LAUSR

Nutcracker syndrome (NCS) refers to compression of the left renal vein (LRV) and involves symptoms such as hematuria and low back pain. There are two variants of NCS: anterior (ANCS) and posterior (PNCS). In ANCS, the LRV is compressed between the aorta and the superior mesenteric artery, whereas in PNCS, the LRV has a retroaortic course and is compressed between the aorta and vertebral column. Posterior NCS is the rarer of the two variants, with a prevalence of 0.77–1.56% (1,2). Ultrasound is an important tool for examining blood flow in the LRV as well as the spectrum, with high sensitivity (69–90%) and specificity (89–100%) (3). However, few studies have focused on the ultrasound features of PNCS. In this paper, we describe the clinical and ultrasound characteristics of eight cases of PNCS that could help to establish an accurate diagnosis. We also followed up these cases in an effort to gain an understanding of the features and prognosis of PNCS.