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 avoiding the complications of incorporating intestinal mucosa into the urinary tract — metabolic disturbances, mucus production, stones, perforation, and malignancy risk.[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 muscular scaffold that prevents 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.
- Histology confirmed transitional epithelium (urothelium) lining the serosal surface of the bowel patch.
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 studies established that preservation of the intestinal submucosa is essential to prevent patch contraction — the key technical point distinguishing SCLU from earlier failed attempts at demucosalized enterocystoplasty.[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.
- Mucosa stripped from the colonic segment while preserving the submucosa and muscularis mucosae on the seromuscular patch — the most technically demanding step; the dissection plane must be between the mucosa and muscularis mucosae.
Step 3 — Composite anastomosis
- Demucosalized colonic patch placed over the prolapsed urothelium with the serosal surface facing the urothelium.
- Edges of the seromuscular patch sutured to the edges of the detrusor defect.
- Urothelium gradually migrates and lines the inner surface of the seromuscular patch.
Step 4 — Concomitant procedures
- AUS is frequently implanted simultaneously or has been placed previously — a critical component of success (see below).
- 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 requiring simultaneous AUS implantation — SCLU is particularly well-suited.[5][7]
Critical Prerequisites for Success
1. Adequate bladder outlet resistance
The most important determinant: constant high bladder outlet pressure to facilitate adhesion of the bladder mucosa to the seromuscular patch. Jung 2012 (n=33, mean 6.0 yr):[6]
- ALPP 40–60 cm H₂O with simultaneous anti-incontinence surgery → no failures requiring reoperation.
- ALPP < 40 cm H₂O → high failure rate.
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]
The explanation: a continent catheterizable channel creates a low-pressure leak point in the bladder wall, preventing the sustained intravesical pressure needed for the urothelium to adhere to and line the seromuscular patch.
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.
- The AUS provides the constant outlet resistance necessary for urothelial-seromuscular adhesion.
- SCLU is also the preferred method of augmentation when adverse bladder changes develop after prior AUS implantation.
González concluded that SCLU is most effective in patients who already have an AUS or who undergo simultaneous AUS implantation. Constructing a continent catheterizable channel at the time of SCLU is not recommended due to the high failure rate (60%).[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 | 6.0 yr | 2.96× | 39% off anticholinergics | 0% re-augmentation |
| Shekarriz 2000[8] | 20 (SCLU subset) | 64 mo | — | 95% | Low |
Advantages Over Standard Enterocystoplasty
| Feature | SCLU | Standard Enterocystoplasty |
|---|---|---|
| Metabolic disturbances | None | Hyperchloremic acidosis common |
| Mucus production | Not clinically significant | Significant; irrigations required |
| Bladder perforation | 0% across all series | 3–10% |
| Small-bowel obstruction | 0% across all series | 4.5–7% |
| Bladder stones | Very low (1/20 SCLU in Shekarriz; 2/32 in Jednak) | 5–21% |
| Malignancy risk | Theoretically eliminated (urothelial lining) | 1.5–5.5% (latency ~20 yr) |
| Capacity increase | 1.8–2.96× | 2–3× |
| Surgical complexity | Higher (demucosalization + detrusorectomy) | Standard |
Shekarriz directly compared SCLU vs ileocystoplasty vs conventional colocystoplasty in 133 patients and concluded: "SCLU has a low rate of surgical complications and no incidence of perforation or SBO thus far; therefore, we advocate the use of SCLU when feasible, and sigmoid as the preferred bowel segment for augmentation cystoplasty."[8]
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 initial series showed urothelium in 7/10 (70%) with only 2 showing colonic regrowth. The discrepancy likely relates to depth of demucosalization — Dewan demonstrated that removal of the muscularis mucosae and inner submucosa is necessary to prevent regrowth; when these layers are preserved, regrowth occurs in 80%.[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
- Best for patients with adequate or surgically achievable bladder outlet resistance (ideally with simultaneous or pre-existing AUS).[5][6][7]
- Best in those with intact bladder mucosa without prior surgical injury.[6]
- Not recommended when a continent catheterizable channel is to be constructed at the same operation.[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