To report our experience in the diagnosis and surgical treatment of the nutcracker syndrome, which is uncommon, with few larger series published.

We retrospectively analyzed 23 patients with the nutcracker syndrome who presented to our institution from July 1998 to July 2007. A diagnosis of the nutcracker syndrome was suspected from the clinical examination, ultrasound, computed tomography, and magnetic resonance imaging findings. The diagnosis was confirmed by determination of the renocaval gradient using phlebography of the left renal vein (LRV). Because of recurrent gross hematuria and persistent orthostatic proteinuria, 7 patients (4 females and 3 males) underwent LRV transposition. Other patients with mild and tolerable symptoms were treated conservatively. The follow-up range was 14-122 months (mean 42.6).

All 23 patients met the criteria for establishing the diagnosis of the nutcracker syndrome. Ultrasonography, computed tomography, and magnetic resonance imaging revealed entrapment of the LRV between the superior mesenteric artery and aorta. The renocaval pressure gradient was ≥4 mm Hg (normal <1 mm Hg) in all patients. The hematuria and proteinuria disappeared in the 7 patients who underwent LRV transposition, and only 1 patient continued to have pelvic pain. No complications occurred during surgery. The postoperative complications included paralytic ileus in 2 and retroperitoneal hematoma in 1 patient. No improvement or only partial improvement was observed in most patients receiving conservative treatment.

The diagnosis of the nutcracker syndrome is determined from the clinical examination and radiographic findings. In patients who require surgical treatment, LRV transposition is an efficient surgical approach with an acceptable risk of complications. However, in some cases, pelvic pain may persist despite removal of the obstruction of the renal venous backflow.