Intestinal Segments
Bowel segments (ileum, sigmoid, ileocecal) used in urinary tract reconstruction leverage intestinal mucosal properties, bulk availability, and native blood supply. Transferred as vascularized pedicle (not a graft in the strictest sense) but included here as a tissue-substitution resource.
See the overview article for the reference summary: Grafts in GU Reconstruction, and the anatomy article: Bowel Anatomy. Bowel anastomosis technique is covered in Bowel Anastomosis. For segment selection when a prior bowel anastomosis or resection already exists, see Reoperative Bowel Harvest.
Core Principle
Intestinal segments are not free grafts in the strict technical sense; they are vascularized visceral segments isolated on a mesenteric pedicle and repurposed as reservoir, conduit, channel, or lining. They are included in the grafts library because the reconstructive question is the same: which tissue best substitutes for the missing urinary or genital surface?
The tradeoff is predictable. Bowel provides length, compliance, bulk, and a reliable blood supply, but it remains bowel: it secretes mucus, absorbs and exchanges electrolytes, hosts bacteria, peristalses unless detubularized, and creates lifelong surveillance obligations.[1][2]
Ileum
The ileum is the default bowel segment for most urinary reconstruction because it is mobile, easy to isolate on a dependable SMA-based mesentery, and behaves well after detubularization.[1][3]
| Property | Reconstructive implication |
|---|---|
| Long mesentery and multiple arcades | Reliable reach into the pelvis for conduit, neobladder, or augmentation |
| Thin wall and good compliance after detubularization | Useful for low-pressure reservoirs |
| Mucus production | Requires irrigation education in catheterized reservoirs |
| Terminal ileum absorbs B12 and bile salts | Preserve the most distal ileum when possible; monitor B12 after meaningful ileal loss |
Applications
- Ileocystoplasty and broader augmentation cystoplasty
- Orthotopic neobladder families such as Hautmann neobladder and modified Studer pouch
- Ileal conduit
- Ileal ureter and Yang-Monti ileal ureter
- Yang-Monti catheterizable channel
Sigmoid Colon
Sigmoid colon offers a larger caliber, thicker wall, and IMA-based pedicle. It is useful when ileum is unavailable or when a self-lubricating vaginal substitute is desired, but colonic urine contact can produce pronounced mucus and hyperchloremic acidosis.[1][2]
| Property | Reconstructive implication |
|---|---|
| Larger caliber and thicker wall | Useful for reservoirs and neovagina, but can be bulky in a narrow pelvis |
| IMA / sigmoid-artery pedicle | Requires attention to marginal artery and rectosigmoid watershed perfusion |
| High mucus output | Irrigation and stone prevention matter |
| Colonic chloride / ammonium handling | Higher vigilance for hyperchloremic metabolic acidosis |
Applications
- Sigmoid cystoplasty
- Sigmoid neovagina / bowel vaginoplasty when skin-graft or peritoneal options are unsuitable
- Colon conduit or colon shuffle when ileum is unusable
Ileocecal Segment
The ileocecal segment combines terminal ileum, cecum, appendix, and right-colon territory. Its special value is that the ileocecal valve and appendix can be incorporated into continent cutaneous systems, while the right colon supplies reservoir capacity.[1][4]
| Component | Reconstructive role |
|---|---|
| Cecum / right colon | Reservoir wall for continent cutaneous diversion or augmentation |
| Terminal ileum | Catheterizable limb, efferent limb, or reconfigured channel |
| Ileocecal valve | Historical continence / antireflux logic in ileocecal reservoirs |
| Appendix | Natural small-caliber catheterizable channel when present and usable |
Applications
- Ileocecal cystoplasty
- Indiana pouch
- Appendicovesicostomy / Mitrofanoff
- Ileocecal continent cutaneous diversion families, including Mainz / right-colon variants
Metabolic Complications
Every bowel-urine interface creates a chronic absorptive and secretory system. The segment determines the dominant abnormality, but the surveillance principle is universal: renal function, electrolytes, acid-base status, B12 when ileum is used, stones, infections, and late malignancy risk require long-term follow-up.[2][5]
| Issue | Most relevant segments | Practical response |
|---|---|---|
| Hyperchloremic metabolic acidosis | Ileum and colon | Monitor bicarbonate / chloride; treat with oral alkali when clinically significant |
| Mucus production | All intestinal segments, especially colon | Teach irrigation for catheterized reservoirs; evaluate stones and recurrent blockage |
| Vitamin B12 deficiency | Terminal ileum | Preserve terminal ileum when possible; monitor and supplement B12 |
| Bile-salt malabsorption | Terminal ileum | Watch for diarrhea and fat-soluble vitamin issues after longer resections |
| Stones and chronic bacteriuria | Reservoirs and catheterizable systems | Hydration, complete emptying, mucus management, targeted infection treatment |
| Late malignancy | Augmented bladders and bowel reservoirs | Symptom-triggered endoscopy; individualized long-term surveillance |
For the dedicated management pages, see Renal Function & Metabolic Surveillance, Mucus Management, Vitamin B12 Supplementation, and Urinary Acidifiers & Alkalinizers.
References
1. Santucci NR, Velez A. "Physiology of Lower Gastrointestinal Tract." Aliment Pharmacol Ther. 2024;60 Suppl 1:S1-S19. doi:10.1111/apt.17900
2. Kiela PR, Ghishan FK. "Physiology of Intestinal Absorption and Secretion." Best Pract Res Clin Gastroenterol. 2016;30(2):145-159. doi:10.1016/j.bpg.2016.02.007
3. Khoury AE, Salomon M, Doche R, et al. "Stone formation after augmentation cystoplasty: the role of intestinal mucus." J Urol. 1997;158(3 Pt 2):1133-1137. doi:10.1016/S0022-5347(01)64400-3
4. Rowland RG, Mitchell ME, Bihrle R, Kahnoski RJ, Piser JE. "Indiana continent urinary reservoir." J Urol. 1987;137(6):1136-1139. doi:10.1016/S0022-5347(17)44409-6
5. Stabler SP. "Vitamin B12 Deficiency." N Engl J Med. 2013;368(2):149-160. doi:10.1056/NEJMcp1113996