<prompt> Varicocele is common on left testis becauseLeft testicular vein drains into IVC which has high pressureLeft testicular vein drains into left renal vein which has high pressureLeft testis is lower situatedCompression of testicular vein by rectum  <response>: Variocele formation has been attributed to one of the three primary factors : Increased venous pressure in left renal vein Collateral venous anastomoses Absent or incompetent valves in the internal spermatic vein. Ref : Bailey Love 23e p1273 