自從芬尼開始介紹使用雙丁型輸尿管導管開始，它在近二十年間已成為泌尿科手術常置放的導管，由於其經濟、可靠及安全的特性，因此它廣泛使用於輸尿管阻塞、狹窄、廔管及泌尿內視鏡手的病例中。它應於六至八週內拔除，超過期限未能及時拔除，則很容易發生併發症，且增加拔除的困難度。 本文共報告七例過期未拔的雙丁型輸尿管導管的病例，皆有結石手術且植入丁型輸尿管導管的病史，最長期間為六年，最短者為兩年，平均為三年半。拔除方法有膀胱鏡兩例、膀胱鏡合併體外震波碎石術者一例，經皮腎造廔術一例、開放手術兩例、及一例因部份導管尖端刺入腎皮質且造成腎結石及腎功能受損而行部份腎切除手術，其實施方法會因導管結石鑲嵌的個別程度而不同，而腎臟部份鑲嵌愈多則所方法愈複雜，且細菌感染及腎臟的功能受損更是常見；因此本文提出細菌感染、導管置放過久及結石病人是導管鑲嵌的危險因子，大量喝水、服用抗生素或某些藥物並不能完全防止其發生，在治療目的達成後及時拔除才是最佳的避免方法，由於導管在體內並無大多不適，因此醫師應教導病人記得回診儘速拔除。

Double-J catheter is widely used in the endourological surgery, since it can lessen the post-operative morbidity and complications. It should be removed within a six to eight week interval, if otherwise, encrustation can occur if there is a delay. Here seven cases of forgotten and encrusted double-J catheter have experienced and all met with problems in the management of catheter removal. All patients had a history of urolithiasis managed by surgical operation or extracorporeal shock wave lithotripsy. The longest period of catheter insertion was six years and the shortest was two years, or an average of three and half a years. Cystoscopies (2), percutaneous procedure (1), ureterotomies (2) partial nephrectomy (1) and extracorporeal shock wave lithotripsy (1) were performed on individual patients according to the independent encrustations of catheter. There was penetration into the renal cortex by the double-J catheter tip in the case of partial nephrectomy, with to the catheter causing renal stone and cortical atrophy. Problems encountered here may be related to the extend of encrustations and catheter conditions such as migration or fracture. Presence of urinary tract infection is common in those cases. There was variable irreversible hydronephrosis after removal of the catheter during follow-up visits. Infection, duration of catheter stay and stone-forming are the risk factors from catheter encrustations, causing problems in the removal of such a catheter. In conclusion, it is better to remove the double-J catheter immediately after termination. Non-removal, from forgetfulness, of the catheter can be hazardous and cause renal damage.