Radiotherapy therapy (RT) is an important measure for gynecological tumors, which may subsequently lead to complications such as tissue fibrosis. Ureteral stricture (US) related to gynecological surgery combined with RT is particularly prominent. Some researchers have indicated that the possibility of US is related to whether surgery and the total radiation dose received [11, 12]. Tissue fibrotic response of RT has the characteristic of time-progressive, so that the US usually occurs and develops years after treatments [13]. Some studies suggest that the incidence of US after RT for cervical cancer is about 1.8 -10.3% [14, 15]. As is reported, the risk in the US has increased by 0.15% per year in the 25 years after RT for cervical cancer [16]. In our case, the mean interval time of US needing treatment was 5.35 ± 4.14 years, as similar as other researchers reported was 782.5 (37-2323) days [15].
Memokath stents are of benefit in the treatment of gynecological malignancy patients with a ureteral stricture who need radiation as an aid in end-of-life care. According to our experience, Memokath have excellent performce in situ result from its tight spiral structure with a shaft diameter of 10.5 F. Furthermore, compared to DJ stent, there is no need for frequent replacement and without related LUTS symptom, which has brought improvement of quality of life [17, 18].
The treatment protocol mainly depends on the location and length of the US, prognosis, comorbidities, and even the intention of the patient. The treatment regimen included active monitoring, reconstructive surgery, nephrostomy, and double-J (DJ) stent [19,20,21]. For the radioactive US, it often has the character of long length, heavy degree of stenosis, and a history of abdominal surgery. Memokath has the merits of strong pressure resistance, diversified models, and easy of placement and removement, so it is suitable that Memokath stent to treat US after RT [4, 6, 22].
According to our study, all stents were successively inserted. The average operation time and the average operative hospital stay is similar to another research [6]. Memokath stent can be inserted by retrograde and/or anterograde, mostly through retrograde path [23]. However, there were 22% cases underwent retro-anterograde combination path in our study. Combined with relevant literature and our experience, it is believed that retrograde-anterograde way of stent implantation has some advantages: infection control, short drainage path, precise stenosis assessment for impaired renal [24].
As the ureter is not as straight as radiography showed, how to measure length of US precisely? According our experience, the measuring catheter can be used to precisely measure the length of narrow segment (between the two arrows in Fig. 1B), which is helpful to select appropriate length size and models.
Stent complications include migration, stent occlusion and encrustation, stent-related UTI, etc. Our results suggested that the timely patency rate of postoperative stents was 92.86%, similarly with those reported [4]. Early complications included fever and renal colic, with an incidence of about 7.14%, while symptoms relief after conservative treatment. Related study reported that the effectiveness of Memokath is 40 -75% [25], with the incidence of stent encrustation is < 10%, stent migration < 20%, and stent-related UTI are approximately 7% [26]. In our study, the long-term stent patency was 81.48%, and the late complications included refractory UTI in three case (11.11%), one case of stent migration (3.70%), and another one of stent intolerance (3.70%). In the other two patients, Memokath stents were removed and treated with nephrostomy or D-J tube. According to some literature, the median Memokath stents lifespan was 12-14.5 months in previous study [27].
Nowadays, there is few studies about Memokath stent for change of GFR and hydronephrosis. In our study, the volume of postoperative hydronephrosis was significantly reduced compared with that before surgery, both of them were statistically significant; creatinine levels have an improvement, but no statistical difference. It indicates that Memokath stent can effectively improve the ureteral obstruction and renal function.
Our study had several limitations. First of all, we did not further compare the efficacy and safety of other treatments with Memokath stents. What’s more, the retrospective nature and the relatively small patient population of this study have their own inherent limitations. Last but not least, many patients received radiation therapy at other institutions, it was not possible to trace and record the specific radiotherapy doses. Further studies and multi-center studies are required to evaluate the long-term outcomes of Memokath stent for radioactive US. However, our study fills the gap of the Memokath stents in ureteral stenosis after radiotherapy for gynecological tumors.
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