Uncracking a Case

Abstract

Nutcracker phenomenon (NCP) refers to compression of the left renal vein (LRV), most frequently between the aorta and the superior mesenteric artery, with impaired blood outflow often accompanied by distention of the distal portion of the vein. The nutcracker syndrome (NCS) is the terminology used when the nutcracker phenomenon is accompanied by a complex of symptoms such as pain (abdominal, flank, and pelvic), hematuria and orthostatic proteinuria. Diagnosis can be made with Doppler ultrasound (DUS), computed tomography (CT), magnetic resonance imaging (MRI), and venography. We describe a case of a young female adult who was identified with NCP by DUS, after a first CT had found no abnormalities. She presented with flank pain and severe hematuria causing a drastic decrease in hemoglobin levels. The management of NCS depends upon the clinical presentation and the severity of the LRV hypertension. The treatment options range from conservative to nephrectomy. Treatment decision should be based on the age of patients, severity of symptoms, and their expected reversibility. This case describes an underreported disorder that presents with non-specific symptoms, demonstrating the difficulties of the diagnostic approach of NCS, as well as the challenges in the appropriate management, given the lack of standardized treatment.

Keywords: Hematuria; left renal vein; nutcracker syndrome.

Figure 1

Doppler ultrasound, transversal scan. (a) Color Doppler image of LRV showing a reduction in anteroposterior (AP) diameter of mesoartic segment and “aliasing” indicating a turbulent flow and an increase in velocity. LRV AP diameter ratio: (b) Hilar segment has an estimated AP diameter of 11.1mm (c) Mesoaortic segment with an estimated AP diameter of 1.8 mm; hilar AP diameter/mesoaortic AP diameter 6.2

Figure 2

Doppler ultrasound. Peak systolic velocity ratios between hilar and mesoaortic segments of LRV. (a) Peak systolic velocity of hilar segment estimated in 19 cm/s; (b) peak systolic velocity of mesoaortic segment estimated in 135 cm/s. Ratio 7.1

Figure 3

Computer tomography; axial plane. (1) SMA; (2) aorta; (3) LRV; there is a left renal vein compression between aorta and superior mesenteric

Figure 4

(a) Transversal scan. Distance between SMA (posterior wall) and aorta (anterior wall) measure approximately 4 mm (normal values are 5-6 mm). (b) Longitudinal scan. Acute angle origin of the SMA from the aorta (normal values reported as 54 degrees +/- 5 degrees