Seromuscular Colocystoplasty Lined With Urothelium (SCLU)
Seromuscular colocystoplasty lined with urothelium (SCLU) is a form of augmentation cystoplasty that uses a demucosalized colonic segment placed over an autoaugmented bladder, allowing the native urothelium to line the augmented reservoir while the colonic seromuscular layer provides structural support. Developed by González and colleagues in the early 1990s, SCLU was designed to achieve the capacity and compliance benefits of enterocystoplasty while aiming to reduce bowel-mucosa-related metabolic exchange and mucus. Stones, perforation, bowel complications, and malignancy cannot be assumed to be eliminated.[1][2]
Concept and Rationale
Standard enterocystoplasty's central problem is intestinal mucosa in contact with urine — metabolic derangements, mucus, stones, long-term malignancy risk. Earlier attempts to simply strip mucosa from bowel and use the seromuscular layer caused fibrosis and contraction. SCLU combines two principles to solve this:[1]
- Detrusorectomy (autoaugmentation): detrusor excised from the dome, exposing the underlying urothelium, which prolapses outward.
- Seromuscular colonic patch: demucosalized sigmoid colon placed over the prolapsed urothelium — provides a supporting layer intended to reduce urothelial retraction and fibrosis.
The result is a composite augmentation: luminal surface is urothelium (from native bladder); outer wall is colonic seromuscular tissue.[1][2]
Experimental Foundation
The canine model (Buson, González 1994) established critical findings:[1]
- When the intestinal submucosa was preserved on the seromuscular patch → no fibrosis, capacity preserved.
- When the submucosa was not preserved → moderate contraction with subepithelial fibrosis, capacity loss.
- In animals with previously reduced bladder capacity, SCLU effectively augmented.
- Seromuscular patches remained viable and well-vascularized.
- Native bladder urothelium and lamina propria were preserved beneath the patch. This differs from earlier rat experiments that used the serosal surface as a luminal lining.
The earlier rat model (de Badiola 1991) showed seromuscular colonic patches acquire a transitional epithelial lining as early as 5 days postoperatively, with no fibrosis, inflammation, or shrinkage.[3]
These animal studies supported preserving submucosa in the original SCLU technique. Other demucosalized constructs use different dissection planes to reduce mucosal regrowth; their steps should not be combined into a single presumed standard operation.[1]
Surgical Technique
Step 1 — Detrusorectomy
A generous detrusorectomy over the bladder dome, excising the detrusor muscle while preserving the underlying urothelium and lamina propria. The urothelium prolapses through the muscular defect, creating a large epithelial bulge.
Step 2 — Sigmoid colon harvest and demucosalization
- 15–20 cm of sigmoid colon isolated on its vascular pedicle.
- Bowel continuity restored by primary anastomosis.
- Colonic segment detubularized along its antimesenteric border.
- The original SCLU method preserves intestinal submucosa and muscularis mucosae while removing the epithelial lining. Demucosalization depth is technique-specific: deeper removal has been studied to reduce residual crypt regrowth, but may affect patch integrity. Confirm the selected technique rather than merging conflicting dissection planes.
Step 3 — Composite anastomosis
- The vascularized patch supports the exposed native urothelium. The original operative description should determine patch orientation; the serosa-as-lumen rat experiment is not an instruction to invert a clinical SCLU patch.
- Edges of the seromuscular patch sutured to the edges of the detrusor defect.
- Preserve and appose the native urothelial layer; mucosal injury or separation can compromise the construct.
Step 4 — Concomitant procedures
- AUS is frequently implanted simultaneously or has been placed previously — one selected outlet strategy, not a universal requirement.
- Bladder-neck procedures or slings as needed.
Avoiding hourglass deformity[5]
- Early in the experience, hourglass deformity developed in 22% of patients.[4]
- Addressed by ensuring the seromuscular patch is sutured well below the level of the detrusorectomy edge, creating a wider anastomosis.
- Modifications largely eliminated this complication in later series.
Indications
SCLU shares the general indications for augmentation but is specifically considered when the surgeon wishes to avoid incorporating intestinal mucosa into the urinary tract:[2][6][7]
- Neurogenic bladder (myelomeningocele, SCI) with low compliance and/or overactivity refractory to conservative management.
- Bladder exstrophy and cloacal exstrophy.
- Posterior urethral valves.
- Renal insufficiency — where metabolic acidosis from standard enterocystoplasty would be poorly tolerated.
- Patients with combined reservoir and outlet dysfunction; small series describe SCLU with an AUS, without establishing superiority over alternative reconstructions.[5][7]
Critical Prerequisites for Success
1. Adequate bladder outlet resistance
Selected series associate adequate outlet resistance with maintained patch apposition. Abdominal leak point pressure (ALPP) is not storage detrusor pressure, and these findings do not justify maintaining an unsafe high-pressure reservoir. Jung 2012 retrospectively evaluated 33 patients over mean six years:[6]
- Among 17 patients with simultaneous anti-incontinence surgery, none in the ALPP 40–60 cm H₂O group required further surgery.
- Four of ten with ALPP below 40 cm H₂O required additional surgery. This is not a reported augmentation-failure rate or a validated universal pressure threshold.
González confirmed this principle: in 15 patients undergoing SCLU without concomitant bladder procedures (most had an AUS), there were no failures — capacity ↑ from 60% to 100% of expected for age. By contrast, 3/5 patients who underwent creation of a continent catheterizable channel at the time of SCLU required repeat augmentation.[7]
Concomitant bladder surgery may disturb the reconstruction, but this small study cannot establish that mechanism. A functioning continent channel is designed to resist leakage; it should not be described as inherently creating a low-pressure leak point. The small comparison cannot isolate the mechanism.
2. Intact bladder mucosa
SCLU should be primarily considered in patients without prior bladder mucosal injury — previous surgery that has damaged the urothelium may compromise its ability to prolapse and line the seromuscular patch.[6]
Synergistic Role of the AUS
González 2002 in 27 children specifically combined SCLU with AUS:[5]
- 89% (24/27) achieved continence with no additional procedures.
- Bladder capacity, safe capacity for age, and end-filling pressure all improved significantly.
- No significant upper-tract changes.
- Outlet resistance may support patch apposition, but the study does not prove AUS is necessary for adhesion.
- The authors favored SCLU for selected patients with adverse storage changes after AUS; this is a center-specific conclusion.
González concluded that SCLU is most effective in patients who already have an AUS or who undergo simultaneous AUS implantation. The 2009 authors advised against a simultaneous catheterizable channel after three failures among five patients. This small-series caution is specific to SCLU, not to other augmentation techniques.[7]
Outcomes
| Series | n | Follow-up | Capacity ↑ | Continence | Failure |
|---|---|---|---|---|---|
| González 1995[2] | 16 | 12 mo | 2.4× (139 → 335 mL) | 81% | 12.5% |
| Jednak 2000[4] | 32 | 1.6 yr | 1.8× (total) / 2.4× (safe) | 71→81% | 12.5% |
| González (with AUS) 2002[5] | 27 | 1.7 yr | Significant | 89% | 3.7% |
| González 2009[7] | 20 | 53 mo | 60 → 100% expected for age | 100% (Group 1, no channel) | 0% G1 / 60% G2 (with channel) |
| Jung 2012[6] | 33 | Mean 6.0 yr | 2.96× | 13/33 stopped anticholinergics; not a continence rate | Additional outlet surgery occurred; see subgroup results above |
| Shekarriz 2000[8] | 20 SCLU within 133 mixed augmentations | Mean 64 mo across whole cohort | — | 95% refers to the whole mixed cohort | No SCLU perforation or SBO observed |
Evidence Compared with Standard Enterocystoplasty
| Feature | SCLU | Standard Enterocystoplasty |
|---|---|---|
| Metabolic disturbances | Reduced bowel-mucosa exposure; none reported in selected small series | Metabolic exchange requires monitoring |
| Mucus production | Not clinically significant | Significant; irrigations required |
| Bladder perforation | None observed in cited small cohorts; risk is not proven zero | Recognized long-term risk varying by population |
| Bowel obstruction | None observed in selected cohorts; bowel surgery still carries risk | Recognized bowel and adhesion morbidity |
| Bladder stones | Very low (1/20 SCLU in Shekarriz; 2/32 in Jednak) | 5–21% |
| Malignancy risk | Not eliminated; baseline disease and possible intestinal regrowth remain relevant | Long-latency risk; estimates depend on population and follow-up |
| Capacity increase | 1.8–2.96× | 2–3× |
| Surgical complexity | Higher (demucosalization + detrusorectomy) | Standard |
Shekarriz’s retrospective 133-patient comparison included only 20 SCLU patients; none had perforation or SBO during that follow-up. Its authors favored SCLU/sigmoid, but this does not establish superiority.[8] A separate retrospective comparison of 26 SCLU versus 32 conventional augmentations found no statistically significant differences in capacity, continence, or several reoperation outcomes. Both groups remained at risk of stones, reflux, and augmentation failure.[10]
Complications
- Hourglass deformity — the most characteristic complication; ~22% (7/32 in Jednak; 6/27 in González AUS series). Technical modifications (suturing the patch well below the detrusorectomy edge) have largely eliminated this in later series.[4][5]
- Colonic mucosal regrowth — a significant concern. Jednak biopsies showed regrowth in 5/7 (71%); González’s initial series showed urothelium alone in 7/10 biopsies, colonic regrowth in two, and mixed urothelium/colonic mucosa in one. Dewan found regrowth in 4/5 sheep with preserved muscularis mucosae/submucosa, compared with none after deeper removal; ten clinical patients had no detected regrowth. This is not an 80% human risk or proof of one universally safe dissection plane.[2][4][9]
- Augmentation failure requiring re-augmentation — 0–12.5% depending on series and patient selection; highest failure rates occur when SCLU is combined with continent catheterizable channel construction (60% in González 2009 Group 2).[7]
Patient Selection Summary
- Consider selected patients with adequate or surgically achievable outlet resistance, safe storage pressures, and a dependable catheterization route; AUS is one option.[5][6][7]
- Best in those with intact bladder mucosa without prior surgical injury.[6]
- Discuss the limited SCLU-specific evidence suggesting increased failure with simultaneous channel construction; avoid presenting the five-patient subgroup as a universal contraindication.[7]
- Particularly attractive in renal insufficiency where standard enterocystoplasty acidosis would be poorly tolerated.
References
1. Buson H, Manivel JC, Dayanç M, Long R, Gonzalez R. "Seromuscular Colocystoplasty Lined With Urothelium: Experimental Study." Urology. 1994;44(5):743-8. doi:10.1016/s0090-4295(94)80220-3
2. Gonzalez R, Buson H, Reid C, Reinberg Y. "Seromuscular Colocystoplasty Lined With Urothelium: Experience With 16 Patients." Urology. 1995;45(1):124-9. doi:10.1016/s0090-4295(95)97364-8
3. de Badiola F, Manivel JC, Gonzalez R. "Seromuscular Enterocystoplasty in Rats." The Journal of Urology. 1991;146(2 Pt 2):559-62. doi:10.1016/s0022-5347(17)37854-0
4. Jednak R, Schimke CM, Barroso U Jr, Barthold JS, González R. "Further Experience With Seromuscular Colocystoplasty Lined With Urothelium." The Journal of Urology. 2000;164(6):2045-9.
5. González R, Jednak R, Franc-Guimond J, Schimke CM. "Treating Neuropathic Incontinence in Children With Seromuscular Colocystoplasty and an Artificial Urinary Sphincter." BJU International. 2002;90(9):909-11. doi:10.1046/j.1464-410x.2002.03036.x
6. Jung HJ, Lee H, Im YJ, et al. "Prerequisite for Successful Surgical Outcome in Urothelium Lined Seromuscular Colocystoplasty." The Journal of Urology. 2012;187(4):1416-21. doi:10.1016/j.juro.2011.12.009
7. González R, Ludwikowski B, Horst M. "Determinants of Success and Failure of Seromuscular Colocystoplasty Lined With Urothelium." The Journal of Urology. 2009;182(4 Suppl):1781-4. doi:10.1016/j.juro.2009.02.062
8. Shekarriz B, Upadhyay J, Demirbilek S, Barthold JS, González R. "Surgical Complications of Bladder Augmentation: Comparison Between Various Enterocystoplasties in 133 Patients." Urology. 2000;55(1):123-8. doi:10.1016/s0090-4295(99)00443-4
9. Dewan PA, Close CE, Byard RW, Ashwood PJ, Mitchell ME. "Enteric Mucosal Regrowth After Bladder Augmentation Using Demucosalized Gut Segments." The Journal of Urology. 1997;158(3 Pt 2):1141-6. doi:10.1097/00005392-199709000-00114
10. Bandi G, Al-Omar O, McLorie GA. Comparison of traditional enterocystoplasty and seromuscular colocystoplasty lined with urothelium. J Pediatr Urol. 2007. doi:10.1016/j.jpurol.2007.04.004.