Since their introduction in 1967, ureteral stents have remained one of the most commonly used tools by urologists for relieving renal and ureteral obstruction [7]. Regardless of the reason for stent placement, patient education, clear postoperative instructions, and meticulous record-keeping to ensure timely removal are essential to avoid prolonged stent retention.

Long-term retention of stents can result in complications such as pain, encrustation, obstruction, UTIs, and even loss of kidney function. Encrustation is a multifactorial process influenced by biofilm formation, patient-specific risk factors (e.g., a history of stones, UTIs, or pregnancy), and the properties of the stent material. It occurs due to the deposition of calcium oxalate or uric acid on the stent’s surface. Importantly, the duration of stent indwelling is a critical factor, with some studies showing that the rate of encrustation increases exponentially over time [7].

Periodic replacement or timely removal of ureteral stents is crucial to prevent complications such as encrustation, which increases with extended indwelling time. Research shows encrustation rates rise from 9.2% at less than six weeks to 76.3% beyond 12 weeks. Early removal, typically within three months, is recommended to avoid severe complications. Studies also highlight removal challenges, with 42.8% of stents becoming difficult to remove after four months and cases of irremovable stents after prolonged use, averaging 20 months [4,9–11].

The radio-opaque nature of ureteral stent encrustation makes standard kidney, ureter, and bladder (KUB) X-rays the first-line imaging modality for detection. However, ultrasound or CT scans are often utilized subsequently to precisely locate the encrustation relative to the ureter and/or stent. Once the extent of encrustation is identified, grading systems are used to assess the complexity of removal, followed by the application of a treatment algorithm to determine the most appropriate surgical technique [12].

The Forgotten, Encrusted, Calcified (FECal) System categorizes stent encrustation into five grades. Grade I represents minimal encrustation confined to the distal stent pigtail, while Grade V indicates extensive circumferential encrustation encasing the entire stent. The proposed treatment options range from cystoscopy and stent removal for minor encrustations to more invasive procedures such as ESWL, PCNL, cystolitholapaxy, URS, or combinations of these for severe cases. In instances where renal function is reduced to <20%, nephrectomy may be necessary [8].

The KUB System evaluates encrustation based on severity and location within the urinary tract [13]. A recently published treatment algorithm integrates both the FECal and KUB Systems, providing a comprehensive approach to managing stent encrustations [12].

In our case, and because of the patient's condition (single kidney), the endoscopic approach was chosen because it causes less damage and follows the natural urine pathway. Urologists with advanced training in endourology can typically manage forgotten double-J stents using endoscopic techniques, reserving open surgery as a last resort if endoscopic procedures are unsuccessful [4].

The removal of retained and encrusted ureteral stents is often surgically challenging, requiring various multimodal approaches to ensure patients are free of both stents and stones. Despite the prevalence of this issue, the available evidence for optimal treatment mainly consists of case reports and small series. While no universally accepted guidelines exist, several authors have proposed algorithmic approaches to facilitate successful stent removal.

Retained ureteral stents often necessitate multiple endourological procedures for removal, with reported averages ranging from 2 to 4.2 procedures to achieve a stent- and stone-free outcome [14]. However, single-step approaches have also demonstrated success. These methods typically involve retrograde URS combined with Ho-YAG laser lithotripsy to manage stent calcifications or fragment the stent itself, creating more space in the ureter for instruments. In a series of 36 patients, URS successfully removed encrusted stents in a single anesthetic [10].

The use of smaller URS has been shown to reduce the risks of mucosal injury, ureteral perforation, and ureteral avulsion, while potentially eliminating the need for PCNL, which is associated with higher morbidity and complication rates [4].

The development of flexible URS and Ho:YAG lasers has improved stent removal by enabling better observation and manipulation in the renal pelvis. While rigid URS can effectively remove proximal encrustation, it carries the risk of ureteral injury, making flexible URS with ureteral access sheath (UAS) a safer choice after confirming no adherence to the middle ureter.

Preoperative stenting is beneficial for ureter dilation, allowing for the insertion of larger caliber UAS and facilitating URS. UAS also reduces intrarenal pressure, improves irrigation flow, shortens operative time, and aids in retrieving stone fragments. Inserting a ureteral stent beside an encrusted one before URS is particularly helpful for drainage, dilation, and safe removal, especially in cases with significant encrustation. This approach minimizes risks such as ureteral stricture and optimizes surgical outcomes [15].

Despite the success of URS in many cases, a percutaneous approach may still be required for patients with significant proximal coil stone burdens and large renal stones. The degree of proximal loop encrustation has been correlated with a higher likelihood of requiring PCNL, multiple procedures, and an increased risk of surgical complications [16].

In a multicenter retrospective study by Pais et al., involving 38 renal units undergoing PCNL for encrusted ureteral stent removal with a mean dwell time of 28.2 months, PCNL alone was sufficient in only 21% of cases. Adjunctive procedures were often necessary, either during the PCNL or as separate operations, to ensure complete stent removal [16].

The "Tri-Glide" technique is an innovative approach for managing complex encrusted stent extractions. Its key advantage lies in modified patient positioning, enabling easier guidewire passage in cases of severe shaft encrustation (retrograde or antegrade fashion). This method is especially effective when stent coils cannot fully uncurl or when severe encrustation or ureteral narrowing prevents ureteroscope advancement [17].

To prevent the serious consequences of missed ureteral stents, several strategies have been developed:

1. Advances in Stent Design and Materials: Modern stents are made from biocompatible materials like silicone and nitinol. Research is underway on biodegradable materials such as chitosan and polyglycolic acid to address complications from long-term use. Innovations in stent coatings and designs aim to reduce infection, encrustation, and pain, though widespread adoption of these materials will take time.
2. Electronic Tracking Systems: Computerized databases with reminder systems, like the “traffic-light” method, improve stent management. Compared to manual logbooks, these systems significantly reduce cases of prolonged stent insertion caused by missed appointments or follow-up errors.
3. Patient Education and Reminders: Educating patients about the risks of stents and providing direct reminders help mitigate follow-up lapses. Strategies include wristbands with barcodes for tracking, mobile applications for reminders, and online platforms to monitor appointments and reduce complications due to forgotten stents.

These methods collectively improve patient safety and stent management, minimizing risks associated with delayed removal [18–20].