In 1980, Mitrofanoff described a continence mechanism using the appendix or ureter to create a flap valve, and at the same time a catheterizable conduit to the bladder from the abdominal wall. (1,2)  As an alternative, the hemi-Kock system, which is constructed from approximately 40 cm. of terminal ileum, and comprises a detubularized and remodeled ileal plate with a stapled ileoileal intussusception to form a 1-way valve was first described in 1993.(3)  While there have been multiple reports of the former procedure there are very few publications of the latter system. Since it potentially addresses the complex problems that may be encountered in men and women with neurogenic lower urinary tract dysfunction, we have employed it as an option in patients who require but cannot perform urethral intermittent catheterization (CIC), have bladder storage abnormalities, and who may have incompetent outlets that can be treated simultaneously. 

A cohort of patients who underwent a hemi-Kock continent cutaneous bladder stoma, along with other procedures as required, was analyzed to assess outcomes including long-term durability and the need for revisional surgery.

This is a retrospective report of a prospectively followed case series from a single institution. 

The patients were selected as candidates after clinical examination, upper tract imaging, renal function testing, videourodynamic studies, cystoscopy, and skills assessment. A total of 92 patients, 69 women and 23 men with a mean age of 36.8 years (range 18-69) underwent the procedure, primarily for intractable urinary incontinence. Diagnoses were spinal cord injury (45), spina bifida (23), MS (6), transverse myelitis (2), other neurologic causes (16). Preoperative management consisted of Foley catheter in 58 patients, suprapubic catheter in 12, and condom or diapers with or without CIC in 22. 

During the surgery, in addition to the intussuscepted ileal segment continent bladder stoma, 87 patients had a cystoplasty with adjacent ileum and 5 had sigmoid cystoplasty. To address urethral incompetence in the women, 58 had the following procedures: bladder neck (BN) slings in 34, slings with BN tapering in 14, and BN closure in 10. In the 12 men with urethral incompetence, 9 had BN slings with tapering while 3 had BN closure. The patients were followed regularly over time. Stomal and valve revision rates, all surgical re-interventions, and overall success were analyzed on the basis of ongoing data collection. Success was defined as persistence with CIC and social continence.

The mean follow-up after surgery was 8.8 years (median 7.2; range .33-27.2). All of the patients, except 2 quadriplegic women, carried out their own stomal CIC. Bladder capacity increased significantly (203 cc to 433 cc) while pressure at capacity decreased from 37 cm water to 9 cm water (both - P<0.0001). 

At last follow-up, 80 patients (87.5%) were managing with CIC  ±pads and considered themselves to have had successful reconstructions. Eleven (12.5%) were failures and of these, 7 have indwelling catheters and 4 had ileal conduits. 

A total of 36 patients (39%) have not required any additional surgery. The table shows the secondary procedures that have been done in 56 (61%) patients. Of the 12 patients who required valve revisions 10 were done early in the series. A modification to prevent valve extrusion which involved tapering the efferent limb was added and this largely prevented this complication. Of the total of 71 re-interventions 45 (63%) were under local anaesthetic or endocopically and 26 (37%) were with open surgery. 56 patients had 1 or more revisions, 23 had 2 or more, with substantially decreasing numbers thereafter. The mean time from the original procedure to the first revision was 5 years; to the second was 9.7 years; and to the third was 10.9 years.

3 patients have died from unrelated causes and 1 died from metatstatic urothelial cancer 15 years after augmentation. 2 women had full term pregnancies. No other significant morbidity has been seen.

In this study, which is the largest reported to date, the hemi-Kock augmentation cystoplasty with continent abdominal stoma appears to be a good option for patients with neurogenic lower urinary tract disorders who are unable to do urethral catheterization and who require a cystoplasty. The benefit of doing a urethral incontinence procedure if required, is to maintain urethral access should the efferent limb become difficult or impossible to catheterize. A benefit of the hemi-Kock system over an appendiceal Mitrofanoff is the larger caliber limb allows for catheterization with a larger size catheter to permit irrigaton and flushing out of mucus, and the use of a rigid cystoscope for litholapaxy, if necessary.

Long -term durability and successful management may often be seen with this procedure. However, It is apparent from the data that ongoing follow-up is needed to identify problems and long-term follow-up is required since re-interventions may be not needed until long after the original surgery.

Mitrofanoff P. [Trans-appendicular continent cystostomy in the management of the neurogenic bladder]. Chir Pediatr. 1980;21(4):297-305.
Keating MA, Rink RC, Adams MC. Appendicovesicostomy: a useful adjunct to continent reconstruction of the bladder. J Urol. May 1993;149(5):1091-1094.
Kreder K, Das AK, Webster GD. The hemi-Kock ileocystoplasty: a versatile procedure in reconstructive urology. J Urol. May 1992;147(5):1248-1251.