Retained ureteral stents are one of the most frustrating and feared scenarios following endourologic surgery. Failure to remove or exchange a ureteral stent in a timely manner can lead to stone formation anywhere along the stent, making them impossible to remove,¹ in addition to complications such as infections and loss of renal function. Attempts to aggressively retrieve a heavily encrusted stent can lead to stent fracture and even complete ureteral avulsion as the proximal coil may not release. Risk factors for stent encrustation include prolonged stent dwell time, history of nephrolithiasis, smaller stent diameter, and pregnancy.² Vulnerable populations for retained stents include those with psychiatric illnesses, incarcerated patients, and individuals with limited medical insurance.

Multiple scoring systems have been developed to classify degrees of stent encrustation. One of the earliest is the FECal (forgotten, encrusted, calcified) model, which grades the pattern of encrustation based on CT or kidney, ureter, and bladder x-ray and suggests appropriate endourologic management.³ This system is useful to structure one’s approach to the encrusted stent and stratifies the approach into 3 components: (1) proximal coil, (2) distal coil, and (3) ureter. The distal coil can typically be released by laser cystolitholapaxy, while the proximal coil can be released by either extracorporeal shockwave lithotripsy or percutaneous nephrolithotomy (PCNL). Depending on the approach, ureteral calcifications can be lasered with either retrograde or antegrade ureteroscopy. Failure to completely mobilize the stent can lead to ureteral avulsion during stent removal. After the stent has been removed, additional procedures may be required to address residual stone burden. Of note, if the kidney with the retained stent has poor function, nephrectomy can be considered instead.

Our approach to retained stents is to first obtain a CT scan to gauge the severity of encrustation and plan the extent of lithotripsy required. Ideally, we aim to perform total endoscopic management under a single anesthetic. When encrustation is present at both ends, we begin with the patient in dorsal lithotomy and perform cystolitholapaxy on the distal coil. The ureter is next cleared by advancing a semirigid ureteroscope alongside the stent and performing laser lithotripsy. A flexible ureteroscope can also be used, but this can be challenging depending on the degree of encrustation and mucosal inflammation. If the proximal coil can be reached with the ureteroscope, it can be freed so that the stent can be removed entirely in a retrograde manner. Alternatively, the distal coil can be amputated and removed via the urethra, or in the case of a female, withdrawn to the meatus and cut externally. The patient is then positioned prone to obtain percutaneous renal access. A preoperative percutaneous nephrostomy tube (PCN) placed by interventional radiology should be strongly considered if a patient with a retained stent presents with signs of infection or stone burden on the coils is severe enough to potentially hinder obtaining intraoperative percutaneous access if a PCNL is planned. Depending on the stone burden, we either perform standard or mini-PCNL. The rigid nephroscope is used to perform lithotripsy on the proximal coil. Antegrade flexible ureteroscopy is then used to mobilize the ureteral portion of the stent so that the stent can be retrieved through the percutaneous tract. Residual stones are then cleared and either a PCN or new ureteral stent is left in place with the shortest possible dwell time. Figures 1 and 2 show example cases of patients with retained stents managed using this approach.

Pais et al reported the largest North American series on PCNL for management of retained stents.⁴ Eighty percent of cases required either concurrent cystolitholapaxy or ureteroscopy to mobilize the stent. Overall stone-free rate was 63% and one-third needed a second-stage PCNL. The top reason for retained stents was that the patient was “unaware,” highlighting the importance of patient education.

Multiple initiatives for preventing retained ureteral stents have been proposed including electronic medical record modules, cellular applications, and wrist bands.⁵ These proposals helped identify instances where there was a failure to arrange and/or confirm timely follow-up for stent removal. However, the incidence of patients missing stent removal appointments is consistently low (<1%) and none of the above strategies have demonstrated a reduction in postoperative morbidity.

In summary, retained stents are rare but can lead to significant morbidity including loss of the renal unit. The majority of cases can be addressed using a combination of cystolitholapaxy, ureteroscopy, and PCNL, preferably under 1 anesthetic. Given the complexity of management, careful patient counselling is essential.