Patient: I knew it was a left heavy kidney during pregnancy, but it was just that the fluid in the upper pole pelvis suddenly got bigger at 32 weeks, 2 months, and after checking ultrasound, MR, and diuretic nephrogram, the left kidney function was already below 40 and the fluid was more severe. A doctor suggested to open the window of the cyst, but said there is 50% chance of reflux, and then if it refluxes, we will have to operate again. We don’t want our baby to suffer too much, so we came to ask you, what is the best way to deal with our baby now? Is it necessary to preserve the upper left kidney? Wang Xiang: Hello, I think the diagnosis of left duplicated kidney with ureteral cyst is basically clear. There are two kinds of treatment, conservative and surgical. Conservative treatment is to wait until there is urinary tract infection, or the function of the left upper kidney has obviously decreased, then the left upper kidney will be removed, the disadvantage is that this ureteral cyst may become bigger and bigger, thus compressing the ureteral opening of the left lower kidney, and even the right ureteral opening is affected, causing the corresponding hydronephrosis and affecting the kidney function. There are two types of surgery, one is ureteral cyst opening, the advantage is that the obstruction at the end of the ureter is immediately released and the left upper kidney hydronephrosis will be relieved or even completely cured by this. The disadvantage is that there is a certain chance of vesicoureteral reflux, and mild reflux does not cause adverse effects, but severe reflux may cause urinary tract infection and even decreased function of the left upper kidney. This eventually leads to the need to remove the left upper kidney. Another kind of surgery is to perform ureteral reimplantation, including the left upper kidney ureter alone and the left upper and lower kidney ureter together, etc. The specific type of surgery depends on the specific condition. The advantage is that the obstruction can be removed surgically and anti-reflux surgery can be performed at the same time to reduce the chance of post-operative reflux (note that it is not a guarantee of no reflux). For these children, my personal recommendation at this time is to try to preserve the function of the duplicated suprarenal kidney if it is still functional, by first opening the ureteral cyst, usually by minimally invasive removal of part of the cystic wall under cystoscopy. Next, if severe vesicoureteral reflux occurs, ureteral reimplantation can be performed. The final step is a repeat suprarenal resection. This stepwise treatment process is in line with today’s concept of surgery proceeding gradually from simple to complex surgery and better reflects the value of minimally invasive surgery.