The scrotum of a baby around 50 days old appears big on one side may be caused by testicular syringomyelia, inguinal hernia, scrotitis and other diseases, the main causes are as follows: 1. Testicular syringomyelia: Testicular syringomyelia is relatively common in infants and young children, mainly due to the syringomyelia is not closed, the abdominal cavity of the ascites through the syringomyelia, syringomyelia tube flow to the scrotum, accumulation in the scrotum, the scrotum on one side of the large phenomenon will occur. 2. Inguinal hernia: Inguinal hernia is due to the sheath protrusion is not closed and formed a natural orifice, the intestinal tube will protrude from the orifice out of the abdominal cavity, forming a bulge in the scrotum, resulting in the scrotum of babies around 50 days old appear big on one side. 3. Scrotal inflammation: If one side of the testicle is inflamed, it is usually accompanied by symptoms such as redness, swelling and pain on one side, and the enlarged testicle protrudes from the surface of the body, which is different from the opposite side, and the baby will also be uncomfortable and cry, which requires further treatment in the hospital. Whether it is syringomyelia, inguinal hernia or scrotal inflammation, parents should pay high attention to the baby has discomfort timely medical treatment, to avoid delay in medical treatment.