Yang-Monti Ileal Ureter
The Yang-Monti ileal ureter uses a short segment of ileum (5–7.5 cm) detubularized and retubularized transversely to create a narrow-caliber conduit suitable for bridging long ureteral defects (8–18 cm). The reconfiguration trades bowel diameter for length, overcoming the principal drawbacks of the classic ileal ureter: excessive mucosal surface area, mucus burden, metabolic absorption, and the difficulty of fashioning a nonrefluxing reimplant from a wide bowel tube.[1][2]
Related: see Yang-Monti Channel for the catheterizable-channel application of the same retubularization principle.
Lineage
The Monti principle was originally described for continent catheterizable channels. Yang adapted it to ureteral replacement, and Ali-el-Dein and Ghoneim refined and popularized it for long ureteral defects.[1] The core principle:
- Isolate a short ileal segment (5–7.5 cm) on its mesentery.
- Subdivide the segment into 2 or 3 equal parts.
- Open each sub-segment longitudinally along the antimesenteric border.
- Unfold and lay the opened segments side by side as a flat ileal strip 12–18 cm long.
- Retubularize the strip transversely over a stent into a narrow tube of approximately ureteral caliber.[1][3]
Advantages Over the Classic Ileal Ureter
| Drawback of classic ileal ureter | How Yang-Monti addresses it |
|---|---|
| Long bowel harvest (15–25 cm) → metabolic / nutritional burden | 5–7.5 cm suffices.[1][2][4] |
| Wide caliber requires tapering | Retubularized tube has near-ureteral diameter; tapering not required.[1] |
| Large mucosal surface → mucus obstruction | Smaller mucosal area → less mucus.[1][4] |
| Hyperchloremic metabolic acidosis | Smaller absorptive surface — no metabolic complications in the largest long-term series.[5] |
| Difficult / impossible nonrefluxing reimplant | Narrow caliber permits submucosal-tunnel ileovesicostomy.[1] |
| Bowel length limits combinability | Short segment combines well with Boari flap or psoas hitch.[2] |
Indications
For long ureteral defects (8–16 cm) when simpler reconstructive options (ureteroureterostomy, Boari flap with psoas hitch, transureteroureterostomy) are insufficient or have failed.[5][2]
| Etiology | Frequency / notes |
|---|---|
| Iatrogenic strictures | Most common — ~44% of cases.[5] |
| Bilharzial (schistosomal) strictures | [1] |
| Tuberculous strictures | [1] |
| Retroperitoneal fibrosis | [5] |
| Radiation strictures | [6] |
| Traumatic ureteral injury (incl. gunshot) | [5] |
| Malignancy-related ureteral loss | [5] |
| Failed prior pyeloplasty or reimplant | Particularly pediatric.[7] |
Patient Selection and Contraindications
- Renal-function threshold. Relative contraindication when eGFR <40 mL/min/1.73 m² — patients with CKD stage 3b or worse showed deterioration of renal parameters in the Ali-El-Dein 2021 series.[5]
- Safe in CKD stages 1–3a and in the solitary kidney with adequate function.[5]
- Prior bowel surgery or radiation enteritis may limit usable ileum.
Surgical Technique
Open, laparoscopic, or robotic.[7][4]
- Bowel isolation. A 5–7.5 cm segment of terminal ileum is isolated on its mesenteric pedicle; restore bowel continuity with an end-to-end anastomosis.[1]
- Subdivision. Divide the isolated segment into 2 equal parts (double Monti) or 3 parts (triple Monti), depending on required length.[1]
- Detubularization. Open each sub-segment along its antimesenteric (paramesenteric) border.
- Reconfiguration. Lay the opened segments side by side and suture them into a continuous flat strip.
- Retubularization. Tubularize the strip over a stent / catheter (typically 8–10 Fr) into a narrow tube.
- Proximal anastomosis. Spatulated end-to-end anastomosis to the renal pelvis or proximal ureteral stump.
- Distal reimplantation. Reimplant the distal end into the bladder via a submucosal tunnel (nonrefluxing ileovesicostomy).[1]
- Stenting. Internal ureteral stent for 4–6 weeks.
- Isoperistaltic orientation is maintained to promote unidirectional flow.[1]
Variations
- Onlay technique. When the native ureteral plate is preserved, the reconfigured strip is used as an onlay rather than full circumferential replacement — preserving native ureteral tissue.[4]
- Double Monti with sigmoid colon. Has been described for total ureteral substitution combined with a Boari flap.[3]
Antireflux Considerations
The narrow caliber is the structural reason submucosal-tunnel reimplantation is feasible — reflux occurred in only 1/10 patients in the original series.[1] When implantation is into an intestinal reservoir rather than the native bladder, antireflux constructs (e.g., a distal nipple-valve technique) are recommended; the requirement is less critical when the native bladder is the implantation site.[8][2]
Long-Term Outcomes
Largest dedicated Yang-Monti series — Ali-El-Dein 2021, n = 36, median follow-up 68 months (range 12–215):[5]
| Parameter | Result |
|---|---|
| Renal function | Significant improvement in serum creatinine, split renographic clearance, and eGFR |
| Hydronephrosis | Improved in most patients on MR urography |
| Metabolic complications | None reported |
| UTI | 28% (10/36) |
| Intestinal obstruction | 2.8% (1/36) |
| Perioperative complications | Clavien-Dindo grades 1–2 only |
| Reflux (with submucosal reimplant) | ~10% (1/10) historically[1] |
| Functional patency | Stable or improved split renal function in >80%[5][3] |
Renal-function improvement extended to patients with CKD stages 2–3a and to solitary kidneys; only 4 patients with CKD stage 3 deteriorated.[5]
Pediatric Application
Laparoscopic Yang-Monti ureteral reconstruction has been performed successfully in children (mean age 8.5 yr, mean defect 5.83 cm), most after failed pyeloplasty. All patients showed improvement of differential renal function without obstruction on diuretic renography; mean OR time 314 min, mean blood loss 25 mL.[7]
Yang-Monti vs Classic Ileal Ureter
| Feature | Yang-Monti | Classic Ileal Ureter |
|---|---|---|
| Bowel segment harvested | 5–7.5 cm | 15–25 cm |
| Conduit length | 12–18 cm | 15–25 cm |
| Conduit caliber | Narrow (ureteral-like) | Wide (bowel-caliber) |
| Tapering required | No | Often |
| Antireflux reimplantation | Feasible (submucosal tunnel) | Difficult / impossible |
| Mucus production | Minimal | Significant |
| Metabolic acidosis risk | Very low / absent | 3.7–4% |
| Bowel-related morbidity | Lower | Higher |
| Functional patency | >80% | ~83% (no further open surgery) |
References:[1][2][3][4][5][6][7][10]
Complications
- Urinary tract infection ~28% — most common.[5]
- Small-bowel obstruction ~2.8% (vs 8.3% in classic ileal-ureter series).[5][10]
- Anastomotic stricture — rare with Yang-Monti; 3.7% reported in classic ileal-ureter series.[10]
- Ureteral fistula — reported in irradiated patients.[4]
- Mucus obstruction — rare due to reduced mucosal surface.[2]
- Renal-function deterioration — 4/36 (11%) in the largest series, primarily CKD stage 3; bilateral reconstruction carries a 3.7× increased risk of worsening renal function.[5][10]
See Also
- Ileal Ureter (classic)
- Yang-Monti Channel (catheterizable-channel application)
- Boari Flap with Psoas Hitch
- Trans Ureteroureterostomy
- Renal Autotransplantation
- Upper Tract Reconstruction Principles
References
1. Ali-el-Dein B, Ghoneim MA. Bridging long ureteral defects using the Yang-Monti principle. J Urol. 2003;169(3):1074–1077. doi:10.1097/01.ju.0000050151.66653.cc
2. Xiong S, Zhu W, Li X, et al. Intestinal interposition for complex ureteral reconstruction: a comprehensive review. Int J Urol. 2020;27(5):377–386. doi:10.1111/iju.14222
3. Castellan M, Gosalbez R. Ureteral replacement using the Yang-Monti principle: long-term follow-up. Urology. 2006;67(3):476–479. doi:10.1016/j.urology.2005.09.005
4. Ordorica R, Wiegand LR, Webster JC, Lockhart JL. Ureteral replacement and onlay repair with reconfigured intestinal segments. J Urol. 2014;191(5):1301–1306. doi:10.1016/j.juro.2013.11.027
5. Ali-El-Dein B, El-Hefnawy AS, D'Elia G, et al. Long-term outcome of Yang-Monti ileal replacement of the ureter: a technique suitable for mild, moderate loss of kidney function and solitary kidney. Urology. 2021;152:153–159. doi:10.1016/j.urology.2020.09.061
6. Launer BM, Redger KD, Koslov DS, et al. Long-term follow up of ileal ureteral replacement for complex ureteral strictures: single institution study. Urology. 2021;157:257–262. doi:10.1016/j.urology.2021.07.012
7. Liu D, Zhou H, Hao X, et al. Laparoscopic Yang-Monti ureteral reconstruction in children. Urology. 2018;118:177–182. doi:10.1016/j.urology.2018.04.034
8. Kocot A, Kalogirou C, Vergho D, Riedmiller H. Long-term results of ileal ureteric replacement: a 25-year single-centre experience. BJU Int. 2017;120(2):273–279. doi:10.1111/bju.13825
9. Shokeir AA, Gaballah MA, Ashamallah AA, Ghoneim MA. Optimization of replacement of the ureter by ileum. J Urol. 1991;146(2):306–310. doi:10.1016/s0022-5347(17)37777-7
10. Roth JD, Monn MF, Szymanski KM, Bihrle R, Mellon MJ. Ureteral reconstruction with ileum: long-term follow-up of renal function. Urology. 2017;104:225–229. doi:10.1016/j.urology.2017.02.026