Enlargement of the left testicle usually indicates the presence of a testicular pathology. Generally cause testicular large, the following common etiology: a. Testicular syringomyelia is caused by one side of the scrotum become large, common etiology is mainly due to the testicular syringomyelia cavity fluid increase, caused by the testicular syringomyelia, can be divided into primary syringomyelia or secondary syringomyelia. Regardless of the cause, it will cause the fluid in the sphincter cavity to increase, making the volume of the testicle increase. Second, testicular swelling, due to the swelling of the testicle makes the volume of the testicle increase and the shape becomes irregular. Third, hernia, due to the intestinal contents into the scrotum, making the volume of one side of the scrotum increased also easy to produce the illusion of testicular enlargement. These diseases can be differentially diagnosed by some tests, such as the commonly used urological ultrasound.