Definite Cutoff Point to Diagnose “Nutcracker Syndrome”: An Ignored Cause of Microscopic Hematuria

Abstract

Background: One of the causes of gross hematuria is nutcracker syndrome or renal vein entrapment. The computerized tomography (CT) scan can demonstrate the precise left renal vein (LRV) compression between the aorta and the superior mesenteric artery. These modalities are usually applied for initial investigations. At present, there is no definite cutoff point to diagnose nutcracker syndrome in patients who present with asymptomatic microscopic hematuria (AMH). Objective: To study whether the nutcracker syndrome might be associated with AMH and to determine the definite cutoff point to diagnose nutcracker syndrome. Materials and Methods: The authors retrospectively reviewed the CT scans of patients diagnosed with AMH and had no abnormal urological findings from standard investigations compared with patients in a control group who had normal urine exams and no urological abnormalities from CT scans. CT scan assessment included the diameter ratio of the LRV at the aortomesenteric angle and the renal hilar, the aortomesenteric distance, and the aortomesenteric angle. Results: Forty-eight patients diagnosed with AMH were included in the present study. The diameter ratio of the LRV at the aortomesenteric angle and the renal hilar in the AMH group was 0.7 compared to 0.9 for the control group (p=0.001). The mean aortomesenteric angle in patients with AMH was 45.9 degrees compared to 54.8 degrees in the control group (p=0.004). The mean aortomesenteric distance in patients with AMH was 1.36 cm compared to 1.56 cm in the control group (p=0.032). Conclusion: These data showed the significant difference in the diameter ratio of the LRV at the aortomesenteric angle and the renal hilar, the aortomesenteric angle, and the aortomesenteric distance between patients with AMH and the normal population. Therefore, the nutcracker syndrome may be associated with AMH. Keywords: Microscopic hematuria, Nutcracker, Left renal vein