The left testicle is associated with vague pain in the left abdomen, which usually occurs in four diseases: 1) left spermatic varicocele; 2) left epididymal cyst; 3) left epididymitis; 4) left syringomyelia, which are identified by palpation and scrotal ultrasound. Firstly, palpation of left spermatic varicocele will reveal a worm-like vascular mass in the scrotum with obvious tenderness. Secondly, epididymal cysts on the left side may be found in the posterior side of the testicle and epididymis with bulbous tissue that is firm and painful to palpation. In addition, in left epididymitis, there is usually a hard nodule or lump at the end of the epididymis, and in the acute stage of epididymitis, there is also obvious redness and swelling of the scrotum. In addition, in the case of left syringomyelia, the left scrotum is usually swollen and cystic compared to the opposite side, and a flowing fluid will be found when palpated by hand, but the final diagnosis still depends on the scrotal ultrasound. It is recommended that patients immediately go to a regular hospital for scrotal ultrasound, and the four diseases can be clearly identified.