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Renal vein entrapment, or more commonly Nutcracker Syndrome, is a phenomenon occurs when there is an obstruction somewhere along the left renal vein that prevents the circulation from passing through unopposed into the inferior vena cava and eventually, back to the heart. The reason why this happens is a medical mystery but it is believed that abnormal organogenesis during fetal life is the root of the problem. Organs may be fully healthy and functional but because of abnormal anatomical positioning, this can cause vascular congestion and lead to this compressed left renal vein. 

Nutcracker syndrome can be further divided into two distinctive classes depending on how the obstruction presents. Anterior nutcracker syndrome is a much more common occurrence and results when the left renal vein is compressed between two arteries: the abdominal aorta and the superior mesenteric artery. The less common of the two is posterior nutcracker syndrome and this form occurs when the left renal vein is compressed between the abdominal aorta and the bones of the spine. 

This syndrome is impossible to quantify in terms of incidence because it is such an unusual presentation. It is very hard to diagnose even with medical imaging and patients must often hunt for years before finally being diagnosed with the condition. 

Based on our current knowledge about this disease, there is no genetic link that we know of predisposing family members to the disease. In order to make an accurate diagnosis, the most important thing for a physician to be aware of the symptoms that can be present when a patient first shows manifestations of Nutcracker syndrome. This disease can occur anytime during a person's life but the highest incidence of this disease can be found in adults in their 20s-30s. 

Symptoms can fluctuate quite drastically and it is not uncommon for patients to be completely asymptomatic at first. Children are the most likely group to have no symptoms. On the other spectrum of presentation, patients may have severe pelvic pain and macrohematuria and these symptoms can become worse after physical activity. This disease will typically present as an isolated episode of microhematuria at first in pediatric populations. According to current data, 69 percent of the time, we will not be able to identify what caused this. Of these, Nutcracker Syndrome was diagnosed in 40 percent after a renal ultrasound was done. Some less common symptoms include varicoceles, orthostatic proteinuria and dilated gonadal veins. 

To confirm a diagnosis of this disease, patients will need to have imaging and laboratory studies in order to solidify the diagnosis. Renal venography and ultrasounds are a key to observing this compression and blood tests can show abnormal kidney function to help raise our suspicion. Patients should also be tested for urinary tract infections to rule out any other possible causes of hematuria. Tomography may be done but it is possible to have no changes so insist further studies if CT scans are inconclusive still. 

When it comes to treatment, there is also one of several approaches that a physician can take depending on the severity of the disease. Mild cases of Nutcracker syndrome can resolve spontaneously and only conservative management for microhematuria is needed. ACE inhibitors work great at lowering venous pressure and protecting your kidney function. There patients will be followed for at least 2 years and symptoms can resolve in 75 percent of cases. 

In cases where conservative therapy is not possible or if things do not get better after 2 years of therapy, more aggressive options must be considered. Stents, vascular surgeries to bypass the occlusion or even kidney transplants are all options that could be considered depending on the severity and persistence of a patient's case. In most cases, physicians will recommend a combination of multiple advanced techniques because although stents are great for short-term improvements, it is possible for them to fail. Open surgeries to address the occlusion more directly seem to have a better long-term outcome for the patient. 

It is important to begin treatment as soon as you can because the longer you deal with this venous engorgement, the more likely you may have renal thrombosis. Emboli will block your circulation and can leave you with permanent kidney damage that will require a transplant. 

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