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 high, 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, and may appear anastomotic stenosis or reflux may occur (15). No cases of vesicoureteral reflux or ureteral opening stenosis were found after UC method. 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 for the operation 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. Female children's upper kidney ureters must still be anastomosed with the bladder through the fallopian tube, as per the physiological and anatomical structure, otherwise hydronephrosis would develop during 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. The two types of double J tubes are inserted into the lower renal ureter before the laparoscopic procedure to guide the procedure and protect the lower renal ureter. 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 repeated retrograde ureteral catheterization under cystoscopy. The caudal double J catheter can be transferred via the lower renal ureter to the bladder by the end-to-side ureteral anastomosis during surgery if the UU surgery misplaces the double J catheter into the upper renal ureter. However, the double J tube in the lower renal ureter can be removed by cystoscope at the end of the UC operation. Indwelling double J tube in UC can prevent possible the end-to-side ureteral anastomosis and ureteral new orifice stenosis in the bladder after surgery. Combined with our surgical experience, the double J tube in the UU operation is located in the lower renal ureter or the cross is located in the upper and lower ureters, or the double J tube indwelling in the UC operation does not increase the difficulty of the operation and does not affect the postoperative of the children’s recovery. 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 for children with indwelling double J tube with normal urine routine, take 1/3 − 1/4 of the therapeutic dose of cephalosporin antibiotics before sleep.