Nutcracker syndrome is a rare condition that happens when the vein that drains your left kidney gets squeezed between big blood vessels in your belly. It can be very painful, but it's usually not serious.
Most often, your left kidney vein is pressed between your aorta (which carries blood from your heart) and your superior mesenteric artery (which sends blood to your gut). This is called anterior nutcracker syndrome.
Less commonly, the vein gets pinched between your aorta and your spine. This is known as posterior nutcracker syndrome.
In both cases, increased pressure can slow your blood flow, or cause your blood to flow the wrong way. This can cause pain, or blood in your pee. A doctor familiar with the condition can help you decide what to do next.
"Don’t panic," says Caitlin Hicks, MD, a vascular surgeon and associate professor of surgery at Johns Hopkins University School of Medicine. "Getting in to see a specialist who can talk about your options is important, but oftentimes, symptoms self-resolve over time."
What Are Symptoms of Nutcracker Syndrome?
You may not feel much at first. But if the vein stays squeezed for a long time, it can cause:
- Blood in your pee (hematuria)
- Pain in your left side or lower back (flank pain)
- Belly or pelvic pain
You may also have:
- Constant tiredness
- Headache
- Dizziness when you stand up
When blood can’t flow well through your kidney vein, it may back up into other veins – like the ones in your pelvis. That can cause different symptoms based on your body.
Nutcracker symptoms in women (people born with a uterus and ovaries) may include:
- Painful periods
- Pain during sex
- Pain with peeing
- Swollen pelvic veins (called pelvic congestion syndrome)
Nutcracker symptoms in men (people with testicles) may include:
- Swollen veins in the scrotum (called varicocele)
- A heavy feeling or pain in the testicles
Symptoms may flare with movement, certain body positions, or during your period. "Most of the time, it’s not a constant state of pain," Hicks says. "It does tend to be cyclical for whatever reason."
Nutcracker Phenomenon vs. Nutcracker Syndrome
Nutcracker phenomenon is when there’s compression on your kidney vein, but you don’t have symptoms. Nutcracker syndrome means the vein is squeezed and you have symptoms.
Doctors don’t treat the phenomenon, and you usually don’t need checkups unless symptoms show up later. If they do, talk to your regular doctor or a vascular surgeon about next steps.
What Causes Nutcracker Syndrome?
You don’t have to do anything "wrong" to get it. Common causes include:
- A narrow angle between your blood vessels
- Low belly fat, either from being thin or after weight loss
- Growth spurts, especially during your teen years
These things can make the space between your arteries too tight. That area normally has enough room and fat to help cushion the vein. If that padding shrinks or the blood vessels shift, the vein can get squeezed.
Less common causes include:
- Tumors near your pancreas or deep in your belly
- Swollen lymph nodes
- An enlarged aorta
- Bands of tissue that press on the vein
- Pregnancy (as the uterus swells and pushes on nearby veins)
- Spine problems, like a deep curve in your lower back
Who gets nutcracker syndrome?
Anyone can get it, including middle-aged and older adults. But doctors see it most often in younger people, especially in the late teens to early 20s. It also seems to be more common in women, or people assigned female at birth.
How common is it?
It’s hard to say. Doctors think it's rare, but they don't know how many people have it.
Is nutcracker syndrome something you’re born with?
It can be. Some people are born with a narrower angle between the arteries, which raises the chance that the kidney vein will get compressed. These changes may not cause problems at first, but symptoms may show up during times of growth or weight change.
Can weight loss cause nutcracker syndrome?
It might. Losing weight, especially fast, can shrink the fat pad that protects the vein. Without that cushion, the arteries may press down on the vein more easily. That’s why some people notice symptoms after a growth spurt or weight loss surgery.
How Do You Diagnose Nutcracker Syndrome?
Nutcracker syndrome isn’t always easy to spot. Symptoms like pain, blood in your pee, or pelvic pressure can look like more common health problems. That’s why doctors usually start by ruling out other causes, such as kidney stones, urinary tract infections, or endometriosis.
If your doctor thinks nutcracker syndrome might be the cause, they’ll check for signs that your kidney vein is being squeezed.
These are some of the tests you might need:
Urinalysis. This simple pee test looks for blood, even tiny drops you can’t see with your eyes.
Doppler ultrasound. This noninvasive test uses sound waves to check how fast blood moves through the kidney vein. It can’t diagnose nutcracker syndrome, but it can offer clues.
CT angiography (CTA) or MR angiography (MRA). These scans give a clear picture of the blood vessels in your belly. They show if the vein is narrow and whether blood is backing up or rerouting.
Venogram with pressure check. A thin tube goes into your vein to measure pressure before and after the tight spot. A big change in pressure is a strong sign the vein is being squeezed. During a venogram, your doctor may also use an intravascular ultrasound (IVUS) to get a closer look inside the vein.
Nutcracker Syndrome Treatment
Treatment depends on how much your symptoms affect your daily life. Some people feel better with time and simple care. Others may need surgery to fix the compressed kidney vein or treat the swollen veins that come with it.
Watchful waiting and symptom relief
If your symptoms are mild, your doctor may suggest:
- Over-the-counter pain relievers like acetaminophen or ibuprofen
- Medications that help your kidneys, like ACE inhibitors or aspirin
- Tracking symptoms to see how they change
- Imaging or urine tests to monitor your condition
If weight loss may be part of the cause, your doctor might suggest gaining a small amount back. "We don’t prescribe massive weight gain," Hicks says. "But if people have lost five pounds and their symptoms have gotten worse, gaining those five pounds back might help."
In young people, the watch-and-wait approach is usually enough. "Kids who are at the end of their teenage years often grow out of it," Hicks says.
Procedures and surgery
If your symptoms don’t go away or seriously impact your life, your doctor may talk to you about more direct options. That could mean fixing the kidney vein itself or treating the swollen pelvic veins that can happen because of the pressure.
The best choice for you depends on:
- Your age and general health
- Which symptoms bother you most
- How serious your symptoms are
- Whether you’ve had surgery before
Surgeries for nutcracker syndrome include:
Renal vein transposition. Your doctor moves the squeezed vein to a better spot with more space. This is the most common surgery for serious symptoms. It can ease flank pain for 80% to 90% of people with this condition.
Stenting. A small tube goes inside your renal vein to keep it open. This may help, but it’s not the top choice for younger people. "Stents aren’t meant to last forever," Hicks says. "If you put one in a 20-year-old, the likelihood of that lasting until their 80s is pretty low."
Gonadal vein embolization. This treats swollen pelvic veins by blocking or rerouting blood flow. It may help if pelvic symptoms are your biggest issue, especially in people with pelvic congestion.
Renal auto-transplant. Your doctor removes your kidney and moves it to a new place in the body. This is usually only done if other surgeries haven’t worked and your symptoms are still really bad.
Takeaways
Nutcracker syndrome is a rare condition where a vein from your left kidney gets squeezed, usually between two big blood vessels. This slows blood flow and causes symptoms like left-side pain, blood in your pee, or pelvic pain and pressure.
Mild cases often get better with time, especially in teens and young adults. But if your symptoms stick around or get worse, tell your doctor. Rarely, untreated nutcracker syndrome can lead to other health problems, like kidney damage or blood clots.
Nutcracker Syndrome FAQs
How long does nutcracker syndrome last?
There’s no exact timeline. For kids and teens, symptoms may go away as their body grows and blood vessels shift naturally. But nutcracker syndrome can be a lifelong problem. If it doesn’t go away, treatment can help.
What mimics nutcracker syndrome?
It can seem like kidney stones, urinary tract infections, endometriosis, May-Thurner syndrome, or pelvic congestion syndrome. Some people are first diagnosed with other vein conditions, like superior mesenteric artery syndrome or median arcuate ligament syndrome.
Can nutcracker syndrome go away on its own?
Yes, especially if you’re a kid. Nutcracker syndrome may go away as you grow taller or gain weight. This shift can naturally change the angle between your aorta and superior mesenteric artery, easing pressure on your left renal vein.
Where do you feel nutcracker pain?
Pain usually shows up in the left side of your lower back, near your kidney. You might also feel a deep, aching pain in your belly or pelvis. Symptoms may get worse during or after exercise. It might cause testicle pain, general pelvic pain, or pain with periods.
Does eating make nutcracker syndrome worse?
It might. Some people say their symptoms (like pain or pelvic pressure) get worse after meals. That’s likely because eating increases blood flow to your gut, which can put more pressure on the vein that’s already being squeezed.
What kind of doctor treats nutcracker syndrome?
You might start with a urologist. That’s a doctor who specializes in the urinary system and kidneys. But if you need treatment for blood vessel problems, you’ll likely need to see a vascular surgeon or interventional radiologist.
What are the long-term effects of nutcracker syndrome?
Rarely, constant pressure on the left renal vein can lead to kidney damage or blood clots. It may raise your odds of infertility if you have swollen blood vessels in or near your scrotum or ovaries. With the right care, long-term problems can be prevented.