1. Figure 1 Anatomy of the venous drainage from the testes
Figure 1 | Anatomy of the venous drainage from the testes. Varicoceles arise when blood flows backwards into the internal spermatic vein resulting in vascular dilation of the veins in the pampiniform plexus. Reflux of blood is thought to be caused by congenital insufficient or absent venous valves and is most often found on the left side as the hydrostatic pressure is higher on this side owing to the perpendicular drainage of the left internal spermatic vein into the left renal vein. The hydrostatic pressure on the left side can increase even further as the superior mesenteric artery crosses the left renal vein and exerts additional pressure often termed 'the nutcracker effect'.
Jensen, C. F. S. et al. (2017) Varicocele and male infertility
Nat. Rev. Urol. doi: /nrurol