The study of Double-J stent free mode of flexible ureteroscopy and laser lithotripsy: A single center experience

doi:10.21203/rs.3.rs-1626731/v1

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The study of Double-J stent free mode of flexible ureteroscopy and laser lithotripsy: A single center experience

https://doi.org/10.21203/rs.3.rs-1626731/v1

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Purpose

To evaluate the effectiveness and safety of flexible ureteroscopy in the treatment of kidney and upper ureteral calculi under the Double-J stent free mode.

Methods

We retrospectively collected the data of patients who underwent flexible ureteroscopy and laser lithotripsy from February 2018 to September 2021 in our hospital. Cases were divided into three groups according to used of the Double-J stent pre-operation and post-operation, namely, the Postoperative Double-J stent free (Post-F) group with pre-indwelling Double-J stent before operation and non-indwelling Double-J stent after operation, the Preoperative Double-J stent free (Pre-F) group with the Double-J stent not preset before operation and retained after operation, and the Routine group with the Double J stents placed in the ureter before and after operation. The data of all patients, including demographic and stone characteristics, perioperative data, postoperative outcomes and complications, were recorded, evaluated and compared.

Results

554 patients as per prescribed research criteria were included with 101 cases in the Post-F group, 154 cases in the Pre-F group and 299 cases in the Routine group. There was no significant difference in baseline characteristics among the three groups, such as age, body mass index, the cumulative calculi maximum length diameter (CMD), average CT value of stones (p > 0.05). The average operation time among the three groups was also similar which demonstrated no statistical difference. The incidence of grade 0–1 ureteral injury in the Post-F group was higher than the other two groups, and the difference was statistically significant (p < 0.01). There was no significant difference in the operation related complications such as bleeding, renal subcapsular effusion, urosepsis, and ureteral stricture. During the follow-up, the data showed there was a certain proportion of Double-J stent associated complications between the Pre-F group and the Routine group, while no risk of these complications were identified in the Post-F group. At the end of time intervals of one month, three months and six months after operation, the stone clearance rates of the three groups were (88.1% vs 87.7% vs89.6%), (91.5% vs 91.9% vs 93.8%), (93.1% vs 93.0% vs 94.9%) respectively, and the differences did not reach statistical significance. (p > 0.05).

Conclusion

It was a safe, feasible and effective management method to treat renal and upper ureteral calculi by flexible ureteroscopy using Double-J stent free mode. This model could avoid the stent associated complications after operation and is suggested to be widely used in clinic.

flexible ureteroscopy

laser lithotripsy

Double-J stent

stent free

stent associated complications

Urolithiasis is a fairly common disease in urology with a high recurrence rate. It is highly prevalent worldwide and ranks the first in terms of prevalence among hospitalized patients. The incidence rate of nephrolithiasis varies with geographical location, dietary habits, socio-economic and genetic factors, ranging from 7–13% in North America, 5–9% in Europe and 1–5% in Asia [1–2]. The latest survey showed that about 1 in 17 Chinese adults suffered from kidney stones [3]. In recent years, the incidence of urinary calculi in China has increased. A multicenter, large sample study of Chinese people found that demographic and clinical characteristics, including gender, age, BMI, stone anatomic location and geographic region, were significantly correlated with stone composition [4]. At present, minimally invasive techniques are the main surgical treatment for urinary calculi, including retrograde ureteroscopic lithotripsy, percutaneous nephrolithotomy and laparoscopic techniques.

Upper ureteral and kidney stones could also be treated by flexible ureteroscopy and laser lithotripsy, which is particularly favored in cases where the diameter of the stone is less than 2cm.

At present, routine preoperative stenting before flexible ureteroscopy for passive dilation of the ureter is no longer part of the standardized technology. However, since preoperative stenting before flexible ureteroscopy could improve the stone clearance rate and reduce the complication rate, such as ureteric injury [5–8], there are still a large proportion of surgeons adopting this approach before flexible ureteroscopy. Generally speaking, the routine operating procedure for retrograde flexible ureteroscopy and laser lithotripsy consists of three steps. First, a Double-J stent was placed in the ureter of the stone side under cystoscopy before operation. And a fewer days later, the flexible ureteroscopy was performed with a new Double-J stent replacing the previous one simultaneously. Finally, the Double-J stent would be removed by cystoscopy after a certain time interval after operation. However, some patients may experience stent associated complications such as fever, hematuria, pain, frequent urination, urgency, dysuria after the Double-J stent indwelling in the body [9]. All of the above symptoms could cause great disturbance to people’s daily life. If the symptoms are severe, the patients may need to go to the emergency room for treatment or hospitalization. Moreover, transcystoscopic Double-J stent removal will further increase the risk of physical and psychological trauma and economic expenditure. Therefore, it is of clinical significance to explore whether retrograde flexible ureteroscopy laser lithotripsy could avoid Double-J stent indwelling.

Study population

The clinical data of 554 patients with upper ureteral calculi and renal calculi who were treated by retrograde flexible ureteroscopy and holmium laser lithotripsy from February 2018 to September 2021 were retrospectively analyzed in our center. The included patients were those with non-incarcerated upper ureteral calculi or renal calculi who were successfully treated with unilateral, single flexible ureteroscopy and holmium laser lithotripsy and in whose cases, the cumulative calculi maximum length diameter (CMD) measured by CT scan was 10~20mm. The CMD was calculated by measuring the maximum length diameter of the stone according to the CT 3D reconstruction images. The following cases were excluded from this study, including patients with calculi complicated with ipsilateral ureteral stenosis, patients with calculi complicated with pyonephrosis or severe infection, patients with calculi of special types, such as horseshoe kidney, medullary sponge kidney, duplication kidney, transplanted kidney, ectopic kidney, and etc., and patients who had received radiotherapy for abdominal and pelvic tumors. Before operation, all patients received physical examination, urinalysis, urine culture, abdominal CT scan and urinary ultrasonography. The degree of hydronephrosis was judged by the results of ultrasonography. Hydronephrosis was classified into four types, i.e., no hydronephrosis, mild hydronephrosis, moderate hydronephrosis and severe hydronephrosis. All demographic characteristics and preoperative parameters were recorded. The stones characteristics, such as the CMD and CT value of calculi were also recorded. The mean CT values for calculi were calculated from the mean CT values for three different areas of the largest cross-section of the calculi in the CT scan. Complications including surgical complications and stent associated complications were graded retrospectively according to the modified Clavien-Dindo classification [10]. All patients signed informed consent and the study was approved by the Ethics Committee of The Second Affiliated Hospital of Soochow University.

The grouping principle was as follows. The patients were informed of the operation process and whether the Double-J stents were retained in the ureter before and after operation. With due respect of the patients’ willingness, they were divided into three groups. The group of postoperative Double-J stent free (Post-F) group consists of patients with pre indwelling Double-J stent (6Fr) before operation and no Double-J stent after operation. The Routine group consists of patients with the preoperative stenting and postoperative stenting of the Double-J stents (6Fr) both performed. The preoperative Double-J stent free (Pre-F) group consists of patients without preoperative stenting before operation and with indwelling Double-J stent (6Fr) after operation. In the preoperative Double-J stent free group, if it was found that the ureter diameter of the cases was thin and the flexible ureteroscopy delivery sheath could not be successfully inserted, a 6Fr Double-J stent would be retained in the ureter for 2 to 3 weeks, after which the flexible ureteroscopy operation would be performed. And correspondingly, cases of this type were excluded from the preoperative Double-J stent free group and assigned to the postoperative Double-J stent free group and the Routine group with due respect of the patients’ willingness.

Surgical Procedures

All procedures were performed by a deputy chief physician with extensive experience in flexible ureteroscopy. The patients were treated with general anesthesia and pendulum lithotomy position. Under direct vision, a 9.5Fr rigid ureteroscope was inserted from the external urethral orifice to the bladder. If the double J stent was placed preoperatively, it would be removed. By using a guide wire, a rigid ureteroscope was inserted into the ureter to the renal pelvis for routine examination. In the cases with upper ureteral calculi, the calculi would be pushed back to the renal pelvis, while the guide wire would be retained and the rigid ureteroscope would be withdrawn. A flexible ureteroscopy delivery sheath was inserted under the guidance of the wire and a constant pressure perfusion pump was connected or a hand-push syringe may be used for perfusion. The Olympus electronic flexible ureteroscope was inserted into the renal pelvis through the flexible ureteroscopy sheath, and the renal pelvis and all renal calyces were examined for calculi. A 200μm holmium laser fiber was used with laser energy and frequency set as follows (fragmentation mode: 1.2~1.5J/15Hz, pulverization mode: 0.8~1.0J/20~25Hz). The calculi was crushed to a diameter of less than 4mm. During the operation, the larger calculi fragments, especially which deposited in the lower group of renal calyces, would be removed with a stone retrieval basket. In the postoperative Double-J free group, a 5Fr ureteral catheter would be temporarily placed in the ureter at the end of the operation and removed 48-72 hours after the operation. In the preoperative Double-J stent free group and the Routine group, a new 6Fr double J stent would be placed in the ureter at the end of the operation and removed under cystoscope one month after the operation.

Postoperative Procedures and the Follow-up

All patients were followed up for 6 months. Ultrasonography and KUB (or abdominal CT scan) were performed at the end of time intervals of 1, 3 and 6 months after operation. All imaging data were compared with those before operation, and it would be regarded as a complete stone clearance if no stone was found or stone fragments found were no more than 2mm in diameter. The differences of demographic characteristics, preoperative parameters, stone characteristics, operative time, operative complications, double J stent associated complications, and stone free rate among three groups were compared.

Statistical Analysis

Continuous data were summarized using the mean ± SD and compared by one-way ANOVA test. Categorical variables were compared using the chi-square test or Fisher’s exact test. The statistical package for the social science (SPSS Inc, Chicago, Illinois, USA) version 19.0 was used for statistical analysis. P<0.05 was considered as having a statistical significance.

A total of 554 patients (390 males and 164 females) were included according to the inclusion and exclusion criteria. The age of the patients ranged from 23 to 78 years old, with an average age of (48.7 ± 15.9). The body mass index (BMI) was 18.6–28.6, with an average of (24.0 ± 2.0). There were 73 cases of upper ureteral calculi and 481 cases of renal calculi. The cumulative calculi maximum length diameter (CMD) was 10-20mm, with an average of (15.9 ± 2.9) mm. The CT value of calculi ranged from 476 to 1560Hu, and the average value was (1031.8 ± 595.6) Hu.

As per the inclusion and exclusion criteria, 177 patients were included in the preoperative Double-J stent free group, of whom, 23 (13.0%) patients failed to have the flexible ureteroscopy delivery sheath successfully placed during the operation due to the small ureteral diameter. With informed consent of the patients, 6 cases were assigned to the postoperative Double-J stent free group and 17 cases to the Routine group. There was no significant difference in the demographic characteristics and stones characteristics of the three groups, such as age, BMI, hydronephrosis, results of urine culture and asymptomatic bacteriuria, CMD and the mean CT value of calculi. The proportion of female patients in the preoperative Double-J stent free group was significantly higher than that in the other two groups, but there was no significant difference between the groups (P > 0.05) (Table 1).

Table 1

The patients^, demographics and clinical characteristics in three groups
	Cases(n)	Age(years)	Sex (%)	BMI (kg/m2)	Stone location	Degree of hydronephrosis				CMD (mm)	CT value (HU)	Operation time(min)
	Cases(n)	Age(years)	female/male	BMI (kg/m2)	ureter /renal	no	mild	moderate	servere	CMD (mm)	CT value (HU)	Operation time(min)
Post-F	101	47.4±16.4	30/71 (29.7%)	23.6±2.2	20/81	79	12	10	0	16.2 ±2.8	992.2 ±220.5	38.4 ±10.7
Pre-F	154	48.6±16.8	56/98 (36.4%)	23.9±1.9	24/130	125	15	14	0	15.7 ±3.1	1017.1±248.9	38.7 ±11.9
Routine	299	49.2±15.7	78/221 (26.1%)	24.1±2.0	29/270	249	31	18	1	15.9 ±2.9	1000.7±266.1	37.9 ±10.7
P value	—	0.629	0.076	0.563	—	0.510	0.679	0.314	—	0.367	0.162	0.773

The average operation time of postoperative Double-J stent free group, preoperative Double-J stent free group and Routine group were (38.4 ± 10.7) min, (38.7 ± 11.9) min and (37.9 ± 10.7) min respectively. There was no significant difference in operation time among the three groups (P > 0.05). In terms of surgical complications, the incidence of grade 0 and 1 injury of ureteral mucosa in preoperative Double-J stent free group was significantly higher than that in the other two groups (P < 0.01). However, there was no significant difference with regards to the incidence rate of such complications between the other two groups (P > 0.05). Bleeding, ureteral injury (Grade0-1), renal subcapsular effusion and fever were the most common Clavien-Dindo grade I/II complications, which showed no significant difference among the three groups. There was no significant difference in complications such as intraoperative bleeding, subcapsular effusion and postoperative ureteral stenosis among the three groups (P > 0.05). None of the three groups developed urosepsis during or after surgery. In the preoperative Double-J stent free group, one patient was found with hydronephrosis 3 months after operation, and showed progressive aggravation. The membranous stricture of the upper ureter was found by ureteroscopy and cured by balloon dilatation. All the above information was shown in Table 2.

Table 2

Operative and Double-J stent associated complications
Complications	Incidence			P value
Complications	Post-F	Pre-F	Routine	P value
Surgical complications Clavien Dindo I/II Bleeding Ureteral injury (Grade0-1) Renal subcapsular effusion Fever Clavien Dindo III/IV Ureteral stenosis	5 3 2 2 0	8 17 6 11 1	11 8 10 14 0	0.713 0.000 0.694 0.169 —
Stent associated complications Clavien Dindo I/II Hematuria Irritation symptoms of bladder Fever Pain UTI Clavien Dindo III/IV	0 0 0 0 0 0	34 29 11 21 19 0	61 57 14 29 24 0	<0.000 <0.000 0.026 0.001 0.002 —

Regarding Double-J stent associated complications, the common Clavien-Dindo grade I/II complications were hematuria, irritation symptoms of bladder, fever, pain and urinary tract infection (UTI). While there were no stent associated complications in the postoperative Double-J stent free group, these complications frequently occurred in the other two groups. And there was no significant difference between the latter two groups (P > 0.05) (Table 2). 554 (554/554) patients were followed up for 1 month after operation. 504 (504/554) patients were followed up for 3 months after operation. 489 (489/554) patients were followed up for 6 months after operation. The stone free rates of postoperative Double-J stent free group, preoperative Double-J stent free group and Routine group were (88.1% vs 87.7% vs 89.6%), (91.5% vs 91.9% vs 93.8%) and (93.1% vs 93.0% vs 94.9%) respectively. There was no significant difference among them (P > 0.05) (Table 3).

Table 3

Stone free rate in the three groups
	1-month (%)	3-month (%)	6-month (%)
Post-F	88.1 (n = 101)	91.5 (n = 94)	93.1 (n = 87)
Pre-F	87.7 (n = 154)	91.9 (n = 135)	93.0 (n = 128)
Routine	89.6 (n = 299)	93.8 (n = 275)	94.9 (n = 274)
P value	0.613	0.653	0.686

Retrograde flexible ureteroscopy and laser lithotripsy is one of the main minimally invasive methods for the treatment of renal calculi and upper ureteral calculi. The AUA/ES guidelines recommend the provision of flexible endoscopy for the treatment of non-lower pole stones with 20mm or less in diameter [2, 11]. The characteristics of safety, noninvasiveness and easy manipulation of flexible ureteroscopy technique are favored by surgeons and patients. It could even be used for day surgery and outpatient surgery [12–13]. The manipulation and lithotripsy effect of flexible ureteroscopy are generally closely related to the clarity of ureteroscopy imaging, the bendability of head end, the left-right direction adjustability, the size, hardness and location of stones. With the popularization of electronic flexible ureteroscope and the application of disposable electronic flexible ureteroscope [14–16], the clarity of surgical imaging is greatly improved and the learning curve is further shortened, which increases the operation efficiency is better.

Generally speaking, the successful placement of the flexible ureteroscopy delivery sheath is a prerequisite for the success of laser lithotripsy. Usually, 6Fr or 8Fr double J stent was used for preoperative stenting under cystoscopy, and ureteroscopic laser lithotripsy was performed two weeks later. The passive dilation of ureter by double J stent is conducive to the insertion of the flexible ureteroscopy delivery sheath and is able to reduce the incidence of ureteral injury. It also has positive significance for stone removal rate. Although some scholars have reported that compared with the pre indwelling double-J stent group, the stone free rate of non pre indwelling double-J stent for flexible ureteroscopy laser lithotripsy was almost the same, and the overall complication rate was similar, too [17], however, the literature showed that when there was no pre indwelling double J stent, the failure rate of flexible ureteroscopy delivery sheath could reach 9.8%~22.0%[18]. This study showed that the failure rate of flexible ureteroscopy delivery sheath placement in the preoperative double J stent free group was 13.0%, which was close to that reported in the literature. The failure rate of the other two groups was zero. The data further revealed the importance of pre indwelling double J stent for the success of flexible ureteroscopy laser lithotripsy. An interesting phenomenon was found when comparing the gender composition of the clinical data among the three groups. In the preoperative double-J stent free group, the proportion of female patients was higher than that of the other two groups, although no statistical difference was found among the three groups. We hypothesized that gender may be one of the significant factors that influence the success of one-stage flexible ureteroscopy laser lithotripsy, which needed to be verified by large sample investigation.

Urosepsis associated mortality was about 2.5-fold higher in patients with urinary obstruction, which was largely due to urolithiasis [19–20]. Although this complication was rare in this study, all urologist should be alert to it. Using of ureteral access sheath could help to reduce this complication [20–21]. Another advantage of preoperative stenting is that it helps to insert the flexible ureteroscopy sheath to the renal pelvis outlet. Intraoperative irrigation and drainage are more unobstructed when the flexible endoscope sheath is placed in the appropriate position, which reduces the toxin released during lithotripsy and reduces the occurrence of urosepsis. At present, domestic scholars have reached a consensus on indwelling double-J stent in the ureter before operation. They believed that preoperative stenting for more than two weeks was conducive to reducing the complications of ureteral injury and improving the chance of successful operation.

The main purpose of indwelling double-J tube after operation of renal calculi or ureteral calculi is drainage. When the ureteral mucosa was slightly damaged, the role of internal stent was to support and drain, and help to reduce the complications of ureteral stenosis. When the stone load was large, the stent could avoid the acute obstruction caused by stone street. Usually, there may be a certain degree of edema and fluid extravasation in the mucosa of ureteral wall after ureteroscopy. For the sake of safety, most surgeons prefer to indwell double J stent after operation. However, the indwelling of double-J stent often leads to some accompanying symptoms, such as lumbar and abdominal pain, pubic pain, frequent urination, urgency of urination, urination pain, hematuria, sexual life disorder, and even high fever [9]. These accompanying symptoms can seriously hinder the patient's rapid recovery after operation and affect the patient's life quality by preventing them from normal social networking and work. In addition, the removal of double J stent under cystoscopy will bring physical and mental trauma and increase economic expenditure again. Some scholar [22–23] found that short-term postoperative ureteral catheter indwelling (< 6 hours) or even total absence of double J stent was feasible in retrograde ureteroscopy surgery (including flexible ureteroscopy) through phase I and phase II clinical experiments, which helped to improve the quality of life of patients and reduce complications. This study found that in the postoperative Double-J stent free group, the surgical complications did not increase compared with that in the other two groups with similar stone clearance rate and no stent associated complications. From the perspective of the patient’s post operation life quality, it seems to be a better choice not to use ureteral stent after ureteroscopy laser lithotripsy. However, as such, it may fall into the dilemma of acute ureteral obstruction and emergency placement of ureteral stent [24]. In practice, we found that the application of stone retrieval basket to remove large stones during operation and temporary indwelling of ureteral catheter after operation could improve the feasibility and safety of stentless implementation.

In conclusion, the non-indwelling double J stent mode after flexible ureteroscopy laser lithotripsy for renal calculi and upper ureteral calculi was feasible, safe and effective, which can avoid the stent associated complications and improve the patients’ quality of life. In this study, the cases of the postoperative free Double-J stent group were those in which the patients experienced preoperative stenting. Thus, the overall ureteral conditions of these patients were good. Whether patients without preoperative stenting could also selectively adopt this tubeless management mode needs to be further explored. The data of this study were mainly aimed at the postoperative stage without indwelling stent, which was limited by the study sample and the follow-up time. Despite of the certain limitations, it does provide significant references for clinical selection.

Ethics approval and consent to participate

The study protocol was approved by the Ethics Committee of The Second Affiliated Hospital of Soochow University (JD-HG-2022-23). All procedures performed in studies involving human participants were in accordance with the ethical standards of the Ethics Committee of The Second Affiliated Hospital of Soochow University and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The Ethics Committee of The Second Affiliated Hospital of Soochow University waived the requirement for informed consent because of the retrospective design of this study. The informed consent was obtained from all cases and/or their legal guardian(s).

Consent for publication

Not applicable.

Availability of data and materials

The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.

Competing interests

The authors declare that they has no competing interests.

Funding

The present study was supported by the Suzhou Science and Technology Planed Project (grant no. SYS2020139 to Dr. Ming. Xu)

Author contributions

Ming Xu: Data collection, manuscript writing; Xiaoyun Han: Data analysis, manuscript writing; Chuangyang Sun: Project development; Jin Zhu: Data collection; Wei Tao: Data collection; Boxin Xue: Project development. All authors gave final approval of the version to be published.

Acknowledgements

None.

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The study of Double-J stent free mode of flexible ureteroscopy and laser lithotripsy: A single center experience

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