Nutcracker syndrome is a rare vein compression disorder. It occurs when arteries, most often the abdomen’s aorta and superior mesenteric artery, squeeze the left renal (kidney) vein.
It can cause many symptoms in both children and adults, such as flank pain and blood in the urine. Common treatments for nutcracker syndrome include stenting, surgery, and routine urine tests.
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Nutcracker syndrome is a variation of nutcracker phenomenon or renal vein entrapment syndrome, in which the arteries near the kidney compress the left renal (kidney) vein.
In most cases, compression of the left renal vein is between the abdominal aorta — the main artery in the abdomen — and the superior mesenteric artery, which brings blood to the pancreas and intestines.
Nutcracker syndrome gets its name because this compression is like a nutcracker crushing a nut.
Normally, the left renal vein brings blood out of the left kidney and into the inferior vena cava, the body’s largest vein.
Compression of the left renal vein can cause blood to flow backward into other nearby veins and make them swell. This causes symptoms like flank pain and blood in urine.
Nutcracker syndrome is a rare disorder that can affect adults or children, though the prevalence and specific causes are unknown.
It's more common in women in their 30s and 40s who are tall and slim. Symptoms may appear after rapid weight loss.
Most people with nutcracker syndrome have abdominal pain but this condition can be present — especially in children — without any symptoms. Nutcracker syndrome is not hereditary, though it may be triggered by multiparity or pregnancy.
Nutcracker syndrome has many symptoms for both adults and children, although some – especially children – don’t have any symptoms.
The most common symptoms of nutcracker syndrome can include:
Other symptoms of nutcracker phenomenon can include:
Nutcracker syndrome can be challenging to diagnose because its symptoms can be like other urologic or gynecologic disorders.
Doctors often diagnose nutcracker syndrome after ruling out other conditions.
To diagnose nutcracker syndrome, your UPMC doctor will:
Your UPMC doctor will also take any physical abnormalities or differences into account when diagnosing nutcracker syndrome.
To rule out other common renal conditions, your doctor will perform the following in order:
To confirm a nutcracker syndrome diagnosis, your doctor may order tests such as:
Nutcracker syndrome treatments can vary based on your age, symptoms, and the severity of your condition.
In some cases, you may not need treatment, particularly if you're:
The most common treatments for nutcracker syndrome are:
Your UPMC doctor will discuss each option with you.
Your surgeon may choose to treat your nutcracker syndrome using a stent — a small mesh tube — to hold your left renal vein open and allow for proper blood flow.
To place the stent in your vein, your surgeon will:
In most cases, you’ll stay in the hospital overnight after the procedure.
In some severe cases of nutcracker syndrome, your doctor may suggest vascular surgery to relieve the pressure on your left renal vein.
Surgical treatment for nutcracker syndrome can include moving the left renal vein and reattaching it, or a left renal vein bypass.
Your doctor may recommend surgical treatment of nutcracker syndrome for the following reasons:
Some people with a mild case of nutcracker phenomenon may prefer to postpone invasive treatments and monitor the condition with regular urinalysis. If you choose this option, your doctor will track your condition with regular urinalysis.
Since this is a condition that may improve on its own with time, regular urinalysis let your doctor know if the phenomenon improves or when to take next steps.
In severe cases of nutcracker syndrome, pain and other symptoms are often alleviated right away. In mild cases, the improvement is less obvious.
Last reviewed by a UPMC medical professional on 2024-10-01.
