AFFERENT ANTIREFLUX VALVE MECHANISM IN KOCK ILEAL RESERVOIR 1583 W.: Renal scarring and bacteriuria 9-16 years after urinary diversion with and without antirefluxing anastornosis. J. Urol., part 2, 163 302A. abstract 296, 1995.

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EDITORIAL COMMENT

The authors are to be commended for their meticulous report on complications with the afferent antireflux valve mechanism in the Kock ileal reservoir in 802 consecutive patients afler a median ob- servation of 6.1 years. Of the patients 42 (5.2%) had stones in the nipple area associated with the metallic staples exposed to urine, and removed endoscopically in the majority of patients under outpa- tient conditions; 42 (5.2%) had nipple stenosis or prolapse, the ma- jority of cases resulting in upper tract dilatation and requiring en- doscopic or open surgical treatment, and 18 (2.2%) had strictures of the ureteroileal anastomosis requiring open surgical revision in all but 2.

It is interesting to note that antireflux nipple stenosis was diag- nosed in these patients only after an average of 4.6 years and as late as 10 years postoperatively, which stresses again the need for me- ticulous, continuous followup of all patients if permanent damage to the upper urinary tract is to be prevented (63% of the patients were asymptomatic when bilateral hydronephrosis due to nipple stenosis was diagnosed). The rather late occurrence of nipple stenosis seems to be in contrast to the strictures from the tunneled ureterointesthd antireflux techniques, which occur predominantly within 1 or 2 years postoperatively.

m e n comparing the complication rates with the afferent nipple Vdve and other u&.eral antireflux techniques, it is probably correct to combine the 5.2% rate of nipple stenosis or prolapse with the 2.2% ureteroileal stricture rate observed by the authors. Thus, the total of

hors consider an advantage of the nipple valve to be the fact that tpproximately two-thirds of the patients with nipple stenosis could e treated endoscopically but this also seems to be possible for itenotic tunneled ureteral antireflux valves implanted directly into be intestinal reservoir.

Patients reported in various series with different ureteral implan- ation and antireflux techniques are not necessarily comparable. h e n if the overall complication rates from nipple stenoses and mteroileal strictures were within the range of complications noted with the tunneled techniques, it must be stressed that the followup n this series of patients with afferent nipple valves is longer than ;hat usually reported for patients undergoing tunneled implanta- ion. Nevertheless, a particular difference between the intussuscep ted nipple valve and the tunneled antireflux techniques remains. If the nipple valve fails both upper urinary tracts are obstructed, whereas a strictured ureterointestinal implant will only be harmful to 1 kidney.

Persistent outflow obstruction of the upper urinary tract inevita- bly causes renal damage. Therefore, the potential complications and risks of antireflux prevention must be weighed against the potential benefit. In this regard, the authors correctly discriminate between continent reservoirs with competent outlet valves and usually chron- ically infected urine and orthotopic ileal bladder substitutes, which have predominantly sterile urine and in which the membranous urethra acts as a safety valve preventing major pressure spikes. References 11 to 15 in the article, showing that vesicoureteral reflux is harmful to the kidneys, are not necessarily applicable to patients with a low pressure reservoir. The patients studied had normal contracting or neuropathic bladders with coordinated contractions during voiding, resulting in an isolated intravesical pressure in- crease and consequent reflux. Unlike normal bladders, low pressure reservoirs have no major coordinated contractions during voiding. When voiding with the Valsalva maneuver, reflux cannot be pro- voked as the pressures in the reservoir, retroperitoneum and renal pelvis increase simultaneously. Minor pressure spikes in the reser- voir can be dealt with by the unidirectional peristalsis of the ureters and an ileal afferent tubular segment, that is with a dynamic anti- reflux system.

The ileal afferent tubular segment cannot be compared to cutane- ous ileal conduits, which are chronically infected and may cause obstruction, particularly when crossing the abdominal wall. Also, the poor long-term results with ileal ureters to which the authors refer were observed in patients with a high pressure neuropathic bladder. Therefore, these results are not necessarily applicable to patients with an orthotopic low pressure ileal bladder substitute.

Similar to the authors, we also observed a 2% ureteroileal stricture rate but we have noted no obstructions of the afferent tubular ileal segment during the last 10 years. In addition to the low complication rate and ease of surgery, the afferent tubular ileal segment also allows for extensive removal of the distal ureters, which are most prone to neoplastic changes or distal ureteral ischemia and consec- utive scarring. Nevertheless, we fully agree that the late outcome of patients with an ileal bladder substitute combined with an afferent ileal tubular segment is not known. Only careful followup, as dem- onstrated by the authors, of large patient series may allow for more deiinite conclusions.

Regardless of more mature results in different patient series, it must be stressed that the complication rates reported, and usually cited, are for the largest surgical series worldwide and for patients who have undergone surgery by the most experienced physicians. The rates may be higher in less experienced hands. Under these circumstances, the overall 12% complication rate with the afferent antireflux nipple valve and the ureterointestinal anastomosis as reported remains impressive.

Urs E. Studer Department of Urology University of Berne Berne, Switzerland

REPLY BY AUTHORS

7.4% can be compared to the 7 to 8% rate of complications reportel mth the tunneled implantation and antireflux procedures. The au I

We appreciate the thoughtful and critical review of our article. However, several comments deserve mention. We believe that the 4.3% rate of afferent nipple stenosis will decrease as a result of our recent modification in the construction of the afferent limb. Previ- ously, 8 cm. of mesentery were stripped from the mesentery adjacent to the ileal sement to be intussuscepted. Now, only 6 cm. of mesen-

1584 AFFERENT ANTIREFLUX VALVE MECHANISM IN KOCK ILEAL RESERVOIR

tery are stripped. This technique maintains the intussuscepted nip- ple valve mechanism and may also abrogate the ischemic changes in the limb, which we suspect contribute to stenosis of the nipple valve. In addition, stenosis of the afferent nipple is usually short and at the ostium, allowing most cases to be treated successfully with end+ scopic techniques (reference 8 in article). However, most stenoses resulting from tunneled ureterointestinal techniques are longer and may not be treated as easily endoscopically with similar success. Also, recent advances in endoscopic techniques and equipment, with

increasing surgical experience, may render most strictures (afferent nipple and tunneled techniques) amenable to endoscopic therapy. Furthermore, although the failure of the intussuscepted nipple valve places both upper urinary tracts a t risk for renal deterioration, to OW knowledge no patient with a continent Kock ileal reservoir has ever had irreversible renal insufficiency due to nipple failure. However, this fact underscores the need to monitor and follow closely all patients who have undergone lower urinary tract reconstruction incorporating the afferent intussuscepted nipple valve.