarct areas (since infarcted regions lack blood supply, the contrast agent does not highlight them).

• CT and MR angiography: These are the preferred diagnostic methods, as they clearly show vascular occlusion in the affected area and renal artery thrombosis.

• Renal artery angiography: The gold standard for diagnosis, but due to its invasive nature, it is not the first choice.

• Urinalysis: It can detect the presence of red or white blood cells in the urine, serving only as an auxiliary diagnostic tool.

What diseases should renal artery thrombosis be differentiated from? What are the differences?

• Renal or ureteral stones: During stone passage, severe colicky pain may occur on the affected side, but the pain often fluctuates due to stone movement and may be accompanied by microscopic or gross hematuria. Some patients may experience nausea, vomiting, or other gastrointestinal symptoms. Physical examination reveals tenderness upon percussion of the affected kidney. Ultrasound, plain radiography, intravenous pyelography, or CT can help confirm the diagnosis.

• Spontaneous renal rupture: This often occurs secondary to kidney diseases such as large renal tumors or cysts. Symptoms include sudden flank pain, gross or microscopic hematuria, nausea, and vomiting. Physical examination may reveal a palpable mass and muscle rigidity in the affected flank. CT scans can aid in diagnosis.

TREATMENT

How to treat renal artery embolism?

First, pain relief and systemic treatment are crucial, but the main treatment methods include anticoagulation therapy, thrombolytic therapy, and surgical intervention.

• Anticoagulation therapy: Primarily involves the use of anticoagulant drugs, such as warfarin and heparin.

• Thrombolytic therapy: Uses thrombolytic drugs (e.g., streptokinase) to dissolve the embolus. Depending on the administration route, it can be systemic or intra-arterial thrombolysis. The former carries a higher risk of bleeding, while the latter, involving intra-arterial drug injection via interventional therapy, reduces systemic bleeding risks.

• Surgery: Traditional renal artery embolectomy is now less commonly used.

Which department treats renal artery embolism?

Depending on the treatment plan, patients may visit nephrology, vascular surgery, or interventional radiology.## Will renal artery embolism recur?
Depending on the underlying cause, recurrence is possible if the embolus is cardiogenic (e.g., atrial fibrillation). Therefore, treating the primary condition is essential to reduce recurrence.

DIET & LIFESTYLE

What should patients with renal artery embolism pay attention to in daily life?

• Maintain a light and easily digestible diet. Avoid greasy foods, and be mindful of dietary restrictions on spicy and fatty foods.

• Control calorie intake: Caloric intake should be balanced with caloric expenditure. Maintain this balance within the standard weight range through a reasonable, balanced diet and increased physical activity.

• Follow a low-fat diet: Reduce consumption of animal fats and replace them with vegetable oils such as soybean oil, peanut oil, or corn oil.

PREVENTION

What are the preventive measures for renal artery embolism?

• Actively treat underlying diseases: such as atrial fibrillation, etc.;

• Early detection: Pay attention to symptoms like low back pain and hematuria, especially if they persist;

• Early diagnosis: Seek prompt examination at a qualified hospital;

• Early treatment: Treat as soon as possible, as thrombolytic therapy has a time window—beyond this period, the effectiveness declines. The longer the delay, the poorer the kidney blood supply, the more kidney tissue becomes necrotic, and the worse the recovery.