Background {#Sec1}
==========

The development of ureteral calculi after Yang-Monti ileal ureter reconstruction has not been reported. The treatment of ureteral stones is technically challenging, especially for surgeons with minimal experience in such procedures. We used ureteroscopy combined with laser lithotripsy to successfully treat a patient with ipsilateral distal ureteral calculi and ipsilateral lower calyceal calculi after Yang-Monti ileal ureter reconstruction due to long-segment ureteral stenosis.

Case presentation {#Sec2}
=================

The patient was a 48-year-old man with a 4-year history of ureteral calculi and a 2-year history of ureteral stenosis for which he had undergone multiple surgeries. Ureteral calculi recurred many times, resulting in repeated ureteral stricture that was treated three times by ureteroscopic holmium laser lithotripsy, and twice by ureteroscopic balloon dilation. He had been admitted to our hospital for left ureteral stenosis in June 2015. Examination at that time revealed a 20-cm stenosis in the middle and lower segments of the ureter. Noncontrast computed tomography showed inflammation and adhesion around the kidney as a result of multiple ureteral surgeries, making the patient unsuitable for autologous kidney transplantation. Yang-Monti ileal ureter reconstruction was performed, and the 6-month postoperative examination revealed left ureteral patency (Fig. [1](#Fig1){ref-type="fig"}), stable renal function, normal electrolyte levels, and no obvious mucus-like flocculation in the urine.Fig. 1Left ureteral patency at 6 months after Yang-Monti ileal ureter reconstruction

Ten months after the Yang-Monti ileal ureter reconstruction, the patient developed left lumbar pain and discomfort. Noncontrast computed tomography showed that the left kidney had a slightly smaller volume than the right, and that the left renal pelvis and renal calices were slightly expanded and hydronephrotic. Two nodule-shaped high-density shadows were present in the lower renal calyx; the diameter of the larger shadow was 4 to 5 mm. A liquid-density shadow was seen in the ileal lumen of the left ureter, with a small nodule-shaped high-density shadow (3-mm diameter) at its end. Corticomedullary development was good. During excretion, accumulation of contrast agent could be seen in the left renal pelvis, renal calices, and ureter (Figs. [2](#Fig2){ref-type="fig"}, [3](#Fig3){ref-type="fig"} and [4](#Fig4){ref-type="fig"}). The serum creatinine concentration was normal.Fig. 2Two nodule-shaped high-density shadows in the lower renal calyx (indicated by the arrows)Fig. 3A nodule-shaped high-density shadow in the ileal lumen of the left ureter (indicated by the arrow)Fig. 4A nodule-shaped high-density shadow in the ileal lumen of the left ureter (indicated by the arrow)

The patient was placed in the lithotomy position under general anesthesia. The ileal ureterovesical reimplantation opening was smoothly entered under direct vision using a 9.5-Fr semirigid ureteroscope (Richard Wolf Medical Instruments, Knittlingen, Germany). Ureteroscopic examination revealed that the calculi were attached to surgical sutures located from 1 cm from the inner end of the ileal ureter to the ureteral opening, and that the sutures were embedded under the ileal ureteral mucosa in a ring shape (Fig. [5](#Fig5){ref-type="fig"}). A basket extractor \[NGage Nitinol Stone Extractor (NGE-017115), 1.7 Fr × 115 cm; Cook Medical, Bloomington, IN, USA\] was used to hold the calculi and sutures, which were then broken up with a holmium laser (0.6 J, 30 Hz, 200-μm fiber; 60-W LISA Sphinx Holmium:Yttrium-Aluminium-Garnet Laser System, LISA Laser Products, Katlenburg-Lindau, Germany) and completely removed (Figs. [6](#Fig6){ref-type="fig"}, [7](#Fig7){ref-type="fig"}). Ureteroscopy revealed that the Yang-Monti ileal ureter had a thick and straight lumen, smooth mucosa, and no obvious folds or anastomoses between sections (Fig. [8](#Fig8){ref-type="fig"}). Using a Zebra guidewire (Boston Scientific, Marlborough, MA, USA) for guidance, a flexible ureteroscope working sheath (12/14 Fr × 115 cm, M006250226; Boston Scientific) was imbedded and inserted into the left renal pelvis under direct vision using a digital flexible ureteroscope (8.5 Fr, 11278VS; Karl Storz, Tuttlingen, Germany). Using a filling pump (26331020--1; Storz Medical, Tägerwilen, Switzerland) with an infusion pressure of 80 mmHg, the two lower calyceal calculi were identified, broken up, and removed. As a preoperative urine culture had revealed a urinary tract infection, antibiotics were administered postoperatively. Additionally, a 5-Fr ureteral catheter (Kangge Medical Instruments, Shanghai, China) and a urinary catheter were left indwelling, and were removed on postoperative day 3.Fig. 5The calculi were attached to surgical sutures, and the sutures were embedded under the ileal ureteral mucosaFig. 6A basket extractor was used to hold the calculi and suturesFig. 7The calculi and sutures were broken up with a holmium laserFig. 8The Yang-Monti ileal ureter had a thick and straight lumen and smooth mucosa

Discussion and conclusion {#Sec3}
=========================

A previous study investigating minimally invasive treatment of ureteral calculi following ileal neobladder surgery reported that the cause of calculi development may be related to the presence of foreign bodies (e.g., ureteral stents and sutures) \[[@CR1]\]. Furthermore, the generation of ileal ureteral calculi also has a very close relationship with intestinal mucous \[[@CR2]\]; when the ileal anastomosis is bulky, the intestinal mucous secreted in the ileal segment near the kidney during bowel movements is more likely to enter the kidney, accumulate in the renal pelvis within the calyx, and become a matrix or core of stone formation, along with urine salt deposition and stone formation \[[@CR2]\]. If the ileal replacement ureter is too long and the postoperative replacement urine becomes stored in the ileum, this urine combines with the large amount of mucus secreted by the intestinal tract to form calculi, and ureteral calculi in the ureteral diversion may be formed by renal calculi falling through the urine drainage \[[@CR3]\]. In the present case, the absorbable suture in the lower ileal ureteral segment from the previous ureteral reconstruction had not degraded or fallen off, and so served as a matrix or core for calculi formation; its long-term contact with urine resulted in urinary salt being continuously deposited to form calculi \[[@CR4], [@CR5]\]. The lower ileal ureteral calculi were successfully removed using a rigid ureteroscope combined with holmium laser lithotripsy to remove the sutures and attached calculi.

During the holmium laser removal of sutures, it is important to determine the shape and direction of the suture, cut the suture from its root near the ileal ureteral mucosa, and check the integrity of the suture to prevent leaving residual suture that will again enable calculi to form. Suture removal must be performed under direct vision. As the suture moves along with the movement of the perfusate, the suture must be fixed with a basket extractor to create adequate tension and thus prevent the suture from moving; this improves the success rate of suture removal, and reduces the risk of ileal ureteral injury.

A digital flexible ureteroscope was entered into the left renal collection system. As the calculi were small (maximum diameter of 5 mm) and oval-shaped with smooth surfaces, we were able to use a basket extractor to cover and remove the calculi. During removal, we discovered that the calculi had diameters that were larger than that of the working sheath for the flexible ureteroscope; hence, we covered each calculus and removed it together with the working sheath of the flexible ureteroscope. Using intraoperative ureteroscopic guidance, a 5-Fr double-J stent was placed upon completion of the surgery.

The key points gained from our experience are as follows. (1) The thinnest holmium laser fiber with the appropriate energy for cutting should be selected, so that the laser fiber can pass through the gap between the basket extractor and the ureteroscopic operation channel. It is best to conduct an in vitro analysis of suture materials, and then choose the best energy setting for cutting. The appropriate energy setting is that which can cut the suture while preventing damage to the ureter. (2) Good intraoperative control of the perfusion pressure must be maintained. Excessive pressure causes dilatation of the reconstructed ureteral lumen, increased pressure in the renal pelvis and renal calices, and an increased risk of postoperative infection. (3) The ileal ureter has a large lumen diameter. Even if the diameter of the intestinal canal is cut using the Yang-Monti method, the reconstructed ureteral lumen still has a large diameter, and thus the rigid ureteroscope, flexible ureteroscope, and working sheath of the flexible ureteroscope can be successfully retrograded to the renal pelvis. When the diameters of the calculi are smaller than the diameter of the ureteral lumen, a basket extractor can be used.

In summary, ureteroscopy combined with laser lithotripsy seems to be a valuable option for the management of urinary calculi following Yang-Monti ileal ureter reconstruction.

We thank Kelly Zammit, BVSc, and Angela Morben, DVM, ELS, from Liwen Bianji, Edanz Editing China (<http://www.liwenbianji.cn/ac>), for editing the English text of a draft of this manuscript.

Funding {#FPar1}
=======

This study was supported by the Guizhou Province Science and Technology Fund.

Availability of data and materials {#FPar2}
==================================

Not applicable.

Declarations {#FPar3}
============

No conflict of interest exits in the submission of this manuscript, and the manuscript has been approved by all authors for publication. The work described herein is original research that has not been published previously and is not under consideration for publication elsewhere, in whole or in part. All authors of the manuscript have read and agreed to its content and are accountable for all aspects of the accuracy and integrity of the manuscript in accordance with ICMJE criteria, and all agree to the terms of the BioMed Central License Agreement and Open Data Policy.

ZW wrote the first draft of the manuscript. ZS, GL, YT, and XY reviewed the manuscript and were involved in its critical revision before submission. All authors read and approved the final manuscript.

Ethics approval and consent to participate {#FPar4}
==========================================

Not applicable.

Consent for publication {#FPar5}
=======================

Written informed consent for publication was obtained from the patient.

Competing interests {#FPar6}
===================

The authors declare that they have no competing interests.

Publisher's Note {#FPar7}
================

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
