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Ureteric obstruction is the most common complication after renal transplantation, which occurs in 2–7.5% of all transplanted kidneys [1,2]. Traditionally this complication has been managed with open surgery, with considerable morbidity and mortality [3,4]. Currently, minimally invasive endourological techniques, such as percutaneous antegrade or transurethral retrograde endoluminal balloon dilatation and ureterotomy, are being used more frequently for treatment with high success rates and lower complication rates, and thus may offer an appropriate alternative to open surgery [5–23]. Endoscopic management for obstructive uropathy has been used in our institution for the last 12 years. During the initial years, patients were managed mainly with balloon dilatation, but there was recurrence in ≈ 40% of patients, so in recent years patients have been managed increasingly with endoscopic incision . Herein we report our results in eight recent patients with vesico-ureteric anastomosis (VUA) obstruction in their transplanted kidneys, who were managed primarily with percutaneous nephrostomy and endoscopic incision.
PATIENTS AND METHODS
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- PATIENTS AND METHODS
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Between February 2001 and March 2006, six men and two women (mean age 38 years, range 27–57) were diagnosed for VUA obstruction in their transplanted kidneys and transferred to our institution. The diagnosis was based on poor urine output, elevated serum creatinine value, hydronephrosis on ultrasound (US), obstructive uropathy in washout renal scintigraphy, and normal blood flow on Doppler US. Rejection was excluded by renal biopsy when appropriate. All patients had a nephrostomy tube to relieve the obstruction and an antegrade nephrostogram was taken to confirm the diagnosis and to assess the exact nature of the obstruction. The VUA obstruction was partial in seven patients and complete in one. The mean (range) length of obstruction was 0.8 (0.5–1.3) cm. There was early obstruction in five patients (<3 months after transplantation) and late obstruction in three (>3 months after transplantation); the mean (range) interval to obstruction was 6 (2–18) months. The type of transplant was living-related in one and cadaveric in the remaining seven patients. The allograft kidney was placed in the right iliac fossa in seven patients and the left iliac fossa in one. All the allograft ureters were implanted at the ipsilateral bladder wall with an antireflux technique by the transplant surgeons. The immunosuppressive protocol consisted of cyclosporin A (or tacrolimus) and prednisolone and azathioprine (or mycophenolate mofetil). The original nephropathy was mainly glomerulonephritis. The patients’ characteristics are summarized in Table 1.
Table 1. The patients’ characteristics and treatment outcomes
|Patient no.-gender-age, years||Interval to obstruction, months||Length of obstruction, cm||Endoscopic incision approach and instrument||Follow-up|
|1-F-27|| 2||0.5||Antegrade, electrocautery||45 months; asympatomatic, unobstructed, serum creatinine 1.2 mg/dL|
|2-M-31||10||0.8||Antegrade, holmium:YAG laser||33 months; asympatomatic, unobstructed, serum creatinine 1.0 mg/dL|
|3-M-33||18||1.1||Antegrade, holmium:YAG laser||4 months; recurrence after repeated antegrade ureterotomy, open ureteroneocystostomy|
|4-M-57||3||0.7||Retrograde, electrocautery||12 months; asympatomatic, unobstructed, serum creatinine 1.5 mg/dL|
|5-M-49||2||1.3||Antegrade, holmium:YAG laser||6 months; Recurrence after third ureterotomy, open ureteroneocystostomy|
|6-F-35||2||0.7 (complete)||Retrograde, holmium:YAG laser||4 months; Recurrence after repeated ureterotomy, pyeloureteral anastomosis to the native ureter|
|7-M-41||6||0.6||Antegrade, electrocautery||21 months; asympatomatic, unobstructed, serum creatinine 1.1 mg/dL|
|8-M-33||3||0.7||Antegrade, electrocautery||6 months; asympatomatic, unobstructed, serum creatinine 1.3 mg/dL|
The patient was placed in the supine lithotomy position under epidural anaesthesia and one dose of cephalosporin was given during the procedure. First, an antegrade nephrostogram was taken to assess the position of transplanted kidney, the nephrostomy tract and the pelvicalyceal system. If the nephrostomy tract was via an anterior middle or upper calyx access, a 0.1-cm hydrophilic guidewire (Zebra, Boston Scientific, USA) was advanced into the collecting system through the nephrostomy tube. Subsequently the percutanous tract was dilated over the guidewire with a fascial dilator (Cook Urological, USA) from 8 F to 14 F under C-arm fluoroscopic guidance, and a 14 F ‘peel-away’ sheath (Cook Urological) was placed as the percutaneous access port. If the nephrostomy tract was not via an anterior middle or upper calyx access, a puncture of an anterior middle or upper calyx under the guidance of US was used and then the percutaneous tract dilated as described above. Next a semi-rigid 8/9.8 F ureteroscope (Richard Wolf Knittlingen, Germany) was inserted and under vision, a 0.1-cm hydrophilic guidewire was used to assess and pass the VU junction (VUJ). Then retrograde ureteroscopy was performed and the distal end of the guidewire was extracted from the urethra. If the ureterscope could reach the ureteric orifice, a full-thickness incision (until fat tissue was seen) of the obstruction was made at the 12 o’clock (anterior) position (to avoid possible vascular injury) via a retrograde approach with a 2 F electrocautery electrode (Richard Wolf Knittlingen) or holmium:YAG laser (VersaPulse, Coherent, USA). The electrocautery was set at 150 kV for cutting and 60 kV for coagulation, and the holmium:YAG laser was set at a frequency of 8–10 Hz and an energy of 0.8–1.0 J. If the ureterscope could not reach the ureteric orifice, the obstruction was incised via a percutaneous approach at the 6 o’clock (anterior) position. If the VUJ was completely obstructed, the stiff end of the guidewire through the antegrade ureterscope was pushed from the distal end of the ureter towards the bladder. When the obliterated segment was short, the scar could be perforated by the guidewire. Then the VUJ could be bypassed by the guidewire and cut through via a retrograde or percutaneous approach. If the scar could not be perforated by the guidewire, the bladder would be filled with contrast medium and methylene blue, and the distal ureteric segment would be cut towards the bladder (at the 6 o’clock position) under fluoroscopic guidance until the obliterated segment was through. Finally, the VUJ was dilated to a minimum of 5 mm in diameter with a balloon or to 12–14 F with facial dilators to ensure a complete cut. Another guidewire was inserted into the ureter and two 4.8 F JJ stents (Boston Scientific) were placed in the ureter and a 14 F nephrostomy tube was left in situ.
The nephrostomy tube was removed 3–5 days later after an antegrade nephrostogram showed no obstruction. The JJ stents were removed 4–6 weeks later.
During follow-up, serum urea, creatinine, and uric acid level were measured, and urine culture, US examination and wash-out renal scintigraphy were performed every month for the first 6 months, then every 3 months.
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In all, 12 endoureterotomies were performed and all procedures resulted in successful incision of the obstruction. There were no complications during or after the procedures. The retrograde and antegrade endoureterotomies were performed with four procedures in two patients and eight procedures in six patients, respectively. The 2 F electrocautery electrode was used for incision in four procedures in four patients and the holmium:YAG laser used in eight procedures in four patients.
After a mean (range) follow-up of 16 (4–45) months, five of the eight patients (three of five with early vs two of three with late obstruction) had ureteric patency and stable renal function (serum creatinine of <1.3 mg/dL in four patients and 1.5 mg/dL in one patient; normal <1.3 mg/dL in our institution) and no dilation of the pelvicalyceal system, as US and wash-out renal scintigraphy confirmed. In three patients there was a recurrence of obstructive uropathy immediately after JJ stent removal and they underwent repeated endoureterotomy (once in patients no. 3 and no. 6 and twice in patient no. 5). However, the obstruction recurred, and all three patients finally required open surgical correction; ureteroneocystotomies were performed in two patients and recipient-to-donor ureteropyelostomy in one (Table 1).
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Ureteric obstruction is the most common complication in renal transplantation recipients, with most series reporting a rate of 2–7.5%[1,2]. Most obstruction occurs at the site of VUA. A tight submucosal tunnel, oedema, ischaemia and fibrosis are identified as the main causes. Traditional open surgery has been the mainstay of management and several reconstructive techniques have been described, which include reconstruction of the VUA with either a transvesical or extravesical technique, the Boari flap technique, pyelocystostomy or anastomosis of the distal portion of native ureter to the grafted pelvis [1–4]. However, re-operation on the transplanted kidney for ureteric obstruction may be difficult and associated with considerable morbidity and mortality. Kinnaert et al.  reported a 8% mortality rate for patients who underwent open correction. Kashi et al.  compared the outcome of ureteric stent placement and open surgery for the management of ureteric obstruction in renal recipients and reported that there was total graft survival in patients treated with stents, whereas there was only 87% graft survival in those treated with surgery. The development of endourological techniques, such as antegrade or retrograde balloon dilatation and ureterotomy, may resolve ureteric obstruction with lower complication rates and could be regarded as an alternative to open ureteric reconstruction.
Barbaric and Thompson  were the first to document successful balloon dilatation of a transplant ureteric stenosis in 1978. Since then, there have been many reports of successful percutaneous antegrade endoluminal balloon dilatation of transplant ureteric stenosis, with success rates of 43–89%. And many investigators have reported a higher success rate for balloon dilatation in patients with early obstruction (<3 months after transplantation) compared with those with late obstruction (>3 months after transplantation) [6,7]. This difference might be attributed to the ischaemic fibrosis, which is the main reason for the late obstruction whereas early obstruction might be secondary to mechanical causes such as oedema, blood clots, or a restricting submucosal tunnel. In addition, obstruction secondary to ischaemia treated with balloon dilatation had poor long-term results and tended to recur. Bosma et al.  reported that 13 patients underwent dilatation with (nine patients) or with no (four) diathermic incision, only the four patients treated with dilatation had recurrent obstruction, while the nine treated with dilatation and incision had no obstruction recurrence (mean follow-up 58 months, range 27–87). Balloon dilatation can result in multiple tears of the VUJ and result in significant periureteric fibrosis, which may be contributing factors for recurrence. To avoid the disadvantages of balloon dilatation, some authors recommended incision of the obstruction (endoureterotomy) or prolonged ureteric stenting with no balloon dilatation. Conrad et al.  reported that 82% of ureters incised with a cold-knife had long-term success. Erturk et al.  treated distal obstruction of the transplanted ureter with AcuciseTM (Applied Medical, Irvine, CA, USA) endoureterotomy. Although three of seven patients had graft failure, all the ureters remained patent. Pappas et al.  managed obstructive uropathy in transplanted kidneys with percutaneous nephrostomy and prolonged ureteric stenting. After prolonged ureteric stenting (mean duration 15 months), there was no recurrence of obstruction in six of eight patients. The outcomes of published reports (with more than five patients) on endoscopic management for ureteric obstruction in transplanted kidneys are summarized in Table 2[6,7,9–24]. The total long-term success rate was 68%. In the present series, the long-term success rate was five of eight patients, which is similar to published data (Table 2), and similar to the results for general patients with ureteric obstruction treated with endoscopic techniques . There was no difference in the success rate between early (<3 months after transplantation) and late obstruction (>3 months). However, patients with a long obstruction (>1.0 cm) and complete obstruction, tended to recur. In the present series, in the three patients in which obstruction recurred, the obstructions were long (>1 cm) in two and it was complete in one.
Table 2. Contemporary results and endoscopic methods used for managing ureteric obstruction in transplanted kidneys
|Series||No. of patients||Success rate, n/N (%)||Method of treatment||Follow-up, months|
|Oosterhof et al. || 6|| 4/6||Percutaneous antegrade dilatation with semirigid fascial dilators||Mean 15|
|Farah et al. || 17|| 9/17 (53)||Percutaneous balloon dilatation||Mean 17.8|
|Benoit et al. || 17|| 12/17 (71)||Percutaneous antegrade endoluminal dilatation||Not mentioned|
|Lojanapiwat et al. || 21|| 12/21 (57)||Percutaneous dilatation and stenting||Up to 56|
|Bosma et al. || 13|| 9/13||Balloon dilatation with or without diathermic incision||Mean 58|
|Fontaine et al. || 44|| 31/44 (70)||Balloon dilatation||2.25–24|
|Bhagat et al. || 41|| 23/41 (56)||Percutaneous ureteral stent or balloon dilatation||2–68|
|Conrad et al. || 18|| 7/18 (39)||Balloon dilatation||13|
|Yong et al. || 9|| 8/9||Antegrade balloon dilatation and temporary internal stenting||Mean 22|
|Erturk et al. || 7|| 7/7||Acucise endoureterotomy||Mean 13|
|Pappas et al. || 12|| 9/12||Percutaneous nephrostomy and prolonged ureteric stent||Mean 9.7|
|Kristo et al. || 9|| 9/9||Antegrade balloon dilatation and 3 with holmium:YAG laser endoureterotomy||Mean 24|
|Bhayani et al. || 8|| 6/8||Acucise endoureterotomy or balloon dilatation||Mean 21|
|Katz et al. || 14|| 13/14||Transurethral incision||8|
|Schwartz et al. || 6|| 5/6||Acucise endoureterotomy||Mean 27|
|Bachar et al. || 21|| 13/21 (62)||Percutaneous balloon dilatation||Mean 20.5|
|Bromwich et al. || 7|| 3/7||Balloon dilatation||Mean 17|
|Aytekin et al. || 19|| 17/19 (89)||Percutenaous nephrostomy and balloon dilatation or Acucise endoureterotomy||6–66|
|Total||290||197/290 (68)|| || |
In practice we prefer incising the obstruction with electrocautery or holmium:YAG laser, and then following with dilatation using balloon dilatation or fascial dilators, which can render a clean, complete linear cut of the VUJ, good haemostasis and minimally fibrosis reaction. In addition, this method is cheaper than Acucise and can be performed as an outpatient procedure. When both eletrocautery and holmium:YAG laser are available for ‘cutting’, some prefer the holmium:YAG laser, as it has better coagulative and precise incisional properties. However, in our previous study, we compared the healing outcome of the PUJ in mini-pigs after endoscopic incision by electrocautery (cutting 150 kV, coagulation 60 kV) and holmium:YAG laser (10 Hz, 1.2 J) using the ureter healing score standard of Kerbl et al., and there was no statistical difference in histological healing between them . We also compared the clinical outcomes of endopyelotomy for patients with PUJ obstruction cutting with electrocautery and holmium:YAG laser. Although cutting with the holmium:YAG laser was more convenient than electrocautery, the success rate of the two instruments was not statistically distinguishable . Because the medical fee for the holmium:YAG laser is more expensive than that of electrocautery in China, we only select the holmium:YAG laser for cutting when the obstruction is >1.0 cm or is complete. The site of the endoscopic incision is normally at the 12 o’clock position . We agree that a retrograde incision can be made at the 12 o’clock position to avoid possible vessel injury. However, if the incision is made via an antegrade approach, we prefer making the incision at the 6 o’clock position, as the allograft ureters were always implanted at the ipsilateral anterior or posterior bladder wall by the transplant surgeons, thus cutting at the 6 o’clock position was the most direct route to the bladder.
Stenting the ureter after endoureterotomy is a routine practice but the optimal stent size remains unknown. Some authors advocate using a stent calibre as large as possible to act as a mould around which the ureter is endoscopically incised and the most used stents are the tapered endoureterotomy stents (7/14 F). In clinical practice we placed two 4.8 F JJ stents in the ureter instead. On the one hand the endoureterotomy stent is unavailable in our institution, on the other hand we deem that the two 4.8 F JJ stents could provide effective flow of urine and be a good scaffolding around which the ureter could rebuild itself. Also, this type of stent is soft, causing little bladder irritation. The optimal stent duration is another enigma. As most authors recommended, we placed the stents for 4–6 weeks. We do not favour prolonged ureteric stenting, because it increases the risk of urosepsis, which can be fatal to renal recipients with immunosuppressants, and it decreases the intraluminal flow and can be a relative obstructive factor to urine drainage. In addition, encrustation, pain, haematuria and reflux are inevitable complications of prolonged ureteric stenting; the stent can also migrate and even fragment.
For patients in which obstruction recurs, some authors have reported successful endoscopic re-treatment. But in the present series, obstruction recurred in three patients after the initial endoureterotomy procedure and all failed repeated procedures and had to undergo open surgical correction. In our experience of endoscopic management for general patients with ureteric obstruction, patients who fail to respond to the initial endoscopic procedure tend to recur to repeated endoscopic procedures. Thus, when an initial endoscopic therapy fails, we think that an open surgical reconstruction should be considered. Recently Bromwich et al.  reported that the success rate of repeated multiple balloon dilatations for ureteric strictures in renal allografts was only 25%, they also recommended that definitive surgical management should be considered if a first dilatation fails.
In conclusion, percutenaous nephrostomy and endoscopic incision is a safe and effective method for treating obstruction of VUA in transplanted kidney, and it can be the initial therapy used for ureteric obstruction in transplanted kidneys; however, open surgical reconstruction should be considered if a first endoscopic-incision procedure fails.