| Abstract|| |
Ureteric stents are widely used in renal transplantation to minimize the early urological complications. Ureteric stents are removed between two and 12 weeks following transplantation, once the vesico-ureteric anastomosis is healed. Ureteric stents are associated with considerable morbidity due to complications such as infection, hematuria, encrustations and migration. Despite the patient having a regular follow-up in the renal transplant clinic, ureteric stents may be overlooked and forgotten. The retained or forgotten ureteric stents may adversely affect renal allograft function and could be potentially life-threatening in immunocompromised transplant recipients with a single transplant kidney. Retrieving these retained ureteric stents could be challenging and may necessitate multimodal urological treatments. We report three cases of forgotten stents in renal transplant recipients for more than four years. These cases emphasize the importance of patient education about the indwelling ureteric stent and possibly providing with a stent card to the patient. Maintaining a stent register, with a possible computer tracking system, is highly recommended to prevent such complications.
|How to cite this article:|
Bardapure M, Sharma A, Hammad A. Forgotten ureteric stents in renal transplant recipients: Three case reports. Saudi J Kidney Dis Transpl 2014;25:109-12
|How to cite this URL:|
Bardapure M, Sharma A, Hammad A. Forgotten ureteric stents in renal transplant recipients: Three case reports. Saudi J Kidney Dis Transpl [serial online] 2014 [cited 2020 Jul 10];25:109-12. Available from: http://www.sjkdt.org/text.asp?2014/25/1/109/124514
| Introduction|| |
Placement of ureteric stent in the construction of an ureteronoecystostomy in reduces urinary leak and obstruction in the early post-transplant period. ,, Despite improvement in stent technology, ureteric stents are still associated with significant morbidity. Generally, stents are removed 2-12 weeks post-renal transplantation, once the vesico-ureteric anastomosis is thought to have healed. Urinary tract infection (UTI) is more commonly seen, but others problems include lower urinary tract symptoms, obstructive uropathy, stent migration and urinary sepsis. We report three cases of forgotten ureteric stents and their successful retrieval after several years following renal transplantation. Also, we highlight the judicious use of extra-corporal shock wave lithotripsy (ESWL) in one of the cases. A prophylactic antibiotic was used in all three cases during cystoscopic removal of ureteric stents to prevent bacteremia and sepsis considering the immunocom-promised status of the renal transplant recipient.
| Case Reports|| |
A 34-year-old female had end-stage renal failure due to neurogenic bladder secondary to spina bifida. She had cadaveric renal transplantation in the year 2004. Ureteroneocystostomy was fashioned using the Lich technique and a six French ureteric stent was placed to protect the vesico-ureteric anastomosis during the operation. The post-operative period was uneventful. The renal allograft function remained stable, with a serum creatinine of 90 μmol/L.
She had a regular follow-up with the renal transplant team and nephrology team at a satellite hospital. She remained well and asymptomatic, with a stable graft function. Thirty-six months following renal transplantation, she presented with recurrent episodes of UTIs, with five episodes in the year 2007 alone. A Doppler ultrasound scan of the transplant kidney revealed mild hydronephrosis and an echo-bright stent was visualized in the renal pelvis [Figure 1]. X-ray of the kidney, ureter, bladder (KUB) plain radiograph revealed a retained stent. Radiological report confirmed the generalized encrustation of the stent [Figure 2]. A urological opinion was sought and ESWL was suggested to fragment the encrustations of the upper curl of the ureteric stent prior to the removal. Following two sessions of ESWL under prophylactic antibiotic use, good fragmentation of the encrustation was achieved, as evident on subsequent X-ray KUB, as per the radiologist's opinion. The stent was removed cystoscopically without any complications under antibiotic prophylaxis.
|Figure 1: Ultrasound of transplant kidney with upper curl of ureteric stent in renal pelvis.|
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|Figure 2: Plain X-ray of abdomen showing encrusted ureteric stent in transplant kidney.|
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A 55-year-old male with end-stage renal failure secondary to hypertensive nephrosclerosis had his renal transplantation in the year 2004. Post-operative recovery was unremarkable and he had stable graft function. Three years following his renal transplantation, he presented with irritating bladder symptoms during follow-up in the renal transplant clinic. Urine microscopy and culture showed no evidence of bacterial growth. However, he continued to suffer from bothersome lower urinary tract symptoms, mainly in the form of urinary frequency, urgency and decreased urinary stream. He was assessed in the urology clinic and had uroflometry performed. He was commenced on an alfa-blocker and his symptoms improved marginally. An X-ray KUB was performed to exclude urinary tract calculi, which, to everybody's surprise, revealed an indwelling ureteric stent without any encrustations. Retained stent was removed endoscopically under general anesthesia under antibiotic cover as per microbiology advice.
A 35-year-old diabetic gentleman underwent combined renal transplantation in 2003. This gentleman made a steady recovery and his serum creatinine at the time of discharge was 110 μmol/L and creatinine clearance was 50 mL/min. He was under regular follow-up by the transplant team. The renal allograft function remained stable over the years. Five years following renal transplantation, he presented with hematuria and irritating bladder symptoms. Urine microscopy and culture confirmed UTI. An X-ray plain film revealed a retained ureteric stent. The stent appeared clean without any radiological evidence of encrustations or calcifications, and the stent was retrieved cystoscopically without any complication.
| Discussion|| |
Although the use of ureteric stent in renal transplantation patients is not universal, its use has been shown to reduce early urological complications. ,, An ureteroneocystostomy is constructed over an ureteric stent, which was introduced to minimize anastomotic leak and ureteric obstruction. Urological complications are more frequently encountered in the first three months following renal transplantation, and can significantly compromise the graft function.
Prophylactic ureteric stenting in renal transplantation is associated with early complications such as UTI, hematuria and irritating bladder symptoms. Late complications include encrustation, migration, fragmentation and, rarely, septicemia. Sometimes, ureteric stents can be overlooked or forgotten. Although any foreign body retained in the body for more than 29 days is called an implant, there is no definition for a retained or forgotten ureteric stent.
There is no universal consensus with regard to the timing of removal of stent following transplant, and various studies report stenting duration between one and 12 weeks. Reducing the duration of stenting from four weeks to two weeks avoids complications associated with prolonged use of stent without compromising the potential benefit of the ureteric stent in minimizing the early urological complications. It obviates the risk of forgotten stent as well. It is recommended that stents be removed two to four weeks following transplant to prevent septic complications. 
Another potential complication is encrustation and stone formation, necessitating multi-modal therapy to retrieve the stent intact. , Encrustation and calcification are directly related to indwelling time and other host factors such as bacterial colonization, biofilm on stent and history of lithogenesis. Urinary constituents and bacterial colonization also play a role in encrustation of stent. The ureteric stents are rapidly covered with a bacterial biofilm when in contact with urine, which can lead to UTI. Urea-splitting organisms increase the urinary pH, which in turn facilitates the deposition of calcium magnesium phosphate crystals over the biofilm. 
In a study, El-Faqih et al after examining the retrieved indwelling stents noted that 9.2% of stents removed within six weeks of insertion had encrustations. This figure increased to 47.5% for those stents removed between six and 12 weeks.  In cases of retained or forgotten stents, risk factors for possible encrustations should be evaluated and a preliminary X-ray KUB radiograph should be obtained to exclude encrustation. 
In this case series, all three patients had minimal symptoms and tolerated the indwelling retained stents for a fairly long duration. In the end, two patients developed recurrent UTIs caused by a single organism. This could due to the formation of a bio-film and subsequent colonization of the stent by the bacteria in these immuno-compromised renal transplant recipients.
Occasionally, stent encrustation may not be detected on radiological imaging, and this may prevent uncoiling of the upper curl. If there is no evidence of encrustation radiologically, the stent can be removed cystoscopically under antibiotic cover. Any sign of encrustation over the stent would make it inadvisable to attempt stent removal. As encrustation makes the stent brittle, and it can easily fragment, there is always the risk of ureteral injury.  Sometimes, linear calcifications are hard to identify on plain X-ray and, in such cases, non-contrast computerized tomography scan may be helpful. 
ESWL was first described for the management of calcified stents in 1990 in native kidneys.  In renal transplant recipients, ESWL was first used in 2002 for stone fragmentation with good results.  ESWL may be used in renal transplant patients to treat low-volume encrustations, provided there is optimal renal allograft function before attempting stent removal. As demonstrated in case no. 1, the stent was removed following two sessions of ESWL.
Considering the immuno-compromised status, there is an increased risk of bacteremia and septicemia. After successfully treating the UTI, prophylactic antibiotics were administered based on the urine culture results during ESWL and endoscopic stent removal.
Ureteric stents in renal transplant patients can be overlooked, despite being under regular follow-up. Management of the forgotten stent in renal transplant patients can be challenging and needs careful work up and planning.
To prevent the ureteric stents being overlooked, use of stents may be restricted to a few selected cases A robust system to highlight the stents used in renal transplant needs to be developed. Patient education, stent register and computer tracking may be useful in preventing such complications. A stent card may be given as this makes the patient aware of an indwelling ureteric stent as well as serving as a reminder to the transplant team.
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Renal Transplant Unit, Royal Liverpool University Hospital, Liverpool
[Figure 1], [Figure 2]