Nutcracker Syndrome : Causes, Risk Factors, Symptoms, Treatment and Recovery

Nutcracker syndrome is a condition in which the left renal vein gets compressed by two arteries and this interferes with the blood flow out of the left kidney. It is named a nutcracker as the compression resembles a nutcracker cracking a nut.

Nutcracker syndrome does not always cause symptoms, but the people experiencing it may sometimes experience left flank pain and blood and protein in the urine due to an increase in pressure due to the backward flow of blood.⁽¹⁾ It may also sometimes lead to kidney damage, anemia, and infertility.

Nutcracker syndrome is of two main types:⁽¹⁾

• Anterior Nutcracker Syndrome: It involves compression of the left renal vein between the abdominal aorta and another artery. It is a common type.
• Posterior Nutcracker Syndrome: It is a less common type and involves compression of the left renal vein between the abdominal aorta and the spine.

A mixed type is also identified by the researchers which involves changes to the blood vessels.⁽²⁾

Nutcracker syndrome occurs due to the compression of the left renal vein, which can occur due to the following:⁽³⁾

• Injury
• Tumor
• Anatomic irregularities
• Pregnancy
• Aneurysm in the abdominal aorta

Nutcracker syndrome can be experienced by a person of any age or sex but is more common in females in their 30s or 40s. In children, it may occur after rapid growth during puberty. In children, it may lead to mild symptoms and may often resolve without treatment.

The symptoms of nutcracker syndrome may depend on the extent and place of compression. Some people may not suffer from any symptoms at all.

The symptoms of nutcracker syndrome include:

• Blood in urine
• Kidney damage
• Pain in the left flank
• Protein in urine
• Varicose veins
• Urinary tract infection
• Enlarged vein in the testicles in males
• High blood pressure

To diagnose the nutcracker the doctor needs to take the complete medical history and perform a physical examination.

A urine test is ordered to look for complete blood and protein in urine and a blood test, to check the blood cell count and kidney function.

Imaging tests can also be ordered to look for vascular blockages and abnormalities. These include:

• CT scan
• Doppler ultrasound
• MRI scan

If a person experiences mild symptoms, simply observing the symptoms is recommended by the doctor to see if they resolve.⁽⁴⁾ If the symptoms are observed to be not improving, low-dose aspirin and angiotensin-converting enzyme ACE inhibitors are recommended.

Surgical options for nutcracker syndrome include the following:

• Venous Stenting: It involves inserting a small tube or stent into the left renal vein to keep it open.
• Blood Vessel Surgery: It involves rerouting the blood vessels with the help of grafts or moving compressed vessels.
• Nephrectomy: In this, the affected kidney is removed. This is an appropriate option when other treatment options fail.

People undergoing surgery would need several weeks to recover. Recovery time for each individual depends on the health condition of an individual and the type of surgery. Those undergoing venous stenting recover quicker than those undergoing complex procedures such as nephrectomy.

Even after surgery, a kidney function test may be ordered to look for the glomerular filtration rate. If a person undergoes nephrectomy, the eGFR may take months to recover⁽⁵⁾

A person if undergone surgery for treatment may need to take a blood thinner or undergo more surgeries.

Nutcracker syndrome resolves spontaneously in most cases, especially in children.⁽³⁾

If not treated, nutcracker syndrome may lead to the following symptoms:

• Kidney damage
• Blood clot in the left renal vein
• Pelvic congestion syndrome in females
• Infertility in males due to varicocele and females due to pelvic congestion syndrome
• There may be anemia due to blood loss in the urine

There may be complications after surgery, which include:

• Blood clots
• Infection
• Kidney damage
• Blocked flow of blood

Nutcracker syndrome is the blockage of the left renal vein, restricting blood flow and causing symptoms such as left flank pain and blood and protein in the urine. It is important to get treated at the earliest to avoid complications.