Table 4 Main clinical consequences of renal vein variants.

CLRV

• Risk of injury during surgery^31,110. Sometimes, the posterior limb is not acknowledged before surgery and the renal vein seems to be normally looking, case in which the surgeon might injure the posterior limb²⁷.

• Changes needed of the standard surgery protocol for renal transplantation, aneurysm resection³¹

• See also RLRV

RLRV

• It may have a high number of lumbar retroperitoneal tributaries, forming complex retroaortic systems, which can be easily injured during surgical dissection²⁷

• Changes needed of the standard surgery protocol for renal transplantation, aneurysm resection³¹

• May have a sharp descending trajectory, joining the left common iliac vein, altering the surgical protocol²⁸

• The presence of a RLRV or CLRV is associated with a decrease of the infrarenal segment of the IVC, which could be an important consideration when placing a IVC filter, some of them being too long for the short infrarenal IVC segment³⁰

• RLRV has been associated with renal ectopy. For example, Macchi described a case of RLRV that was draining toward the IVS through two vessels which diverged into an acute angle and emptied independently into the IVC, forming a retroaortic juxtacaval aortic ring⁵.

• Can be a correctable cause for varicocele. Arslan found a significant association between varicocele and RLRV²

• Pelvic congestion syndrome (dysmenorrhea, lower abdominal pain, varices – vulvar, gluteal, thigh)³

• Left gonadal reflux in men (lower limb varices, varicocele)³

• Can mimic a cancer³⁴

• Fistula between the aorta and RLRV has been reported^111,112

• Can cause Nutcracker syndrome/phenomenon. There are two main forms of the Nutracker phenomenon: anterior NP, in which the LRV is caught in the fork between the abdominal aorta and the superior mesenteric artery, and posterior NP, in which there is a decreased space between the aorta and the spine, compressing the RLRV¹¹³; this leads to hematuria due to increased pressure in the LRV, causing congestion of the left kidney and the presence of venous communications⁹.

• Can lead to renal vein hypertension⁷² with hematuria. For example, Gibo and Onitsuka described the case of a 13 years old girl who accused macrohematuria and low back pain; during the clinical investigation, it was found to have a RLRV, with compression of the vein between the aorta and the spine, causing an increased pressure gradient between the LRV and the IVC (mean of 6.8 mm Hg)⁴ (a value above 3 being indicative for renal vein hypertension).

• Can lead to hematuria. For example, Karaman showed that compression of the RLRV is significantly associated with hematuria (out of 16 patients with compression of the RLRV, 15 patients were in the urological group); moreover, the urologic symptomatology was more frequent in RLRV types II and IV⁹.

• Can cause left flank⁵² or low-back pain⁴

• Can cause ureteropelvic junction obstruction⁵²

• Renin sampling from the renal vein³; a false lower renin level can be obtained with the catheter tip in the proximal portion of the left renal vein, due to additional supply from the left gonadal, second lumbar and hemiazygous veins¹¹⁴

• Increase the intrarenal venous impedance index¹⁰³, potentially causing nephrolithiasis or renal cysts³⁹

MRVs

• Injury during surgery³¹

• Changes needed of the standard surgery protocol for renal transplantation, aneurysm resection³¹