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Overview. Nutcracker phenomenon is a vascular condition where there is compression of the left renal vein most commonly between the aorta and superior mesenteric artery. This anatomy forms the shape of a nutcracker on sagittal view of cross-sectional imaging. Nutcracker syndrome is the clinical manifestation of the nutcracker phenomenon. The increased left renal vein pressure can lead to left flank pain and gross hematuria. It can also lead to re-routing of venous blood flow through collateral veins and backflow of venous blood into other organs resulting in symptoms such pelvic pain, dysmenorrhea in women and testicular pain in men. 1 Although not life-threatening, nutcracker syndrome can limit patient quality of life due to severity of symptoms. Symptomatic patients may undergo imaging tests to diagnose nutcracker syndrome. Once diagnosed, many patients are observed, although some patients may require intervention depending on the severity of symptoms.2 Patients are often evaluated by a multidisciplinary team of specialists from Interventional Radiology, Vascular Surgery and Urology.
Causes. Nutcracker syndrome can have a variety of clinical presentations with no uniform diagnostic criteria. This frequently leads to delayed or incorrect diagnoses. Most often caused by compression by the aorta and superior mesenteric artery, nutcracker syndrome can be more prevalent with significant lack of abdominal fat, during growth in children and adolescents, and with spine conditions such as lordosis of the lumbar spine. It can also be caused by cysts or tumors of the pancreas, retroperitoneal tumors, swelling of the lymph nodes around the abdominal aorta, or aneurysm of the abdominal aorta. 4
Common Signs and Symptoms.
- Left flank pain
- Blood in urine
- Pain in lower left abdomen
- Pelvic and abdominal pain worse during menstruation in women
- Pain and swelling of the scrotal veins in men
- Fatigue and headaches
- Symptoms may vary with position
Test and Images. Your doctor will go through your medical history and symptoms, may conduct a physical exam, and may order any of the following diagnostic studies for nutcracker syndrome or to rule out other conditions with similar symptoms. 3
- Urine tests screen for a variety of other pathologies that may be causing symptoms
- Cystoscopy may be done to rule out pathologies of the lower urinary tract
- Renal biopsy may be done to rule out any pathologies of the kidney
- Doppler ultrasound helps visualize blood flow through the compressed vein
- CT and MRI angiography allows to visualize narrowing of the compressed vein
- Venography with intravenous ultrasound and pressure gradients helps visualize and quantitate the extent of obstruction through the compressed vein
Treatment Options. Patients with mild symptoms may be observed. Children may be given time to grow and weight gain can help others. For patients with severe symptoms, one of several procedures may be recommended based on anatomy, symptoms, age, and odds of symptom relief. 3
- Open or laparoscopic/robotic surgery involving repositioning of the renal vein in a way that frees it from compression (renal vein transposition)
- Open or laparoscopic/robotic surgery involving bypass of the compressed renal vein
- Autotransplantation of the left kidney to the pelvic vessels
- Endovascular approaches including placing a stent in the left renal vein
Prognosis and Outcome. Although nutcracker syndrome is rare, timely diagnosis and treatment is crucial for avoiding complications such as long-term kidney disease, thrombosis of the renal vein, or development of collateral veins. 4 When appropriate, treatment of the renal vein compression through conservative or interventional approaches can improve symptoms in the majority of patients. 4
References. 1. Kurklinsky AK, Rooke TW. Nutcracker phenomenon and nutcracker syndrome. Mayo Clin Proc. 2010 Jun;85(6):552-9. doi: 10.4065/mcp.2009.0586. PMID: 20511485; PMCID: PMC2878259. 2. Gulleroglu K, Gulleroglu B, Baskin E. Nutcracker syndrome. World J Nephrol. 2014 Nov 6;3(4):277-81. doi: 10.5527/wjn.v3.i4.277. PMID: 25374822; PMCID: PMC4220361. 3. Said SM, Gloviczki P, Kalra M, Oderich GS, Duncan AA, D Fleming M, Bower TC. Renal nutcracker syndrome: surgical options. Semin Vasc Surg. 2013 Mar;26(1):35-42. doi: 10.1053/j.semvascsurg.2013.04.006. PMID: 23932560. 4. Ananthan K, Onida S, Davies AH. Nutcracker Syndrome: An Update on Current Diagnostic Criteria and Management Guidelines. Eur J Vasc Endovasc Surg. 2017 Jun;53(6):886-894. doi: 10.1016/j.ejvs.2017.02.015. Epub 2017 Mar 27. PMID: 28356209.