<prompt> Varicocele is common on left testis because -Left testicular vein drains into IVC which has high pressureLeft tesicular 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 veinCollateral venous anastomosesAbsent or incompetent valves in the internal spermatic vein. 