Yang-Monti ileal ureter-bladder anastomosis or Yang-Monti ileal ureter-ureteral anastomosis for the treatment of ureteral stenosis: What is better?

Background: To establish an animal model of the of anastomosis and ureteral-ureteral anastomosis using the Yang-Monti technique, and compare the advantages and disadvantages. Methods: 14 minipigs were randomly divided into two groups. Group A received the left Yang-Monti ileal ureter-ureteral anastomosis ; group B received the left Yang-Monti ileal ureter-bladder anastomosis. The length of the incision and the operation time of the two groups were compared. Changes in serum creatinine and urea nitrogen were observed. IVU,cystography,Urinary culture examination and histological examination were performed. Results: the remaining 11 miniature pigs had no urinary fistula or intestinal fistula.The operation time and incision length of group A were longer than group B. All minipigs had normal renal function before and after surgery. There was no stenosis obstruction in the venous pyelography. The narrowest diameter of group A was larger than that of group B; no contrast agent was returned to the upper urinary tract in the two groups. Postoperative urine culture examinations were colonized with Escherichia coli. the obstruction and stenosis were found in group A; the ileal ureteral diameter of group A was larger than that of group B. Histological examination showed that the transitional epithelium and columnar epithelial mucosa in group A were not close together; the intestinal villi are slightly atrophied and shortened. Conclusions: Compared with the Yang-Monti ileal ureteral anastomosis, the Yang-Monti ileal ureter-bladder anastomosis is simpler, more reliable, and less complication.

animal welfare on the basis of scientific principles: or the improvement of experimental procedures and improvement of experimental techniques to avoid or alleviate the pain and nervousness of animals that are not related to the purpose of the experiment. scientific method.

2.
Surgical procedures and postoperative treatment 2.1 surgical steps Group A surgical steps: (1) Preparation before surgery: Animals were fasted for 24 hours and water for 12 hours before surgery. iodophor, and the intestine was anastomosed with 5-0 non-absorbable suture. The whole layer was sutured first, and the muscle layer was sutured to restore the continuity of the intestine and close the mesangial hole.
(7) Cutting of the intestine: The cutting method of the intestine is referred to [17] ( Fig. 1). The intestine segments were thoroughly cleaned and disinfected with saline and 2.5% iodophor, and the intestine segments were cut into three segments, each of which was 2 cm in length and with independent and intact mesenteric vessels ( Fig. 2a). The cross section of the intestine was taken from the mesentery at 6 o'clock. The three segments of the intestine were cut longitudinally at 9, 12, and 3, respectively, to form a three-section rectangular intestine (length 4-6 cm, width 1.5 cm) (Fig. 2b) ). The adjacent intestine pieces were sequentially sutured with an antibacterial micro-chord line (4-0) to form a rectangular intestine piece having a length of about 12-18 cm and a width of 2 cm (Fig. 2c). The intestine piece was wrapped around a 30 cm long F12 silica ureteral stent tube, and the intestine piece was sutured longitudinally with a 5-0 absorbable suture (Johnson) to form a long tubular structure to form a ureter replacement segment (Fig. 2d).
(8) Reconstruction of the ureter and ureter stump anastomosis: one end of the ureteral stent has been placed in the renal pelvis and the other end of the ureteral stent has been inserted into the bladder through the naive ureteral stump, the top of the bladder is cut open, the stent tube is pulled out and the bladder is made, suture the bladder incision as a stent and drainage. The reconstructed ureteral upper end was anastomosed to the ureteral stump with a 5-0 absorbable suture. The lower end was anastomosed to the remaining ureteral lower end. The anastomosis was performed with a full-thickness suture and sutured for approximately 6-8 needles (Fig. 2e). (9) The distal end of the ureteral stent tube was placed under the skin of the left lower abdomen, and the incision was closed layer by layer.
Group B surgical steps: (1) -(7), (9) same surgical procedure as group A. The contralateral kidney and ureter were removed in the two groups one week after surgery.

post-operative treatment:
Fasting for 24 hours after operation, liquid diet on the second day after surgery, normal feeding after 3-5 days, daily intramuscular injection of penicillin (1.5ml/kg), and metronidazole injection 50ml/day for total 5 days. The ureteral stent tube was indwelled for 4 weeks and then surgically removed and removed subcutaneously.When collecting tissues and organs for examination, abdominal anesthesia was performed first. After the completion of the collection, chemical euthanasia was used to terminate the life of the animals from intravenous high-dose anesthetics.

3.
Observation indicators and data collection: All the experimental animals in the two groups were examined for the following items after surgery: (1) Operation time and length of surgical incision: The operation time and length of the surgical incision were compared between the two groups.
(2) Determination of blood and kidney function: Blood samples were taken to detect changes in serum creatinine and urea nitrogen before surgery, and 2 weeks, 6 weeks and 12 weeks after surgery.
(4) Urine bacteriological determination: urine was collected from the bladder in the urine at 12 months after surgery to see if there was a urinary tract infection.

Statistical analysis:
Animal grouping was designed according to the principles of equilibrium, control and repetition. All measurement data were expressed as mean ± standard deviation. The t test was used for comparison between the two groups. The test level: p was 0.05, and the difference was statistically significant at p < 0.05.
Statistical analysis was performed using the SPSS 24.O software package.
Results ureter, surrounded by fibrous tissue and adipose tissue. After the incision, the mucosa of the intestine and ureteral anastomosis is seen after the incision.
Continuous, intestinal mucosa atrophy on the surface of the intestine and no hydronephrosis. The ileal ureteral diameter was compared between the two groups (p = 0.02), the diameter of group A is larger than that of group B (Table 1-3).
Histological examination showed that in group A, the transitional epithelium of the upper and lower ends of the ureter of the two pigs was not close to the columnar epithelium, and there was granulation tissue hyperplasia. The two pigs with obstruction were found to have fibrous tissue and smooth muscle tissue hyperplasia and support stenosis at the anastomosis.

Discussion
In this experiment, we established an animal model of ileal ureter-bladder anastomosis and ileal ureter-ureteral anastomosis using the Yang-Monti technique.
There were no significant differences in serum creatinine and urea nitrogen between the two groups at 2 weeks, 6 weeks and 12 weeks after surgery. Comparing with before surgery, renal function is stable and there is no renal dysfunction and failure after surgery. We believe that serum creatinine and urea nitrogen are stable at normal levels after surgery and compared with those before surgery. No renal dysfunction was found. We successfully established the Yang-Monti ileal ureter animal model.
In our experiment, the average operation time and length of the surgical incision in group A were longer than those in group B, indicating that the group A intestine ureter and the ureteral anastomosis need to retain and fully free the lower ureter, the lower ureter is deeper, the intraoperative anastomosis operation space is relatively small, the anastomotic speed is slow, so the length of the surgical incision and surgery required The time is correspondingly prolonged; the intestine ureter of the group B is directly anastomosed to the bladder, and the lower segment of the ureter is not required. The bladder of the minipig is more easily recognized under filling conditions, and the top wall, the two side walls and the front and rear walls of the bladder are not connected to the surrounding pelvic wall. The relative position of the bladder in the pelvic cavity is not fixed, the activity is large, and it is easier to find than the lower part of the ureter. It is easier to re-integrate the ureter and the left side of the bladder during operation, and the operation space is large. This may be the length of the surgical incision and operation time required in group B were shorter than that of group A.
The most common recent complication of ileal ureteral surgery is urinary tract infection, which is related to bladder ileal reflux, intestinal mucus secretion, etc., and it is difficult to control and recurrent, eventually leading to hydronephrosis or multiple renal cortex abscess, pyelonephritis [7,18,19] . Urine culture tests confirmed mostly E. coli infection, followed by Klebsiella pneumoniae [12] . Yao Zhengzi et al. cases of urinary tract infections in the clinic, and the symptoms disappear after treatment with antibiotics. Therefore, they believe that changes in urine do not need to be considered excessively in the presence of urinary tract infections, antibiotic treatment is needed only when symptoms of acute infection occur [20] . In this experiment, urine cultures suggest that Escherichia coli colonization was consistent with the literature reports. Escherichia coli is a pathogenic pathogen of the intestine, may be colonized with the intestine to the urinary tract during surgery and no antibiotic treatment because of asymptomatic Bacterial urinary.
There are two ways of ileal ureteral surgery and bladder anastomosis: non-antireflux and anti-reflux. Non-anti-reflux is an ileal that replaces the ureter directly after the bladder. The operation is relatively simple and convenient. The operation time is short and the incision is small. However, there may be a postoperative intravesical urine reflux to the replacement ureter or ipsilateral kidney, resulting in postoperative Intestinal dilatation, ascending infection, pyelonephritis, hydronephrosis, impaired renal function [13] . Anti-reflux anastomosis is beneficial to reduce the above complications. In our experiment, no stenosis obstruction was observed in the two groups. The narrowest diameter of the intestine ureter was compared between the two groups. The diameter of the intestine ureteral tube was larger in group A than in group B.
We believe that intraoperative measurement of ureteral diameter, although according to the measured value of the selection and cutting of the ileum, the reconstructed intestinal ureteral diameter is still thicker than the normal ureteral tube diameter. Group A need to cut the ureter longitudinally after anastomosis. In the group A, the ureter should be longitudinally dissected after the anastomosis, and then the intestine ureter and the lower ureter should be anastomosed. The anastomosis is relatively small, the ileum is more stretched than the ureter, and the urine flows through the relatively small lower ureter after passing through the large intestine ureter. The urine flow rate is slowed down, the stagnation time is long, and the urine stays in the intestine. In the ureter, it is bound to have an expansion effect on the intestine ureter, and the indwelling endoscopic tube will also have an expansion effect after operation; while the intestine ureter of the group B is directly matched with the bladder, the anastomosis is wider than the A group, and the angiography of the venous pyelography is performed. The agent quickly enters the bladder through the intestine ureter and is not easy to reside. This may be the reason why the intestinal ureteral diameter of group B is slightly thinner than that of group A.
Since the Yang-Monti ileal ureter is directly matched with the bladder, the anastomosis is large, is it highly prone to reflux? In our experiment, no contrast agent was returned to the upper urinary tract in the two groups. The group A intestine ureter and the lower ureter were anastomosed, and the anti-reflux mechanism between the ureter and the bladder was retained, therefore there was no reflux. In group B, although the intestine ureter directly matched the bladder, the anastomosis was large and directly opened to the bladder, no reflux occurred.
We believe that no reflux in group B may be related to intestinal ureteral diameter, because the intestinal ureteral diameter is close to the normal ureter, moreover, the intestine ureter has good elasticity and long length. The ileum still retains its peristaltic function after replacing the ureter, which is beneficial to combat intravesical pressure. This requires further measurement of intestinal ureter, renal pelvis and intravesical pressure to confirm. Secondly, the minipig has a short urethra, good bladder elasticity, and rapid urine emptying, so there is no reflux.
Therefore, it is of little significance to establish an anti-reflux mechanism in the Yang-Monti ileal ureter.
The intestinal epithelium is a single-layer columnar epithelium, the urinary tract is a transitional epithelium, and the intestinal tract examination after ileal ureter replacement shows that all the anastomotic regions have unobstructed lumens, no epithelial proliferative changes in the junctional zone, and less than 1 adjacent to the junctional zone. A very short distance of centimeters, migration epithelial metaplasia cover [21] . In the animal experiment of ileal ureter with YM method in rabbits, histological sections at 12 weeks after operation showed that there were stratified transitional epithelial cells crawling to the intestinal mucosa at the anastomosis, covering part of the intestinal mucosa, and the intestinal mucosa on the inner surface of the ureter was obviously atrophied [22] . Minipigs were used for ileal ureteral surgery. The columnar epithelium was still visible in the middle ileum after 3 years of operation. The villi were atrophied and some of the villi became shorter and wider [23] . In our experiment, the histological examination of the intestine and ureter was consistent with the report in the literature. After the ileum was replaced by the ureter, its environment changed, and its histological characteristics also changed. This is the performance of the ileum to adapt to the In group A, the distal end of the inferior ureter and the lower end of the ureter were completely obstructed and stenotic. The upper ureter and ureter and renal hydronephrosis were obvious. In group B, one pig was found to have hydronephrosis and the intestine ureter was slightly dilated. Back to the anastomosis is smooth.
Histological examination showed that group A found hyperplasia of fibrous tissue and smooth muscle tissue at the anastomosis, supporting stenosis or obstruction.
We believe that group A intestinal ureter and ureteral anastomosis, inevitably free of the lower ureter, the ureteral wall is thin, may lead to poor blood supply in the lower ureter, although the ileal ureteral blood supply is good, the effective blood supply between the ureter and the ureter may be poor after the anastomosis, and more fibrosis or scarring occurs after surgery. Therefore, the incidence of stenosis or obstruction and hydronephrosis is higher than that of group B. Group B ureter and bladder directly match the bladder blood supply. Rich, with the intestine ureteral anastomosis at the blood supply, postoperative stenosis or obstruction may not be easy. Although no evidence of hydronephrosis and regurgitation was found in intravenous pyelography and cystography, it was found that there was a porcine -Consent to publish: The manuscript has been approved by all authors for publication.
-Availability of data and materials: Not applicable.
-Competing interests: The authors declare that they have no competing interests.
-Funding: The design and data collection of this study were supported by the Guizhou Province Science and Technology Fund.       NC3Rs ARRIVE Guidelines Checklist (fillable).pdf