Penn Pouch
The Penn Pouch is a continent cutaneous urinary diversion that uses the ileocecal segment (cecum and terminal ileum) to create a reservoir, grouped with the family of ileocecal continent pouches alongside the Indiana, Mainz, and King pouches.[1] Developed at the University of Pennsylvania in the mid-1980s, it is among the less extensively documented of the major named pouches, with limited dedicated published series compared to the Indiana or Mainz Pouch I. Its defining feature is the use of the intussuscepted ileocecal valve as the continence mechanism — stabilized with staples and historically a Marlex (polypropylene) collar.
Historical Context and Classification
The Penn Pouch derives its name from the University of Pennsylvania and was developed during the period of rapid innovation in continent urinary diversion in the mid-1980s. It belongs to the family of ileocecal continent cutaneous diversions.[1]
In the 1988 Amis, Newhouse, and Olsson Radiology review, the Penn Pouch was listed alongside the Indiana, Mainz, and King techniques as one of the four principal ileocecal continent diversions of the era, all sharing the common feature of combining cecum and terminal ileum to construct the reservoir.[1]
| Pouch | Institution | Reservoir | Continence Mechanism | Distinguishing Feature |
|---|---|---|---|---|
| Penn Pouch | University of Pennsylvania | Cecum ± ileal augmentation | Intussuscepted ileocecal valve | Stapled intussusception + Marlex collar |
| Indiana Pouch | Indiana University | Detubularized right colon + terminal ileum | Plicated/tapered terminal ileum | Simplicity; no intussusception |
| Mainz Pouch I | University of Mainz | Detubularized cecum + 2 ileal loops | Appendix or intussuscepted ileal nipple | Most versatile; largest series |
| King Pouch | King's College, London | Ileocecal segment | Intussuscepted ileocecal valve | Similar to Penn concept |
Design Principles
The Penn Pouch shares the fundamental design principles of all ileocecal continent diversions.[1][2][3][4]
- Cecal reservoir — the cecum (with or without detubularization) serves as the primary reservoir, exploiting its natural capaciousness and distensibility.
- Intussuscepted ileocecal valve as continence mechanism — the defining feature of the Penn Pouch (shared with the King Pouch and the closely related Webster/Bertram technique). The native ileocecal valve is intussuscepted and stabilized to create a continent catheterizable nipple. This differs from the Indiana Pouch (plication of the terminal ileum) and the Mainz Pouch I (appendix or intussuscepted ileal nipple).[2][4]
- Antireflux ureteral reimplantation — submucosal tunnels into the cecal wall, exploiting the thick colonic wall.
Why intussuscept the ileocecal valve?[2][4] The valve is a natural sphincteric structure. Intussuscepting it converts the valve into a nipple-like structure protruding into the cecal reservoir, creating a one-way valve that prevents urine leakage while allowing easy catheter passage. The intussusception was stabilized with staples and reinforced with a Marlex (polypropylene) collar to prevent dessusception — a technique closely related to and contemporaneous with Webster and Bertram's 1986 description.
Surgical Technique
Based on the Webster / Bertram description and the Lowe / Woodside urodynamic evaluations.[2][4]
- Bowel isolation — ~ 10–15 cm of terminal ileum + the cecum / ascending colon, preserving the ileocolic vascular pedicle and the ileocecal valve.
- Bowel continuity — ileoascending colonic anastomosis.
- Reservoir construction — the cecum serves as the reservoir. In some variations the cecum is left intact (not detubularized); when so, it tends to be hyperactive with high-amplitude contractions, often requiring anticholinergic medication.[2]
- Intussusception of the ileocecal valve — the terminal ileum is intussuscepted through the ileocecal valve into the cecal lumen, stapled (GIA or TA) to prevent dessusception, and reinforced with a Marlex (polypropylene) collar at the base. The distal ileum is brought to the skin as a flush catheterizable stoma.[2]
- Ureteral reimplantation — antireflux submucosal tunnels into the cecal wall.
- Bladder-augmentation variant — in some patients the Penn Pouch concept was applied as a bladder augmentation: the bladder neck was closed, the native bladder augmented with the cecal segment, and the intussuscepted ileocecal valve served as the continent catheterizable stoma.[2]
Functional Outcomes and Urodynamics
Webster and Bertram 1986 (n = 7)
- 3 patients: bladder augmentation with continent stoma (bladder neck closed)
- 4 patients: isolated cecal reservoir replacing the bladder
- All 7 had satisfactory capacity and a continent stoma without significant catheterization difficulties
- Cecal hyperactivity controlled with anticholinergic medication.[2]
Lowe and Woodside 1990 — Urodynamic Evaluation (n = 5)
| Parameter | Result |
|---|---|
| Incontinence | Minimal — related only to prolonged catheterization interval |
| Passive filling pressure | Low in all patients |
| Peristaltic pressure | Low in all patients |
| Nipple-valve pressure vs reservoir pressure | Nipple > reservoir in 4/5 patients |
| Reflux | None |
| Transient incontinence | 1 patient — reservoir pressure transiently exceeded nipple pressure at capacity; resolved with shortened catheterization interval |
The intussuscepted ileocecal valve generates sufficient resistance to maintain continence under normal filling, though transient pressure spikes at maximum capacity can occasionally exceed nipple pressure.[4]
Comparison — Plicated Ileal Continence Mechanism (Carroll 1989, n = 14)
Carroll's UCSF series used plicated terminal ileum (Indiana-style) rather than intussusception:[3]
| Parameter | Result |
|---|---|
| Continence | 12/14 (86%) completely continent; 2 mild nighttime incontinence |
| Mean reservoir volume | 675 mL |
| Mean reservoir contraction pressure | 24 cm H₂O (max 47) |
| Mean plicated-ileal contraction pressure | 40 cm H₂O (max 151) |
| Reservoir vs plicated-segment pressure | Plicated significantly higher (p = 0.043 mean; p < 0.001 max) |
| Reflux | None |
The plicated ileal segment acts as an effective sphincter that responds to reservoir pressure elevations.[3]
Complications and Limitations
Intussuscepted-Valve Complications
| Complication | Mechanism | Incidence (related series) |
|---|---|---|
| Dessusception (nipple slippage) | Failure of staple / Marlex fixation | 3–5% |
| Stomal stenosis | Ischemia or scarring at skin level | 15–17% |
| Stone formation | Exposed staples as nidus | 3–11% |
| Nipple necrosis | Vascular compromise of intussuscepted segment | 2–4% |
| Cecal hyperactivity | Intact (non-detubularized) cecum | Common |
| Difficult catheterization | Angulation / redundancy of efferent limb | Variable |
Sources: Webster 1986; Lowe 1990; Gerharz 1997.[2][4][5]
Cecal Hyperactivity
A significant limitation of the intact (non-detubularized) cecal reservoir was cecal hyperactivity — high-amplitude peristaltic contractions that could overwhelm the continence mechanism. This was managed with anticholinergic medication but represented a fundamental design limitation, and was a key driver of the evolution toward detubularized ileocecal reservoirs (Indiana, Mainz Pouch I), which disrupted coordinated peristalsis and created lower-pressure, higher-capacity reservoirs.[2][3][4]
The Marlex-Collar Concern
The Marlex (polypropylene mesh) collar introduced a foreign body with potential risks of erosion, stone formation on exposed mesh, infection, and fistula formation. These concerns contributed to the broader move away from intussusception-based continence mechanisms toward simpler alternatives (plication, appendix).[2][5]
Evolution and Relationship to Other Pouches
What the Penn Pouch contributed:
- Demonstrated that the ileocecal valve could be used as a continence mechanism through intussusception.
- Confirmed that the cecal segment could serve as a urinary reservoir with acceptable pressure-volume characteristics.[4]
- Validated antireflux ureteral reimplantation into the thick colonic wall.[1]
Why the Penn Pouch was largely superseded:
- Cecal hyperactivity — solved by detubularization in Indiana and Mainz pouches.[2][3]
- Intussusception complications — dessusception, stone formation on staples, and nipple necrosis. The plicated ileum (Indiana) and appendix (Mainz I) proved simpler and more reliable.[2][5]
- Foreign body (Marlex collar) — additional complication risk; later techniques avoided foreign materials entirely.[2]
- Limited published series — small, single-center cohorts compared to the hundreds of Indiana / Mainz I / Kock patients, limiting evidence base and adoption.[1]
Penn Pouch in the Context of CHOP / Pediatric Reconstruction
The work of Duckett and Lotfi at the Children's Hospital of Philadelphia (also University of Pennsylvania) contributed significantly to pediatric continent reconstruction using the Mitrofanoff principle (appendicovesicostomy). Their 1993 series of 41 pediatric patients showed 100% continence using the appendix, tapered ileum, or ureter as catheterizable channels implanted into bladder remnants or colonic segments.[6] Although distinct from the Penn Pouch, it represents the broader Penn institutional contribution to continent urinary reconstruction and shares the institutional heritage.
Comparison with Other Ileocecal Pouches
| Feature | Penn Pouch | Indiana Pouch | Mainz Pouch I | Kock Pouch |
|---|---|---|---|---|
| Reservoir | Cecum (intact or detubularized) | Detubularized right colon + terminal ileum | Detubularized cecum + 2 ileal loops | Detubularized ileum only |
| Continence mechanism | Intussuscepted ileocecal valve (stapled + Marlex collar) | Plicated/tapered terminal ileum | Appendix or intussuscepted ileal nipple | Intussuscepted efferent nipple |
| Detubularization | Variable (often intact) | Yes | Yes | Yes |
| Foreign material | Yes (Marlex collar, staples) | No (or minimal) | Staples (nipple) or none (appendix) | Staples |
| Cecal hyperactivity | Common (anticholinergics often needed) | Eliminated by detubularization | Eliminated by detubularization | N/A (ileum only) |
| Continence rate | ~ 100% (small series) | 89–100% | 82–92.8% | 84–95% |
| Stone formation | Risk from staples / Marlex | 5.4–19% | 5.6–10.8% | 16.7–44% |
| Reoperation rate | Not well documented | 10.8–22% | 11–36% | 22–53% |
| Series size | Small (~ 7–14 patients) | Hundreds | > 800 | Hundreds |
| Current use | Largely historical | Active | Active | Declining |
Current Status
The Penn Pouch is largely of historical significance in contemporary urological practice. It played an important role in the evolution of ileocecal continent diversions during the 1980s, demonstrating the feasibility of using the intussuscepted ileocecal valve for continence. However, its limitations — particularly cecal hyperactivity, intussusception-related complications, and the need for prosthetic material — led to its replacement by the Indiana Pouch (simpler plication-based continence) and the Mainz Pouch I (appendix-based continence with detubularized reservoir), both validated in much larger, long-term series.[1][2][3][4][5]
The Penn Pouch's legacy lies in its contribution to the understanding that natural anatomical structures (the ileocecal valve) could be exploited for continence, and in the broader Penn / CHOP contribution to pediatric continent reconstruction through the Mitrofanoff principle.[1][6]
Key Takeaways
- The Penn Pouch is a 1980s ileocecal continent cutaneous diversion using the intussuscepted ileocecal valve (stapled and historically reinforced with a Marlex collar) as the continence mechanism.[1][2]
- The cecal reservoir provides acceptable pressure-volume characteristics but the intact (non-detubularized) cecum is prone to hyperactivity requiring anticholinergic medication.[2][4]
- Limited published series (n ≈ 7–14 across related cohorts) and the dominance of detubularized alternatives (Indiana, Mainz I) led the Penn Pouch to be largely supplanted.[1]
- The Marlex collar and stapled intussusception introduced foreign-body risk (erosion, stone formation, fistula) that is avoided in plication-based and appendix-based modern alternatives.[2][5]
- The Penn / CHOP institutional legacy in continent reconstruction is most enduring through the Duckett-Lotfi pediatric Mitrofanoff work.[6]
See Also
References
1. Amis ES, Newhouse JH, Olsson CA. "Continent Urinary Diversions: Review of Current Surgical Procedures and Radiologic Imaging." Radiology. 1988;168(2):395–401. doi:10.1148/radiology.168.2.3293109
2. Webster GD, Bertram RA. "Continent Catheterizable Urinary Diversion Using the Ileocecal Segment With Stapled Intussusception of the Ileocecal Valve." J Urol. 1986;135(3):465–9. doi:10.1016/s0022-5347(17)45693-x
3. Carroll PR, Presti JC, McAninch JW, Tanagho EA. "Functional Characteristics of the Continent Ileocecal Urinary Reservoir: Mechanisms of Urinary Continence." J Urol. 1989;142(4):1032–6. doi:10.1016/s0022-5347(17)38979-6
4. Lowe BA, Woodside JR. "Urodynamic Evaluation of Patients With Continent Urinary Diversion Using Cecal Reservoir and Intussuscepted Ileocecal Valve." Urology. 1990;35(6):544–7. doi:10.1016/0090-4295(90)80114-3
5. Gerharz EW, Köhl U, Weingärtner K, et al. "Complications Related to Different Continence Mechanisms in Ileocecal Reservoirs." J Urol. 1997;158(5):1709–13. doi:10.1016/s0022-5347(01)64105-3
6. Duckett JW, Lotfi AH. "Appendicovesicostomy (And Variations) in Bladder Reconstruction." J Urol. 1993;149(3):567–9. doi:10.1016/s0022-5347(17)36150-5