After a child has surgery for hydrocele, there will be several drains in his body. What do all these drains do? One of them is a urinary catheter, which I don’t need to tell you that you have seen it before, to drain the urine out of the bladder. There is also an external renal drain, which is placed at the place where the renal pelvis and ureter are anastomosed, and is used to drain urine. This is because no matter how tightly the surgeon sews, a small amount of urine will leak out of the surgical anastomosis. If the urine around the kidney is not drained out, it may cause infection; and the extravasation of urine may lead to local scar formation and affect the healing effect, which is where the extra-renal drainage tube comes in. On the second or third day after surgery, the extra-renal drainage tube can be removed after the drainage fluid is normal. Another drainage tube is the intrarenal drainage. Nowadays, the international practice is to put an internal stent inside the renal pelvis and ureter. The first is to drain urine. After surgery, there will be more or less edema in the anastomosis of the renal pelvis and ureter, and if a stent tube is not placed to support it, the urine may not flow down. Secondly, some doctors believe that it also has a supportive and dilating effect, but there is no literature to support whether or not it has a dilating effect and prevents stenosis. The internal stent tube is usually left in place for a period of time before it is removed, and the child needs to take the tube home. The tube is usually removed one month after the surgery when the results of the review are normal. During this period, parents should take care of the child and pay attention to routine urine tests to detect signs of infection; in addition, wash the child’s perineum daily. During the period from discharge to extubation, take oral antibiotics as requested by the doctor until after extubation.