The left side of the scrotum becomes the size of an egg, there may be orchitis, epididymitis, varicocele and testicular tumors and other diseases. 1. Orchitis, epididymitis: Inflammatory reaction of testis and epididymis caused by various pathogenic bacteria infection will cause local tissue congestion and edema, which may lead to the appearance of the left scrotum becoming the size of an egg. 2. Varicocele: due to poor local circulation, or congenital developmental factors that cause venous reflux obstruction, it may lead to varicocele causing local scrotal swelling, testicular enlargement may also lead to the left scrotum to become the size of an egg. 3. Testicular tumors: for example, benign tumors and malignant tumors of the testicles may cause the left scrotum to become the size of an egg. To sum up, there may be other reasons for the swelling of the left side of the scrotum, and you need to go to the hospital for diagnosis and treatment.