Duplicate renal and ureter malformation is usually found due to clinical manifestations such as urinary tract infection, urinary incontinence or abdominal pain ect..Clinical treatment methods for complete duplicate kidney and ureter malformation are varied (3), there are two main treatment concepts of duplicate kidney: resection and preservation.
For functional upper kidneys, renal-sparing therapy is advocated. End-to-side ureteral anastomosis and ureterovesical replantation are two surgical methods to preserve the functional upper kidney. Lopes and Hosseini (4, 5) performed ureteral ligation or trophotrophic vascular ligation of the upper kidney for the dysplasia or non-functional upper kidney without upper kidney resection, so as to reduce surgical trauma and make the upper kidney atrophy. However, the long-term therapeutic effect is debatable and lacks confirmation of large sample size. Resection of the upper kidney and ureter is the mainstay of treatment for nonfunctioning or dysplastic upper kidneys. Yin et al. (6) found that the proportion of postoperative complications and reoperation was higher for children with upper renal function < 10% who underwent upper renal sparing surgery compared with those who did not. Renal nuclide examination can be used to determine the upper and lower semi-renal function of repeated kidney, so as to decide whether to perform renal preservation therapy. Our center cannot perform this examination because we do not have nuclear medicine department yet. Based on CT and IVU examination, we observed the thickness of the renal cortex of the upper kidney and the secretion of contrast media to evaluate whether there is any retention value (7). In this study, preoperative imaging examination showed that all the children had the value of preserving upper kidney. There was a statistical difference in the time of the pelvic drainage tube between the two groups. We considered that in the UC group, due to the opening of the bladder and its voluntary contractions, urine leakage may occur at the early stage of anastomosis, resulting in peritoneal inflammation and the increase of exudate.
Ureteral end-to-side anastomosis (UU method) and insertable ureterovesical reimplantation (UC method) are the two main methods of duplicate kidney preservation therapy. Villanueva et al. (8) thought that UU method did not need to open the bladder, and the trauma was smaller than insertable ureterovesical reimplantation method, they compared DaVinci Xi robot and open surgery in the treatment of children with complete duplicate kidney with UU method, found that the postoperative effect and safety were the same, the children recovered quickly and were easier for parents to accept who took DaVinci Xi robot surgery. In our country, DaVinci Xi robot is not yet popular, and the cost is expensive, laparoscopic surgery is still the mainstream. Laparoscopic UU has already been used for the treatment of complete renal duplication (9). Chandrasekharam et al. (10) proposed that ureteral- ureteral reflux (yo-yo reflux) may occur in UU anastomosis, which is more likely to occur in higher location anastomosis of the ureters than in lower anastomosis of the lower ureters, which is likely to lead to the kidney infection and renal scar formation. Gerwinn et al. (11) thought that Yo-Yo reflux was only a theoretical inference, which was not proved. Even if yo-yo reflux occurred, due to peristaltic transport of the ureter, reflux would only exist at the local anastomosis, not necessarily reach the renal pelvis, and would not cause repeated kidney infection and renal scar formation. There is no unified requirement for the diameter of the upper kidney ureter and the incision size of the lower kidney during the end-to-side anastomosis, and there are also controversies, it is generally believed that the ureter diameter > 2cm is not recommended to be treated with UU method, and the incision size of the lower kidney ureter is generally recommended to be about 1cm, otherwise it is easy to cause dysperistalsis of the lower ureter and finally lead to hydronephrosis or other complications(12、13).
Abdelhalim et al (14) reported to use UU method in the treatment of duplicate renal and ureter malformation children with non-functioning upper kidney or upper ureter diameter ≥ 2cm, they had good results, all the children recovered well postoperation. We realize that the longitudinal incision of the lower renal ureter and end-to-side anastomosis of the ureters during laparoscopic UU operation is the difficulty of the operation. During the operation, the upper renal ureter should be anastomosed with the lower renal ureter in an oblique plane, when the lower renal ureter is incised longitudinally, the head or tail of the intended incision position can be suspended from the lateral abdominal wall with an absorbable thread, which could reduce the mobility of the ureter and facilitates the cutting operation. For the upper renal ureter with a diameter of about 1.5cm, we directly performed end-to-side anastomosis, there was no febrile urinary tract infection and ureteral stump syndrome after operation, the children recovered well, we have no experince for the upper renal ureter with a diameter greater than 1.5 cm, and we recommend to perform UU method after trimming the upper renal ureter or insertable ureterovesical reimplantation. Compared with the two methods, there was a statistical difference in surgical time. UC method took shorter time, and the laparoscopic insertable ureterovesical reimplantation (UC method) in our center was simpler than that of UU method. UC method is prone to bladder spasm or leakage, maybe impaired the bladder function, especially in children younger than 1 year, and may appear ureteral opening stenosis or vesicoureteral reflux (15). No cases of vesicoureteral reflux or ureteral opening stenosis were found with UC method in our center. Tang et al. (16) proposed that insertable ureterovesical reimplantation after nipple formation at the distal ureteral opening would reduce the probability of ureteral reflux and anastomotic stenosis, but the laparoscopy technique required was relatively high. The patients studied in our center did not receive papillary ureterovesical replantation, so its efficacy could not be evaluated. When we with UC method for laparoscopic surgery, it should be noted that the opening of the bladder should be close to the ipsilateral junction of the lower renal ureter and bladder. As per the physiological and anatomical structure, female children's upper ureters must be anastomosed with the bladder through under the fallopian tube, otherwise hydronephrosis would develop when she is pregnancy. Both procedures must prevent the emergence of ureteral stump syndrome, hence the distal ureteral stump should be ligated in children with reflux.
Depending on the surgeon's preferences, the double J tube is placed differently in the two surgical approaches. During the procedure, the UC group was normally implanted under the laparoscope, but the UU group was usually placed retrogradely with the cystoscope first. Both double J tubes can also be implanted retrogradely prior to surgery. If UC surgery is performed in the upper renal ureter in a retrograde manner, the upper renal ureter together with the double J tube, can be placed into the bladder. There is a slight chance of misplacement with retrograde ureteral catheterization under cystoscopy. If the UU surgery misplaces the double J catheter into the upper renal ureter, the caudal double J can be transferred via the end-to-side ureteral anastomosis to the lower ureter. Nathan et al. (17) treated duplex kidney by ipsilateral distal ureteroureterostomy (U-U) with or without uresteric stenting, found that stented patients were found to have minor complications (2-UTI and 2-stent displacement). Combined with our surgical experience, the double J tube located in ureter is not increase the difficulty of the operation and not affect the postoperative of the children’s recovery, the operators could be guided the procedure and protect the ureter from impaired, it also can prevent the end-to-side ureteral anastomosis and new ureteral orifice stenosis after surgery. Because double J tube has no anti-reflux effect, when the pressure in the bladder increases, it will cause urine to reflux to the renal pelvis and increase the risk of urinary tract infection, our center recommends that children with double J tube who has normal urine routine, take 1/3 − 1/4 of the therapeutic dose of cephalosporin antibiotics before sleep every day, and no FUTI was found in all patients.