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Kock Pouch

The cutaneous urinary Kock pouch is a reconfigured ileal reservoir with two intussuscepted nipple valves: an afferent valve intended to prevent reflux toward the ureters and an efferent valve providing resistance at the catheterizable outlet. The orthotopic Kock neobladder retains the afferent valve but connects to the urethra; continence then depends on the urethral outlet rather than a cutaneous nipple.[1][2][3]

This reconstruction contributed substantially to continent urinary diversion. Its historical experience also demonstrates the long-term burden of valve dysfunction, exposed foreign material, stones and repeat surgery.

Historical Development​

Nils Kock devised the continent ileostomy for fecal diversion in 1969, and its intussuscepted nipple valve was a later addition.[31][32] The reservoir was adapted for urinary diversion in 1975; Gerber's 1983 report of seven patients followed up to three years described completely continent reservoirs with two nipple valves, emptied by self-catheterization.[33]

  • 1982. Skinner began the Kock pouch at USC. His modification removed a narrow strip of mesentery for 8 cm along the afferent and efferent limbs so that the ileum could intussuscept adequately, with fixation to prevent reflux and preserve continence. The first 51 patients (August 1982 to January 1984) had one postoperative death and 10 early complications.[1]
  • 1986. USC adapted the reservoir for orthotopic reconstruction, and reported 295 men by 1993.[2] Ghoneim, Kock and colleagues at Mansoura had published the urethral Kock pouch in 1987.[3]
  • 1990s. Late valve problems, exposed staples and eroded nonabsorbable collars led to changes in fixation. Ghoneim's group stabilized the nipple with a mesenteric window and an additional row of staples.[13] After staples were reduced and the Marlex collar eliminated, the reported pouch stone rate in the later USC experience was 10%.[21]
  • 1998. Stein introduced the T pouch to avoid the intussuscepted afferent nipple (see below).[29]

Design Principles​

The cutaneous Kock reservoir uses detubularization to disrupt coordinated peristalsis and spherical reconfiguration to increase capacity at lower pressure, with intussuscepted efferent and afferent valves for continence and reflux prevention.[1] The orthotopic Kock neobladder omits the efferent nipple, whereas the distinct T pouch uses a serosa-lined tunnel in place of the afferent nipple.[3][29] The cutaneous Kock pouch is emptied through its stoma by intermittent self-catheterization without an external collection appliance.[1][7][33] The orthotopic Kock neobladder empties through the urethra; intermittent catheterization is used when residual urine requires it.[3][14]

Selection and Operative Framework​

The AUA/ASCO/ASTRO/SUO guideline lists insufficient bowel length, inability to self-catheterize because of motor or psychological limitations, and inadequate renal or hepatic function as absolute contraindications to continent diversion.[4] Its discussion also groups cancer at the urethral margin and significant uncorrectable urethral stricture disease under that heading; these urethral factors concern eligibility for an orthotopic outlet, whereas the cutaneous Kock pouch drains through a stoma.[4][37] The EAU lists debilitating neurologic or psychiatric illness, limited life expectancy, and severe renal or hepatic impairment as contraindications to continent diversion. For orthotopic neobladder after cancer surgery, it permits consideration in selected N1 disease but not N2 or N3 disease.[37] It identifies high-dose preoperative radiotherapy, complex urethral stricture, and severe sphincter-related incontinence as relative contraindications to orthotopic neobladder.[37] Candidates must also be able to maintain follow-up. An orthotopic reservoir requires an appropriate retained urethra; in cancer surgery, AUA/ASCO/ASTRO/SUO Statement 14 calls for verification of a negative urethral margin, with pathologic assessment at surgery described as best practice.[4] AUA discusses an eGFR below 45 as an example of inadequate renal function for continent diversion.[4]

ComponentCutaneous Kock pouchOrthotopic Kock neobladder
ReservoirDetubularized ileum reconfigured for compliant storageReconfigured ileal reservoir
Ureteral drainageUreters enter an afferent ileal segment proximal to its nipple valveAfferent ileal segment with antireflux nipple
OutletEfferent intussuscepted valve and abdominal stomaReservoir-to-urethra anastomosis; no cutaneous efferent valve
EmptyingIntermittent catheterizationPelvic-floor relaxation with abdominal pressure; catheterization if required for safe emptying

The operative sequence comprises vascular assessment and bowel isolation, restoration of intestinal continuity, reservoir reconfiguration, valve construction, ureteral implantation, outlet creation and secure drainage. Preserve perfusion during any mesenteric window or intussusception and avoid tension, kinking or outlet obstruction.[1][5][3] The early Skinner modification described mesenteric stripping and fixation to stabilize the valves.[1][5][3]

Historical nonabsorbable collars caused erosion and obstruction. Arai's 42-patient series identified 10 late afferent complications, including collar erosion, stenosis and obstruction by mucus or a fungus ball; the construction and its modifications must be specified when comparing outcomes.[6]

Detubularization reduces coordinated contractions. Neither a reported maximum capacity of 1,400 mL nor a fixed catheterization interval is a treatment target. In the early 51-patient USC series, patients catheterized every 4–6 hours by day and once at night; current intervals should follow measured volumes, continence, pressure and emptying.[1]

Historical Outcomes: Preserve the Denominators​

Cutaneous reservoirs​

ReportPopulation and follow-upUseful result and limitation
Skinner 1987[7]250 patients; procedures 1982–198577 patients underwent 85 revisions for late complications; the comparison was not randomized
Skinner 1988[5]531 overall; late cutaneous outcomes analyzed in 489Late complications fell to 22% after a 1985 technical modification
Chen 1990[8]53 patients; 6–39 months45 had good continence; 4 had valve prolapse and 4 poor continence requiring more frequent catheterization
Henriet 1991[9]135 mixed reconstructions: 72 cutaneous, 45 urethral, 10 ileorectal and 8 hemi-Kock augmentation cystoplasty94.2% cutaneous continence; late complications after the cutaneous pouch were 26.1% with the Kock-Skinner technique and 7.4% with a simplified technique
Arai 1993[10]76 Kock/39 Indiana operated; 68/37 followed at least 12 months, mean 53/34 monthsEarly complications 18.4% versus 17.9%. Revisions 15/68 versus 4/37; stones 18/68 versus 2/37. Longer Kock follow-up and historical collars complicate comparison
Okada 1996[11]102 Kock/61 Indiana operated; 95/59 followed beyond 3 months, mean 83/50 monthsKock open repair 36/95 and stones 42/95; “approximately 90% success” was not a 90% complete-continence rate

These reports overlap in centers and operative eras.

Orthotopic reservoirs​

ReportPopulationReported function
Ghoneim 1987[3]16 men; 3–9 monthsAll continent by day; 4 had nocturnal enuresis
Kock 1989[12]43 men; 34 functionally evaluable, mean 13 months30/34 continent day and night; 18/43 developed reflux after afferent-valve eversion/sliding, and 16/18 also became incontinent. Surgical correction restored reflux prevention and continence in the treated cases
Ghoneim 1992[13]185 operated; 117 fully evaluable beyond 1 year108/117 completely continent by day and 85/117 dry at night; 24 renal units deteriorated (16 with reflux, 8 with anastomotic stricture)
Stein 1997[36]34 women; 33 evaluable, median 30 months29/33 (88%) completely continent by day and 27/33 (82%) at night; 5 (15%) needed some intermittent catheterization
Elmajian 1996[2]295 men87% daytime and 86% nighttime good or satisfactory continence; 5% regular catheterization.
Steven 2000[14]166 men; serial follow-upHigh reported continence coexisted with nighttime protection and increasing catheterization requirements

In Steven's cohort, reported nighttime continence rose from 75% at one year to 94% at five years, but only 39.8% used no nighttime protection at one year and 45.9% at three years. Intermittent catheterization for residuals above 100 mL rose from 16% at six months to 44% at five years. The reported five-year risks were 34% for stones and 33% for B12 deficiency.[14]

Stein's updated series of the Kock ileal neobladder in women included 34 patients aged 31 to 86 years (median 67), most after cystectomy for transitional cell carcinoma and one undiversion to the native urethra. There were 4 early (11%) and 3 late (9%) complications; 28 of the 33 evaluable women voided to completion, and 5 used intermittent catheterization to empty the reservoir.[36]

Urodynamics and Emptying​

In Chen's 20-patient cutaneous study, five had pressure spikes. Their mean maximal pouch pressure was 41 cm H₂O, compared with 11.6 cm H₂O in those without spikes. Mean functional pouch capacity was 332.7 mL without spikes and 280 mL with spikes. Mean maximal nipple pressure was 72.1 cm H₂O, mean maximal nipple closure pressure 58.8 cm H₂O and mean functional nipple length 3.4 cm. In five patients, a functional nipple length of 2.5 cm or less and/or a closure pressure below 40 cm H₂O correlated with a capacity below 200 mL and with frequent catheterization for continence, whereas closure pressure above 60 cm H₂O and nipple length above 3.0 cm correlated with capacity above 350 mL.[15]

Gotoh's 18-man orthotopic study found a mean storage pressure of 33.2 cm H₂O and voiding pressure of 77.3 cm H₂O; eight had voiding pressures of 80–150 cm H₂O. One patient with reflux during high-pressure emptying started catheterization. A reservoir that stores adequately may still empty at excessive pressure: evaluate obstruction, residual volume and upper-tract changes.[16]

Valve Dysfunction and Stones​

Afferent obstruction​

The 802-patient USC report identified 79 patients with 84 afferent-valve complications: 42 stone events on staples, 35 stenoses and 7 prolapses.[17]

A normal pouch contrast study does not exclude upstream obstruction. In Stein's 13-patient stenosis series, functional kidneys were hydronephrotic despite uniformly normal pouch radiographs. Seven patients needed a single dilation; six needed repeat dilation and four of those proceeded to open revision.[18]

Late problems can occur decades after construction. Locke's seven-case series had a median 17 years from diversion to valve intervention. All underwent upper-tract imaging and nephrostomy drainage; six ultimately had surgical repair and one had successful antegrade dilation.[19]

Outlet problems​

Incontinence, difficult catheterization, valve prolapse, fistula and false passage require assessment of the actual outlet and reservoir. Repeated traumatic catheter attempts can worsen access. Inability to drain the reservoir warrants prompt urologic assessment; a nine-patient cutaneous Kock pouch series described two extraperitoneal ruptures in one patient after delayed catheterization.[38] Arai's long-term group had nine efferent malfunctions among 68 Kock patients, five requiring revision.[10]

Carr's sequential single-surgeon comparison found revisions in 16/30 Kock versus 4/30 right-colon patients. Median follow-up was 50 versus 16 months, and age and disease indications differed.[20]

Stones​

Ginsberg reported stones in 64/383 cutaneous reservoirs, often associated with exposed staples or eroded Marlex; 13 patients had recurrence. Terai's later comparison found stones in 31/72 Kock versus 7/54 Indiana pouches, with five-year stone-free estimates of 66% versus 84%. Construction era, infection, metabolic factors, irrigation and follow-up all affect interpretation.[21][22]

Plan stone access to protect the continence mechanism. EAU notes that endoscopy through a continent channel can damage it; percutaneous or open access is often preferred. EAU makes a weak recommendation for regular saline irrigation to reduce stone recurrence in patients with bladder augmentation, a continent cutaneous urinary reservoir, or neuropathic bladder dysfunction who have no history of autonomic dysreflexia; tailor the regimen and teach it safely.[23]

Metabolic Surveillance​

Vitamin B12 malabsorption and low serum B12 are different outcomes. In Pannek's study, Schilling-test absorption was reduced in 20/25 Kock patients versus 0/29 other ileal neobladders at mean 13 months, yet four in each group had low serum B12.[24] The proposed 50 cm ileal threshold was an inference from that study.[24]

Terai found malabsorption in 3/9 tested Kock patients and 4/6 tested Indiana patients, while no patient in the larger serum-level cohorts had B12 below 200 pg/mL. Neither the 33% Kock malabsorption proportion nor the 67% Indiana malabsorption proportion is a rate of clinical B12 deficiency.[25] In a 20-patient pediatric/adolescent series followed 5–12 years, two developed subnormal B12; renal dysfunction also complicated interpretation of methylmalonic acid.[26]

Monitor renal function, bicarbonate/electrolytes and nutritional status. The EAU bladder cancer guideline states that B12 should be measured annually after cystectomy with bowel diversion (guideline text, not a graded recommendation)[27]; AUA/ASCO/SUO Statement 31 advises laboratory assessment every 3–6 months for 2–3 years after treatment for muscle-invasive bladder cancer, then annually.[4] Functional follow-up must continue alongside disease-specific surveillance.[27][4]

Do not routinely screen or treat asymptomatic bacteriuria in a reconstructed urinary tract; use symptoms and established exceptions, including planned mucosa-breaching urological procedures, to guide culture and treatment.[28]

See Vitamin B12 Supplementation, Urinary Acidifiers and Alkalinizers, and Mucus Management.

T-pouch and Other Alternatives​

The T-pouch replaced the intussuscepted afferent nipple with a serosa-lined ileal tunnel. Its first 40-patient report had one perioperative death unrelated to diversion and no late complications at mean 10.5 months.[29]

The subsequent USC-STAR randomized comparison did not establish superior three-year renal preservation with T-pouch over Studer reconstruction and found more pouch-related reintervention. See T-Pouch Modification for the trial and limitations.[30]

The T-pouch valve was later adapted for continent ileostomy. Kaiser's first report described six patients with complete continence, and his 10-year analysis of 40 patients (median follow-up 6.2 years) reported questionnaire-based good continence in 92%, pouch-related major abdominal surgery in 30% and willingness to repeat the operation in 87.5%.[34][35] The urinary reconstruction choice should balance bowel availability, kidney function, outlet requirements, patient preference and the team's experience.

See Also​

References​

1. Skinner DG, Boyd SD, Lieskovsky G. "Clinical Experience With the Kock Continent Ileal Reservoir for Urinary Diversion." J Urol. 1984;132(6):1101–7. doi:10.1016/s0022-5347(17)50052-x

2. Elmajian DA, Stein JP, Esrig D, et al. "The Kock Ileal Neobladder: Updated Experience in 295 Male Patients." J Urol. 1996;156(3):920–5. doi:10.1016/s0022-5347(01)65663-5

3. Ghoneim MA, Kock NG, Lycke G, el-Din AB. "An Appliance-Free, Sphincter-Controlled Bladder Substitute: The Urethral Kock Pouch." J Urol. 1987;138(5):1150–4. doi:10.1016/s0022-5347(17)43531-2

4. American Urological Association / American Society of Clinical Oncology / Society of Urologic Oncology. Treatment of Non-Metastatic Muscle-Invasive Bladder Cancer: AUA/ASCO/SUO Guideline (2017; Amended 2020, 2024). Statements 13–14 and 31–32 and discussions. Guideline.

5. Skinner DG, Lieskovsky G, Boyd SD. "Continent Urinary Diversion. A 5 1/2 Year Experience." Ann Surg. 1988;208(3):337–44. doi:10.1097/00000658-198809000-00011

6. Arai Y, Okada Y, Matsuda T, et al. "Afferent Nipple Valve Malfunction Caused by Anchoring Collar: An Unexpected Late Complication of the Kock Continent Ileal Reservoir." J Urol. 1991;145(1):29–32. doi:10.1016/s0022-5347(17)38238-1

7. Skinner DG, Lieskovsky G, Boyd SD. "Continuing Experience With the Continent Ileal Reservoir (Kock Pouch) as an Alternative to Cutaneous Urinary Diversion: An Update After 250 Cases." J Urol. 1987;137(6):1140–5. doi:10.1016/s0022-5347(17)44429-6

8. Chen KK, Chang LS, Chen MT, et al. "Clinical Experience of Kock Pouch Continent Urinary Diversion." Urology. 1990;35(4):317–20. doi:10.1016/0090-4295(90)80154-f

9. Henriet MP, Neyra P, Elman B. "Kock Pouch Procedures: Continuing Experience and Evolution in 135 Cases." J Urol. 1991;146(1):16–20. doi:10.1016/s0022-5347(17)37703-0

10. Arai Y, Kawakita M, Terachi T, et al. "Long-Term Followup of the Kock and Indiana Pouch Procedures." J Urol. 1993;150(1):51–5. doi:10.1016/s0022-5347(17)35394-6

11. Okada Y, Shichiri Y, Terai A, et al. "Management of Late Complications of Continent Urinary Diversion Using the Kock Pouch and the Indiana Pouch Procedures." Int J Urol. 1996;3(5):334–9. doi:10.1111/j.1442-2042.1996.tb00549.x

12. Kock NG, Ghoneim MA, Lycke KG, Mahran MR. "Replacement of the Bladder by the Urethral Kock Pouch: Functional Results, Urodynamics and Radiological Features." J Urol. 1989;141(5):1111–6. doi:10.1016/s0022-5347(17)41185-2

13. Ghoneim MA, Shaaban AA, Mahran MR, Kock NG. "Further Experience With the Urethral Kock Pouch." J Urol. 1992;147(2):361–5. doi:10.1016/s0022-5347(17)37238-5

14. Steven K, Poulsen AL. The orthotopic Kock ileal neobladder: functional results, urodynamic features, complications and survival in 166 men. J Urol. 2000;164(2):288–295. doi:10.1016/s0022-5347(05)67343-0. PMID:10893568.

15. Chen KK, Chang LS, Chen MT. "Urodynamic and Clinical Outcome of Kock Pouch Continent Urinary Diversion." J Urol. 1989;141(1):94–7. doi:10.1016/s0022-5347(17)40602-1

16. Gotoh M, Yoshikawa Y, Sahashi M, et al. Urodynamic study of storage and evacuation of urine in patients with a urethral Kock pouch. J Urol. 1995;154(5):1850–1853. doi:10.1016/s0022-5347(01)66798-3. PMID:7563361.

17. Stein JP, Freeman JA, Esrig D, et al. Complications of the afferent antireflux valve mechanism in the Kock ileal reservoir. J Urol. 1996;155(5):1579–1584. doi:10.1016/s0022-5347(01)66131-7. PMID:8627827.

18. Stein JP, Huffman JL, Freeman JA, et al. "Stenosis of the Afferent Antireflux Valve in the Kock Pouch Continent Urinary Diversion: Diagnosis and Management." J Urol. 1994;151(2):338–40. doi:10.1016/s0022-5347(17)34942-x

19. Locke JA, Neu S, Herschorn S. "Diagnosis and Management of Kock Afferent Nipple Valve Obstruction." Urology. 2021;152:173–7. doi:10.1016/j.urology.2021.02.023

20. Carr LK, Webster GD. "Kock Versus Right Colon Continent Urinary Diversion: Comparison of Outcome and Reoperation Rate." Urology. 1996;48(5):711–4. doi:10.1016/S0090-4295(96)00424-4

21. Ginsberg D, Huffman JL, Lieskovsky G, Boyd S, Skinner DG. "Urinary Tract Stones: A Complication of the Kock Pouch Continent Urinary Diversion." J Urol. 1991;145(5):956–9. doi:10.1016/s0022-5347(17)38499-9

22. Terai A, Ueda T, Kakehi Y, et al. Urinary calculi as a late complication of the Indiana continent urinary diversion: comparison with the Kock pouch procedure. J Urol. 1996;155(1):66–68. doi:10.1016/s0022-5347(01)66541-8. PMID:7490900.

23. European Association of Urology. EAU Guidelines on Urolithiasis. 2026. Bladder stones in urinary diversion, sections 6.4.5 and 6.6. Guideline.

24. Pannek J, Haupt G, Schulze H, Senge T. Influence of continent ileal urinary diversion on vitamin B12 absorption. J Urol. 1996;155(4):1206–1208. doi:10.1016/s0022-5347(01)66217-7. PMID:8632531.

25. Terai A, Okada Y, Shichiri Y, et al. "Vitamin B12 Deficiency in Patients With Urinary Intestinal Diversion." Int J Urol. 1997;4(1):21–5. doi:10.1111/j.1442-2042.1997.tb00133.x

26. Abd-el-Gawa G, Abrahamsson K, Norlén L, Hjälmås K, Hanson E. "Vitamin B12 and Folate After 5–12 Years of Continent Ileal Urostomy (Kock Reservoir) in Children and Adolescents." Eur Urol. 2002;41(2):199–205. doi:10.1016/s0302-2838(01)00032-x

27. European Association of Urology. EAU Guidelines on Muscle-invasive and Metastatic Bladder Cancer. 2026. Functional follow-up, section 7.4. Guideline.

28. European Association of Urology. EAU Guidelines on Urological Infections. 2026. Reconstructed lower urinary tracts and asymptomatic bacteriuria, sections 3.3.5.d.5 and 3.3.7. Guideline.

29. Stein JP, Lieskovsky G, Ginsberg DA, Bochner BH, Skinner DG. "The T Pouch: An Orthotopic Ileal Neobladder Incorporating a Serosal Lined Ileal Antireflux Technique." J Urol. 1998;159(6):1836–42. doi:10.1016/S0022-5347(01)63170-7

30. Skinner EC, Fairey AS, Groshen S, et al. Randomized trial of Studer pouch versus T-pouch orthotopic ileal neobladder in patients with bladder cancer. J Urol. 2015;194(2):433–439. doi:10.1016/j.juro.2015.03.101.

31. Angistriotis A, Shen B, Kiran RP. "Construction of and Conversion to Continent Ileostomy: A Systematic Review." Dis Colon Rectum. 2022;65(S1):S26–S36. doi:10.1097/DCR.0000000000002631

32. Nessar G, Wu JS. "Evolution of Continent Ileostomy." World J Gastroenterol. 2012;18(27):3479–82. doi:10.3748/wjg.v18.i27.3479

33. Gerber A. "The Kock Continent Ileal Reservoir for Supravesical Urinary Diversion. An Early Experience." Am J Surg. 1983;146(1):15–20. doi:10.1016/0002-9610(83)90252-0

34. Kaiser AM, Stein JP, Beart RW. "T-Pouch: A New Valve Design for a Continent Ileostomy." Dis Colon Rectum. 2002;45(3):411–5. doi:10.1007/s10350-004-6192-2

35. Kaiser AM. "T-Pouch: Results of the First 10 Years With a Nonintussuscepting Continent Ileostomy." Dis Colon Rectum. 2012;55(2):155–62. doi:10.1097/DCR.0b013e31823a969b

36. Stein JP, Grossfeld GD, Freeman JA, Esrig D, Ginsberg DA, Cote RJ, et al. "Orthotopic Lower Urinary Tract Reconstruction in Women Using the Kock Ileal Neobladder: Updated Experience in 34 Patients." J Urol. 1997;158(2):400-405. doi:10.1016/s0022-5347(01)64488-4

37. European Association of Urology. "EAU Guidelines on Muscle-invasive and Metastatic Bladder Cancer." 2026. Section 6.7.5.b, Patient selection. Guideline.

38. Girgin C, Sezer A, Ozer K, Tarhan H, Bolukbasi A, Gurel G. "Comparison of Three Types of Continent Urinary Diversions in a Single Center." ScientificWorldJournal. 2004;4(Suppl 1):135–141. doi:10.1100/tsw.2004.59