Open ureteroplasty with buccal mucosa graft for long proximal strictures: A good option for a rare problem

While short strictures and even long strictures in the distal or mid-section of the ureter can easily be repaired by end-to-end anastomosis or simple re-implantation as well as standard procedures, such as psoas bladder hitch and/or Boari-flap, reconstructions of long proximal ureter remain rare and challenging [1].

Standard approaches for these long segment proximal ureteral strictures such as ileum interposition and auto transplantation are technically challenging, highly invasive and therefore associated with a significant morbidity [2, 3, 4].

While buccal mucosa grafts (BMG) in urethral reconstruction are well established, only few small series for BMG in ureteric stricture have been reported. While showing promising results, these studies were flawed by inhomogeneous cohorts of patients with different kinds of strictures like uretero-pelvic junction (UPJ) obstruction, proximal und mid-ureter strictures that were treated with different techniques such as onlay ureteroplasty or augmented end-to-end-anastomosis.

Even though buccal mucosa harvesting is well established and straightforward current guidelines still do not recommend BMG ureteroplasty as an equal alternative to more invasive alternatives such as ileum interposition or renal auto-transplantation [3, 4, 6].

In the current study, we present a small but homogeneous series of patients with long proximal ureteral strictures who underwent a standardized technique of open ureteroplasty with ventral buccal mucosa graft (OU-BMG).

Our reported cases show the heterogeneity the origin of proximal strictures. As shown in our report, severe strictures can occur iatrogenic after ureteroscopy (e.g., ureteric injury; submucosal migration of stone fragments) or retroperitoneal lymphadenectomy and should therefore be discussed with patients prior to such interventions. Further etiologies might be inflammation, ischemia, radio-chemotherapy, and long standing impacted stones [7, 8].

For small strictures endoscopic management with dilatation or laser therapy can be an option.

If endoscopic treatment options fail BMG can be an option next to ileum interposition. In most of the cases (spiral) Boari flaps, which are an excellent option for distal or miduretericstrictures will not be possible for treating proximal strictures. Other options such as replacement with fallopian tubes, vein grafts or biodegradable material still remain experimental [1, 9, 10].

Ileum interposition is complicated by a high frequency of early postoperative bowel movement disorders and involves the danger of intestinal anastomosis insufficiency. Furthermore, patients complain of mucus obstruction, and recurrent urinary tract infections are the result of vesicoureteral reflux [2, 4]. Hypochloremic acidosis may occur even in patients with normal renal function (4%). Additional long-term complications include fistula formation (5%), renal failure with dialysis (2%), small bowel obstruction (8%) and anastomotic stricture (2%) [2, 4].

Renal auto transplantation is technically challenging and bears the risk of damaging renal vessels leading to significant loss of renal function. Overall morbidity rate is 45%, mainly due to hemorrhagic complications (10%) and transplanted kidney failure (10–12%). Surgical re-intervention is necessary in about 25% [3, 5, 6, 11].

At the same time the use of BMG has found wide acceptance with excellent results and has become a gold standard in the reconstruction of urethral strictures [12, 13, 14].

However, for long proximal ureteral strictures the use of BMG has still not drawn attention yet. One of the reasons might be that the incidence of long segment proximal strictures compared to more common and less complicated distal strictures is extremely low [12, 15, 16, 17, 18].

Hence, only few series, mainly single case reports or small cohorts (5–19 patients) on BMG in ureteric reconstruction have been published to date (Table 4) [15, 16, 17, 18, 19, 20, 21].

Table 4
Literature overview

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Success rates of these studies are excellent and range between 83% and 100% and no major complications occurred [15, 16, 17, 18, 19, 20, 21]. Some of the recent studies have described a robotic assisted laparoscopic approach [19, 21]. However, many patients who need a proximal ureteral reconstruction have had major surgery before and may not be eligible for laparoscopic surgery. Furthermore, it can be assumed, that worldwide still most of operations are performed using an open approach.

All of the published series have some limitations which are typical for rare diseases: inhomogeneity of the treated patients with different localizations (Table 4) and origins of strictures (e.g., previous radiation), various techniques of BMG graft placement (Table 4), and the lack of structured information of the postoperative renal function [15, 16, 17, 18, 19, 20, 21].

The use of BMG for ureter reconstruction was first described in 1999 [16]. Table 4 provides an overview of all studies to date. Similarly, another group proposed an onlay graft technique for patients mainly with mid-ureter strictures (4 out of 6) or UPJ obstruction (Table 4) [15]. Surgical technique varied between retroperitoneal and intraperitoneal approach. The most recently published series reported on a robotic assisted laparoscopic approach [19, 21]. This series represents the largest number or treated patients to date (n=19 patients). However, the authors included diverse techniques (Table 4) and used computed tomography (CT) scan for follow-up, whereas a renal scan was proposed but not consequently performed to assess ureteral patency. Therefore, consistent information on postoperative renal function is lacking.

To address these issues, the current series presents the result of one single standardized surgical technique in patients with comparable types of strictures in the proximal third of the ureter. As some of the patients had retroperitoneal lymphadenectomy in their medical history, we preferred a transabdominal open approach through a midline incision for all patients to establish a standard technique. Even though initial placement of nephrostomy tubes instead of double-J stents may be beneficial in these cases due to better intraoperative delineation of the stricture area, all patients presented at our tertiary referral center already with double-J stents in place and at least one attempt of endoscopic dilatation and double-J removal. Ureteric strictures following retroperitoneal lymphadenectomy are mainly due to tissue ischemia and usually require complete excision and total replacement. However, in this series we tried to adhere to our standard protocol even in these cases. The described technique represents an adoption of the principle of open graft urethroplasty to the ureter. Thus, it is easy to perform for surgeons who are familiar with urethral surgery. As in urethroplasty, there is no consensus about the positioning of the graft. In our center, a ventral grafting is preferred in order to keep surgery as simple as possible. As described by Naude [16], an omentum wrap was performed for better blood supply and prevention of urinary leakage. Our protocol included standard retrograde pyelography and ureteroscopy in order to prove ureteral patency and to control if grafting was successful. The time point of double-J catheter removal was at a median of 62 days. This seemed to be a safe time point for such an intervention because a complete wound healing can be expected. However, it might well be that the removal of the double-J catheter could be removed earlier. This should be investigated in future studies.

We found a similar image of a pink mucosa (suggesting healthy tissue) with a dorsal whitish strip of the original and scarred ureter in all cases, resembling the findings of urethroscopy after BMG-urethroplasty (Fig. 3A).

With regard to the postoperative functional outcome, preservation of renal function is of utmost importance. Consequently, all patients underwent renal scintigraphy one year after surgery showing no signs of obstruction or loss of renal function in all patients. In our opinion, anatomical examinations like CT scan, magnetic resonance imaging or intravenous pyelography are of secondary importance as long as renal function has been proven to be unimpaired as long as patients are asymptomatic. Thus, we omitted these examinations, particularly because no patient showed signs of obstruction in the follow-up ultrasound.

In case of recurrent strictures after BMG surgery, we would first try to manage the stricture with an endoscopic approach (e.g., dilatation, laser). However, in case of recurrent long strictures we would then consider an ileum interposition.

The strength of this study is based on the thorough follow-up schedule, which therefore adds another important piece of evidence towards the use of BMG as a standard treatment option.

The main limitation of the present study is the sample size, which at the same time is similar to previous reports in BMG ureteroplasty and might most likely be due to the low incidence of this rare disease. Finally, it the applicability of this technique is limited only for passable strictures with a minimal lumen and might not be useful for strictures with nearly total obliteration.

We conclude that OU-BMG is a safe technique with excellent surgical and functional outcomes for patients with long segment ureteral strictures. Hence, the application of this technique should be encouraged and regarded as one of the standard options in case of this rare problem.