What is nutcracker syndrome?
In nutcracker syndrome, the left renal vein is trapped. This vein normally transports blood from the left kidney to the largest body vein in the chest and abdominal cavity, the inferior vena cava (lower vena cava). The left renal vein is usually trapped between the large abdominal artery (abdominal aorta) and a branch of this abdominal aorta – the superior mesenteric artery. The latter transports the blood to the pancreas and into the intestines. More rarely, the left renal vein is compressed at a different location, namely between the spine and the abdominal aorta. In this case, the cause is often a curved spine.
The name comes from the fact that the compression of the left renal vein can be compared to a nutcracker. The abdominal aorta and the upper abdominal artery pinch the renal vein that runs between you. However, we only speak of nutcracker syndrome when this anatomical constriction causes symptoms. If there are no symptoms, the nutcracker phenomenon is the correct technical term. The most common symptoms are lower abdominal pain, which many women initially think of as menstrual cramps. It is also typical that red blood cells (erythrocytes) or blood can be detected in the urine (hematuria). Protein is also found in the urine (proteinuria). In women, the left ovarian vein and in men the left testicular vein flow into the left renal vein. These can expand due to the congestion in the renal vein and swell into varicose veins. In women, varicose veins can develop around the uterus, causing discomfort (pelvic congestion syndrome), and in men, dilated veins around the left testicle (varicocele).
Nutcracker syndrome – frequency and age
Nutcracker syndrome is a very rare clinical picture. It is particularly difficult for general practitioners to recognize because they rarely see patients in their day-to-day practice and the symptoms are difficult to classify. It is not possible to quantify how many people actually fall ill. Many people do not notice the left renal vein being trapped because they do not experience any symptoms. Conversely, some patients experience very pronounced symptoms that result in a high level of suffering and a reduced quality of life.
Women suffer from nutcracker syndrome more often than men. Women between the ages of 20 and 30 and in the fourth decade of life are most frequently affected. They are often tall and slim. But adolescents can also develop nutcracker syndrome, and both sexes. Most cases of compressed left renal veins have so far been found in countries in the Far East.
Nutcracker syndrome: causes and risk factors
The causes of nutcracker syndrome are still unknown. However, there are some risk factors that are thought to play a role in the development of nutcracker syndrome. These include, for example:
- Rapid body growth during puberty
- Low body mass index (BMI) or significant weight loss within a short period of time
- Several pregnancies and births
- Sometimes nutcracker syndrome is associated with certain diseases. Examples: Schönlein-Henoch purpura (inflammation of small blood vessels), IgA nephropathy (disease of the renal corpuscles, the glomeruli) and idiopathic hypercalciuria in nephrolithiasis (increased calcium excretion in kidney stones).
Symptoms: Nutcracker syndrome is painful
The symptoms of nutcracker syndrome are non-specific, can vary considerably and differ greatly from person to person. While children and adolescents often have no symptoms, adults sometimes experience very intense symptoms and suffer enormously. The following signs can occur with nutcracker syndrome:
- Cramp-like lower abdominal pain and flank pain on the left side, which intensifies when sitting or standing; many also localize the pain in the small pelvis or in the area of the testicles or ovaries – the reason for the pain is inflammatory processes triggered by high blood pressure in the left renal vein.
- Hematuria: Excretion of red blood cells or blood in the urine – due to the increased pressure in the left renal vein, the fine venules are destroyed; the hematuria itself does not cause any symptoms.
- Proteinuria: excretion of protein in the urine, particularly detectable in adolescents.
- In men: varicose veins in the left scrotum (varicocele), sperm production may also be restricted.
- In women: severe abdominal cramps during menstruation, pain during and after sexual intercourse, difficulty emptying the bladder, varicose veins in the pelvis, pubic region, buttocks or thighs, emotional disturbances.
- Varicose veins in the legs.
- Pain when urinating.
- Exhaustion syndrome (fatigue): Tiredness, lack of energy, lack of physical performance.
Diagnosis of nutcracker syndrome
Many sufferers find it difficult to categorize their symptoms. Nutcracker syndrome is rare and many lay people have probably never heard of the condition. Women usually classify the symptoms as normal menstrual problems. Even for us, the diagnosis of nutcracker syndrome is often difficult and challenging. Firstly, because the symptoms are so unspecific and can also occur in the context of other diseases. And secondly, because many people have not yet come into contact with the condition due to its rarity.
Some sufferers suffer for a very long time and the diagnosis is often made late. Sometimes the trapped left renal vein can also be discovered by chance during a routine examination, for example an abdominal ultrasound.
The diagnosis always begins with a medical history interview, during which you will be asked a number of questions. For example:
- Which symptoms do you experience exactly and in which areas of the body?
- How long have you been suffering from the symptoms and how severe are they?
- Are there situations in which the symptoms increase, for example when sitting or standing?
- Have you had several births?
- Have you lost a lot of weight recently?
- Do you have any known diseases? If yes: Which ones?
We can already draw some conclusions about the cause of the complaints from your answers. This is usually followed by a physical examination.
If this is suspected, imaging procedures can be used next. The ultrasound examination is the first step:
- Color-coded duplex sonography: The blood vessels in the abdominal cavity can be visualized using ultrasound and the left renal vein and its course can be specifically examined. The size ratios or the blood flow indicate the presence of a nutcracker phenomenon.
Depending on the findings of the ultrasound examination, other imaging procedures may be used to accurately visualize the often altered pelvic, testicular/ovarian veins:
- Computed tomography (CT): An examination using X-rays that provides detailed cross-sectional images of the body, particularly of organs and blood vessels.
- Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA): This method works with magnetic fields and provides high-resolution cross-sectional images of organs, vessels and vessel walls.
- Phlebography (venography): A combined procedure in which the blood vessels are visualized with contrast medium and, if necessary, treatment (stent implantation, foam sclerotherapy) can be carried out immediately.
Nutcracker syndrome: prevention, early detection, prognosis
You can’t really prevent nutcracker syndrome. This is because you cannot influence most of the factors that promote the disease yourself. There are also no special measures for early detection in GP practices. The general advice is therefore: always consult your doctor promptly if you have symptoms for which you cannot identify a reason.
Course and prognosis of nutcracker syndrome
The course and prognosis are good if nutcracker syndrome is diagnosed in good time and treated adequately. Normal everyday life is then usually possible again.
In children and adolescents, the disease often regresses spontaneously due to their growth. In this case, treatment can be delayed for the time being.
Nutcracker syndrome: treatment depends on the severity
The treatment of nutcracker syndrome depends on how severe the disease is and how it progresses. Your age also plays a role in the choice of therapy. In younger patients with a mild course without serious symptoms, the development of the disease can initially be observed for some time. You will then need to see your doctor regularly and have urine tests carried out, for example.