The greatest characteristic of flexible ureteroscope is to operate along the natural lumen of the human body, and complete the operation or inspection of the upper urinary tract, which consists of the upper ureter, renal pelvis and renal calices under non-invasive conditions [10]. About 4 decades ago, the first flexible ureteroscope was created, but at that time it was only possible for doctors to complete the examination. With the development of the medical techniques and services, the current flexible ureteroscope has the excellent operation track, the water inlet and outlet system and active and passive bending flexural system, which has blossomed into the main weapon that play a significant role in surgery for upper urinary tract diseases[11, 12]. According to the study report, the stone removal rate of middle and upper calyx stones with a diameter of less than 2cm is 97%, and that of lower calyx stones is 71.4%[13]. At the moment, the capability of flexible ureteroscope has made significant breakthroughs, and also the surgical indications have further expanded. In the early phase, the double-J stent will be retained for 2–4 weeks before all the flexible ureterorenoscopy performed. The main purpose is to improve the success rate of endoscopy, reduce the difficulty of operation, and avoid acute postoperative complications. However, with the maturity of follow-up technology, the success rate of Phase I operation of flexible ureterorenoscopy is about 85–90%, and the preoperative indwelling of double-J stent is not necessary anymore[6].
Compared with indwelling double-J stent before operation, indwelling double-J stent after operation is much more conventional. The main therapeutic purpose is to prevent infection, ureteral edema and reduce postoperative ureteral stenosis. The retention time is about 2–4 weeks[4, 5]. When the double-J stent has been placed before the operation., is it still necessary for indwelling after the operation? Therefore, the tubeless concept was put forward, that is double-J stents are no longer retained in the ureter after operation[14]. On the contrary, because of the reduction of the time of indwelling double-J stent in the flexible ureterorenoscopy surgery, the total operation time will be reduced. Without the stimulation of double-J stent, the incidence of postoperative hematuria, frequency of urination, urgency and pain of urination were also lower than those in the catheter group. One day after operation, there was no notable difference in the incidence of low back pain, which may be related to mucosal edema and poor urine drainage caused by surgical stimulation. However, with the extension of time, the incidence of lumbago in the tubeless group decreased, and the difference was statistically significant at two weeks.
Postoperative fever or postoperative infection is also an important indicator and complication of flexible ureterorenoscopy. In this study, there was no significant difference in the probability of fever after the preset tube was operated, no matter whether it was tubeless or not. However, for patients who underwent flexible ureterorenoscopy in the first phase, although the double-J stent was also placed in the human body after the operation, the probability of high temperature during 24 hours after the operation was still high, and the difference was statistically significant. It may have a bearing on poor ureteral conditions, polyps around stones, and different degrees of preoperative infection. Research shows that there is a close correlation between postoperative inflammatory factors and postoperative infection and fever[9, 15]. This study shows that the levels of interleukin-6 (IL-6), C-reactive protein (CRP), procalcitonin (PCT) and leukocyte (WBC) after flexible ureterorenoscopy are higher than those before surgery, which may be related to the stimulation of surgery and the high perfusion pressure that causes internal and external toxins to make body secretion in the humoral circulation.
IL-6 is derived from immune cells, and IL-6 rises sharply in the blood within a few hours of bacterial infection.Study report shows that IL-6 is positively correlated with the degree of symptoms in patients with pyemia, which can effectively evaluate the prognosis of patients with IL-6 originates from immune cells, and IL-6 in blood will go up acutely within a few hours because of bacterial infection. Study reports have shown that, the expression of IL-6 is different in patients with pyemia with different outcomes, which can predict the prognosis of patients with pyemia. However, its poor specificity is its biggest shortcoming as a prediction index, which is only 51.66%. IL-6 can reach its highest peak in a short time in patients with pyemia, that is why it has a prognostic value in early diagnosis[16, 17]. CRP is a special protein, which is released by the liver when the human body get injured or infected, which is characterized by super sensitivity and high diagnostic value in infectious diseases. But due to its poor specificity, infection, carcinoma, stress reaction, and so on all lead to its increase[18, 19, 20]. This study shows that the postoperative CRP level of group C is higher than that of group A and group B, indicating that the possibility and degree of trauma and infection will be higher if the operation is carried out directly in one stage without placing the double-J stent before operation, while whether to place double-J stent after operation has little effect, which is go along with the statistical results of venous white blood cells after operation, indicating that there may be a positive correlation between the two.
Generally speaking, the content of procalcitonin PCT in serum is quite poor, but when there is infection happening, its number will rise, and it is positively correlated with the degree of infection[20]. PCT is released by parafollicular cell of thyroid, but it has no hormonal activity. When infection exists, stimulated by interleukin and CRP, it will be synthesized and released into the blood in 3–4 hours. The biggest advantage of PCT is its high specificity. When stress and autoimmunity occur, its value will not change[21, 22]. Therefore, it is of great value in post infection examination indicators. Therefore, the combined use of IL-6, CRP, PCT and WBC can effectively judge the postoperative infection and provide early warning of disease progress alert.