Feasibility and safety of cryoablation on the porcine ureter using a new balloon cryoprobe
Introduction
Endometriosis is the growth of functional endometrial grands or stroma outside the uterine cavity, with the most frequent characteristic of chronic pelvic pain and infertility in females of reproductive age [7]. As one of most common diseases in the female pelvis, endometriosis has an estimated prevalence of 30%–40% in the child-bearing women [33]. The majority of these diseases limited to organs such as the ovaries, uterosacral ligaments, cul-de-sac, pelvic peritoneum, oviducts, and cervix. Genitourinary involvement occurs in 1% to 2% of cases [7]. Among of them, ureteral endometriosis (UE) ranks only second to bladder endometriosis, presenting in 15% of patients with genitourinary disease [14]. According to the depth of ureteral infiltration, UE is divided into two groups: intrinsic UE, infiltrating tissues from the muscularis to the mucosal layers; and extrinsic UE, implicating adventitia and adjacent tissues [36]. Although the incidence was considered rare, untreated UE might result in significant ureteral compression, hydroureter, hydronephrosis, silent loss of renal function, and end-stage renal disease (ESRD) [12].
The main therapy for UE includes hormonotherapy, endoscopic, and/or surgical treatment [23]. The operation procedure should be tailored according to the various factors including patients’ desire to retain reproductive function, severity of symptom, depth and extent of ureteral infiltration, location of UE and the renal status and other factors [5]. The major surgical approaches composed by ureterolysis, ureteral resection with terminoterminal anastomosis, and ureteroneocystostomy [4]. To date, with the improvement of the laparoscopic techniques, conventional open surgery was gradually substituted by laparoscopic surgery since the latter has small incision, rapid recovery and less adhesion [1]. However, owing to the common disruption of the ureteral wall integrity in earlier surgeries, the present surgery options present short and long-term complications, such as urine leakage, stricture at the anastomosis site and a high risk of UE recurrence [13,14]. Thus, new experimental UE treatment methods are emerging to overcome the problem.
Innovation of new technologies offer therapeutic strategies. Cryoablation is a well-characterized and understood ablation technology that has multifarious clinical applications in renal, stomach, prostate, bladder, hepatic tissues and so on [11,15,17,27,37]. Indeed, cryotherapy can be used to treating endometrial diseases through destroying the endometrium and basal layer [29,35]. Elizabeth H and Julie [8,21] performed cryoablation on abdominal wall endometriosis (AWE) patients and obtained that cryoablation was feasible and presented similar effectiveness to surgery alone for local control of AWE. Several animal studies have shown that the application of transurethral cryoablation in bladder is feasible and safe [18,31]. Applying repetitive cryosurgery using a tumoricidal cryosurgical dose on dogs ureters caused permanent ureteral damage [2]. However, to our best knowledge, the cryoablation through transurethral approach in the treatment of UE has not been reported in previous studies.
With the aforementioned in mind, we hypothesized that cryoablation combined with ureteroscope treatment could be used in UE patients, especially in those with intrinsic disease. Since there are no related literature reports previously, we designed the treatment applied in the porcine model as an early period of animal experiment validation. Traditional cryoprobe used in cryoablation has a sharp tip and may injure the ureter wall thus result in perforation. Considering this, we adopted a new balloon cryoprobe designed by Ningbo Senscure Biotechnology Co., LTD (Ningbo, China). Therefore, the aim of this investigation is to clarify the safety and feasibility of the cryoablation, as well as to estimate the ureter histologically for treatment-related effects.
Section snippets
Materials and methods
This study received approval from the Ethic Committee of International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiaotong University.
Results
Pigs from all groups underwent successful cryosurgeries without complications such as perforation, abdominal adhesion, adjacent organ injury, urinomas, stricture, obstruction or hydronephrosis. During surgery, the cryoprobe was placed inside to the ureteral. The iceball was formed inside the ureter and white frost can be seen outside the ureter. The freezing range on serous side of ureteral has a diameter of 2.0 cm after frozen 2min and the volume of iceball inside was about 6 × 6 × 17 mm3 (
Discussion
The prevalence of the endometriosis of the urinary tract increased in recent years, including endometriosis affecting kidney and other organs, especially in bladder and ureter involvement. UE is ectopic lesions involving ureter and results in ureter obstruction, ureteral expansion, hydronephrosis and silent loss of kidney function [4]. UE are less rare than previously thought and may account for 0.3% to 12% among women with endometriosis [7,26], since the lack of overt symptoms and recognition
Conclusion
Our seminal study firstly illustrated the feasibility and safety of combination between cryoablation and ureteroscope applied in the porcine ureter, and provided a new approach to the treatment for UE and other ureter diseases. Using a novel cryotherapy equipment, we have demonstrated that cryoablation might have a wild application field in clinical research.
Declaration of competing interest
All authors declare that they have no competing interests.
Acknowledgments
The study was sponsored by the National Natural Science Foundation of China (No.81172477), the Project of the Science and Technology Commission of Shanghai Municipality (No. 11ZR1440800 and No. 13JC1401303), the Project of Outstanding Subject Leaders of the Shanghai Health System (No. XBR2013097), Shanghai Municipal Key Clinical Specialty (shslczdzk06302), Shanghai Jiao Tong University Medicine-Engineering Fund (No. YG2017MS41) and Fundamental research program funding of International Peace
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