- Email: [email protected]
A Prospective, Randomized Trial Evaluating the Use of Hydrogel Coated Latex Versus All Silicone Urethral Catheters After Urethral Reconstructive Surgery
Trauma/Reconstruction/Diversion A Prospective, Randomized Trial Evaluating the Use of Hydrogel Coated Latex Versus All Silicone Urethral Catheters After Urethral Reconstructive Surgery Bradley A. Erickson, Neema Navai, Mukul Patil, Allen Chang and Chris M. Gonzalez* From the Northwestern University Feinberg School of Medicine, Department of Urology, Chicago, Illinois
Purpose: The superiority of silicone over latex based catheters following urethral reconstructive surgery for stricture disease has been theorized, and yet data comparing their use in this group of patients are lacking. We present our findings from a prospective, randomized trial comparing silicone to hydrogel coated latex catheters in patients following urethral reconstructive surgery. Materials and Methods: From February 2004 to August 2006 men undergoing urethral reconstructive surgeries were randomized to receive an all-silicone or a hydrogel coated latex urethral catheter for postoperative bladder drainage. Patient demographics and the various reconstructive procedures used were analyzed. Complications and stricture recurrence were evaluated in the 2 groups. Results: A total of 85 men were randomized to receive a silicone (43) or a latex (42) catheter following reconstructive surgery. Median followup was 20 months (range 10 to 36). Mean patient age, urethral stricture length, complication rate and type of reconstructive procedure did not significantly differ between the 2 groups. Five patients (11%) per group required repeat instrumentation for stricture recurrence (p ⫽ 0.97). Median time to stricture recurrence was not statistically different between the 2 groups. Conclusions: The theoretical benefit of silicone catheters over hydrogel coated latex catheters does not appear to translate into a clinical advantage after urethral reconstructive surgery since we found no difference in the rate of recurrence or operative complications at intermediate term followup. It appears that the 2 types of catheter are appropriate for urethral stenting following urethral reconstructive surgery. Key Words: urethra, catheterization, hydrogel, silicones, urethral stricture
he use of a urethral catheter after reconstructive surgery for urethral stricture disease is almost universal. The catheter serves 3 purposes, that is to provide a template for the urethra to heal in the appropriate circumferential fashion, hasten the approximation of grafts to the underlying vascular bed and drain the bladder of urine, preventing turbulent, high pressure, intraurethral urine that could potentially disrupt new suture lines and cause urinoma.1 Urethral catheters have undergone significant material and design improvements in the last decade.2 The newer generations of urethral catheters generate lower contact friction and cause less urethral and periurethral inflammation than traditional all-latex catheters.3,4 It is hypothesized that these new catheters, including all-silicone and latex based models, may lead to fewer problems with stricture recurrence, although to our knowledge this theory has yet to be tested in a clinical study. Because of historical concerns with all-latex catheters,5–7 many reconstructive urologists are reluctant to use the newer, coated latex catheters and
they continue to advocate the exclusive use of silicone catheters after urethral reconstruction.1,8 However, the new generation of coated latex urethral catheters may offer potential advantages over silicone catheters. These new catheters appear to have inertness similar to that of silicone2 but they are less expensive and generally preferred by patients over traditional catheters.9,10 To evaluate the safety and efficacy of the newer urethral catheters on urethral reconstructive surgery we performed a single institution, prospective, randomized trial of the use of silicone and hydrogel coated latex catheters after urethral reconstructive cases for stricture disease.
T
MATERIALS AND METHODS Randomization/Demographics All men undergoing urethral reconstruction from February 2004 to August 2006, as performed by 1 surgeon (CMG), were included in the study. During this period these patients were randomized to receive a hydrogel coated latex based catheter or an all-silicone catheter after the reconstructive procedure. Randomization was achieved by alternating the use of latex based or all-silicone catheters after each respective case unless there were concerns about latex sensitivity, in which case an all-silicone catheter was used. Perioperative and followup data were kept in a prospectively maintained, institutional review board approved database.
Submitted for publication June 12, 2007. Study received institutional review board approval. * Correspondence: Department of Urology, Northwestern University Feinberg School of Medicine, 303 East Chicago Ave., Tarry 16-703, Chicago, Illinois 60611 (telephone: 312-908-0494; FAX: 312908-7275; e-mail: [email protected]).
0022-5347/08/1791-0203/0 THE JOURNAL OF UROLOGY® Copyright © 2008 by AMERICAN UROLOGICAL ASSOCIATION
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Vol. 179, 203-206, January 2008 Printed in U.S.A. DOI:10.1016/j.juro.2007.08.174
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HYDROGEL COATED OR SILICONE CATHETERS AFTER URETHRAL SURGERY
Catheter Type The 2 types of catheters used during the study were a hydrogel coated, latex based Bardex® Lubricath® Foley catheter and a 100% silicone Kendall-Dover® catheter. An 18Fr catheter was used in 73% of cases in the series with a 16Fr catheter reserved for complicated distal or penile reconstructive cases. The number of patients in each cohort requiring a 16Fr catheter was similar (silicone in 10 and latex in 13).
TABLE 2. Stricture etiology Etiology
No. Silicone
No. Latex
Total No. (%)
Unknown Hypospadias repair failure Instrumentation Erosion Lichen sclerosis Trauma Infection
18 6 9 2 5 2 1
20 9 4 4 1 3 1
38 (45) 15 (17) 13 (15) 6 (7) 6 (7) 5 (6) 2 (2)
43
42
85
Totals
Surgical Procedures All patients were confirmed to have culture negative urine before the procedure. Surgery included EPA, buccal mucosal substitution urethroplasty and 2-stage urethral repair. Buccal grafts in the bulbar urethra were placed dorsal and used only when the length or location of the pathological condition did not make it amenable to EPA. One-stage penile urethroplasty involved ventral placement of a buccal mucosa or skin graft with buccal mucosa being our preferred graft tissue, especially in men with lichen sclerosis or those with failed hypospadias repair. Two-stage repairs involved dorsal placement of buccal mucosa or other graft material surrounding the urethral plate at stage 1 with stage 2 closure 4 to 6 months later. Patients who underwent 2-stage repair were included in analysis only if stage 2 was completed.
Postoperative Management All catheters were removed at postoperative visit 2, generally 2 to 3 weeks after the procedure. Patients were monitored postoperatively by determining post-void residual urine on noninvasive bladder ultrasound and by monitoring urinary symptoms. Routine retrograde urethrogram and cystoscopy were not performed unless there was a return of preoperative symptoms (as demonstrated by a worsening International Prostate Symptom Score), urinary tract infection was noted or the patient had increased post-void residual urine compared to preoperative values. If a recurrent stricture was found, the initial management was DVIU. Repeat urethroplasty was reserved for large segment stricture recurrence or for patients in whom initial DVIU failed.
Statistical Analysis Patient demographics, perioperative complications and stricture recurrence rates were compared between the 2 groups. Chi-square and t test analyses were done when appropriate with p ⱕ0.05 considered significance. Statistical analysis was performed using Microsoft® Office Excel® 11.0 and universally available, web based software (http://www. stat.uiowa.edu/⬃rlenth/Power).
RESULTS A total of 85 men were prospectively randomized to receive a silicone (43) or a latex (42) catheter following reconstructive surgery. Median followup was 20 months (range 10 to 36). Mean patient age, urethral stricture length and the specific type of reconstructive procedure did not significantly differ between the 2 groups (table 1). Stricture etiology was also similar in the 2 groups with most men reporting the cause of the stricture to be unknown (table 2). The complication rate for each type of repair showed no significant differences. There were 6 perioperative complications (14%) in the silicone group and 5 (12%) in the latex group (p ⫽ 0.9, table 3). No patients in the latex group experienced a problem with latex sensitivity and there were no catheter related incidents in either group. Five patients per group required repeat instrumentation for stricture recurrence (p ⫽ 0.97). Stricture length was the only factor appearing to affect stricture recurrence, although statistical significance was not seen (6.7 vs 5.4 cm, p ⫽ 0.32). Subanalysis of repair type revealed modestly higher success rates for EPA vs substitution urethroplasty (94% vs 89%, p ⫽ 0.44), although there was no difference with regard to catheter type (p ⫽ 0.97). Median time to stricture recurrence was not statistically different between the silicone and latex groups (85.1 vs 112.5 days, range 37 to 219, p ⫽ 0.83). Four of the 10 patients confirmed to have recurrence required a single DVIU for short segment ring-shaped recurrences in the bulbar urethra. One patient with a longer segment, ischemicappearing recurrence in the bulbar urethra was also treated with a single DVIU but he currently requires weekly catheterization to remain patent and has refused repeat urethroplasty. Two patients with long segment recurrences in the membranous urethra elected urinary diversion after initial DVIU failed, including a man with a history of radical prostatectomy and adjuvant chemotherapy/pelvic radiation for prostatic rhabdomyosarcoma as a child, and a patient with a history of prostatic urethral injury after pelvic trauma. Three patients required repeat urethroplasty for fossa navicularis stricture failures, of whom 1 presented with a distal urethral fistula. Median followup after secondary procedures was 23 months (range 9.5 to 30).
TABLE 1. Demographics Silicone Mean age (range) No. previous stricture endoscopic dilation/incision (%) Median cm length stricture (range) No. surgical procedure: EPA Substitution urethroplasty 2-Stage repair
43 39
(17–75) (90.1)
5.5 (1–21) 16 18 9
Latex 40 37
(20–75) (88)
4.9 (1.5–22) 16 15 11
TABLE 3. Perioperative complications Complication
No. Silicone (%)
No. Latex (%)
Total No. (%)
Urinary tract infection Hematoma Thromboembolic Fistula
3 (7) 1 (2) 2 (5) 0
1 (2) 2 (5) 1 (2) 1 (2)
4 (5) 3 (4) 3 (4) 1 (1)
6
5
Totals
11
HYDROGEL COATED OR SILICONE CATHETERS AFTER URETHRAL SURGERY DISCUSSION Our prospective, randomized study found no differences in postoperative complications or the recurrence rate of urethral strictures between the 2 cohorts of patients at a median followup of 20 months, indicating that each catheter type can be safely used in patients after urethroplasty. The 2 catheters also appear to be durable for postoperative urethral stenting since none malfunctioned or needed replacement during the study course. These data are similar to those in previous urological studies of catheter use after radical prostatectomy and transurethral prostate resection, in which the rates of postoperative bladder neck contracture and urethral stricture formation were unrelated to the specific type or diameter of urethral catheter used, or the time that the catheter was left in place.11,12 Before the commencement of our study it was our practice to use only silicone catheters after urethral reconstructive surgery for stricture disease. This practice was in place due to historical concerns with latex catheters, which have been implicated in complications ranging from iatrogenic panurethral strictures to systemic toxic shock.5,7,13 Traditional latex catheters, which we considered for study purposes to be latex catheters without a protective coating, generate a large periurethral inflammatory reaction that is capable of dramatically decreasing local urethral blood flow.13 While the likely culprit of these pathological inflammatory reactions was later found to be an impurity in the latex that has since been eliminated,5 concerns about latex catheters have rightfully persisted. A new class of coated latex catheters claiming to be as safe as silicone catheters was developed to prevent these complications with the added benefits of being slightly less expensive and with the potential to be more comfortable for patients.14 Because of these benefits, these catheters were rapidly embraced by the general medical community and they are now used in more than 90% of patients requiring urethral catheterization in a hospital setting.15 Their acceptance in the urological community has not been as prompt, especially as pertains to their use after urethral reconstructive surgery for stricture disease. Accordingly we thought that a study designed to test the safety of these newer latex catheters after urethral reconstruction was warranted. The Kendall-Dover silicone catheter used in the study has many characteristics that make it attractive for use after urethroplasty. Silicone is entirely biocompatible and its use as a urethral catheter generates little urethral epithelial inflammation,2,16 an important attribute when trying to minimize scar formation and suture line contracture after urethroplasty. Silicone is also an inherently strong material compared to latex. This intrinsic strength allows for the silicone catheter to have a thinner wall relative to a circumference matched latex catheter, which effectively increases lumen size for urinary drainage.17 Studies directly comparing silicone catheters to traditional latex catheters showed that silicone models cause less iatrogenic urethral strictures,7 are less prone to kinking and have better flow properties, allowing them to drain the bladder more efficiently than sized matched latex catheters.18 However, despite their larger lumen size and better flow parameters studies indicated that silicone catheters are more susceptible to encrustation, blockage and other catheter related problems, eg balloon malfunction requiring reinsertion, compared to
205
the newer generation of coated latex catheters.2 The increased strength of silicone catheters also tends to make them stiff, causing more patient related discomfort than latex catheters.2 The Bardex Lubricath latex based Foley catheters used in the study were coated with hydrogel, a class of cross-linked macromolecular polymers with unique properties, making them hydrophilic and inert.2,15 In an aqueous environment the hydrogel molecule absorbs a large amount of water, resulting in a thin aqueous film on the outside of the catheter that serves to increase its smoothness and lubricity, and protect the urethra from the underlying latex.2,17 In vivo studies of hydrogel coated catheters showed that they generate only minimal urethral inflammation and have a lower retention force (an indirect measure of surface friction) than silicone catheters, which has been postulated to act as a tool to predict catheter related irritation of the urethral epithelium.14,18 However, as with silicone catheters, there are conceivable problems with hydrogel coated latex catheters. Nonuniform hydrogel coating and cracking of the hydrogel surface after catheter bending have been demonstrated, illustrating that even with the protective coating there remains the potential for the urethral epithelium and new anastomosis to be exposed to raw latex material.17 Despite their structural differences we found no statistical differences in terms of the complication or recurrence rate between the 2 described catheters when used after urethral reconstruction. While previous studies showed that it is probable to find more patients with recurrent stricture disease at a longer time out from surgery,19 we believe that it is unlikely that differences in stricture rates between the 2 cohorts would begin to emerge at longer followup. We also recognize that that the study was underpowered to detect minor differences between the catheters, although it must be noted that achieving a sufficient power in urethral reconstruction studies is extremely difficult. For example, when designing this study, we calculated that to detect a 10% difference in recurrence rates between the 2 catheters would require almost 200 study participants per cohort, which is a population that could not be achieved at our institution in a reasonable period. We instead elected to enroll consecutive patients during a 30-month period, knowing that only major differences would be uncovered. Because none existed, we are comfortable in concluding that each catheter is relatively safe for use after urethroplasty, while acknowledging that only larger, multi-institutional studies would be able to decipher the superiority of 1 type of catheter over another in regard to recurrence prevention. We must also recognize that monitoring these men postoperatively with a more stringent protocol, including routine retrograde urethrogram and/or cystoscopy, may have revealed more asymptomatic recurrences, which for the interests of this study might have uncovered nonclinical differences between the groups. Finally, this study would have ideally included a complementary patient preference evaluation. However, despite initial attempts at designing an appropriate questionnaire it proved to be extremely difficult in a population in which many patients had never before experienced long-term catheterization. Instead, we are left to extrapolate findings from other populations that are better suited to determine preference. Studies in the chronic indwelling catheter and intermittent catheterization populations revealed that the increased softness and superior
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HYDROGEL COATED OR SILICONE CATHETERS AFTER URETHRAL SURGERY
lubricity of the coated latex catheters led most patients to prefer this variety over traditional models.9,10 However, whether we could apply these findings to our population is conjecture. Accordingly the findings of this study do not allow us to conclude that 1 type of catheter is superior to the other. Rather, the results simply emphasize that the only essential requirements for urethral catheters after urethral reconstructive surgery are to be biocompatible, inert and to drain the bladder adequately. What is interesting to consider is whether a catheter could be engineered to interact with the urethral epithelium in a beneficial manner. Could the same biotechnology that produced these biologically inert catheters be used to produce a catheter that improves imbibition or even hastens inosculation of a replacement graft by releasing angiogenic growth factors?20 As our understanding of wound healing and urethral stricture disease continues to mature, these uses for urethral catheters may come to fruition. For now it appears that hydrogel coated latex and silicone catheters are equally well suited for urethral stenting after urethroplasty. CONCLUSIONS We compared the use of 2 commonly used catheters after urethral reconstructive surgery. We found no differences in the postoperative complication or recurrent stricture rate at a median followup of 20 months. Based on these findings we believe that the use of an all-silicone catheter or a hydrogel coated latex catheter is appropriate after reconstructive surgery for urethral stricture disease.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
ACKNOWLEDGMENTS Dr. John Cashy assisted with statistical analysis and study design.
14.
15.
Abbreviations and Acronyms DVIU ⫽ direct visual internal urethrotomy EPA ⫽ excision and primary anastomosis REFERENCES 1.
2.
Jordan GH and Schlossberg SM: Surgery of the penis and urethra. In: Campbell’s Urology, 8th ed. Edited by PC Walsh, AB Retik, ED Vaughn Jr and AJ Wein. Philadelphia: WB Saunders Co 2002: p 3886. Lawrence EL and Turner IG: Materials for urinary catheters: a review of their history and development in the UK. Med Eng Phys 2005; 27: 443.
16. 17.
18.
19.
20.
Bull E, Chilton CP, Gould CA and Sutton TM: Single-blind, randomised, parallel group study of the Bard Biocath catheter and a silicone elastomer coated catheter. Br J Urol 1991; 68: 394. Talja M, Korpela A and Jarvi K: Comparison of urethral reaction to full silicone, hydrogel-coated and siliconised latex catheters. Br J Urol 1990; 66: 652. Ferrie BG, Groome J, Sethia B and Kirk D: Comparison of silicone and latex catheters in the development of urethral stricture after cardiac surgery. Br J Urol 1986; 58: 549. Nacey JN, Horsfall DJ, Delahunt B and Marshall VR: The assessment of urinary catheter toxicity using cell cultures: validation by comparison with an animal model. J Urol 1986; 136: 706. Nacey JN, Tulloch AG and Ferguson AF: Catheter-induced urethritis: a comparison between latex and silicone catheters in a prospective clinical trial. Br J Urol 1985; 57: 325. Santucci RA, Mario LA and McAninch JW: Anastomotic urethroplasty for bulbar urethral stricture: analysis of 168 patients. J Urol 2002; 167: 1715. Vapnek JM, Maynard FM and Kim J: A prospective randomized trial of the LoFric hydrophilic coated catheter versus conventional plastic catheter for clean intermittent catheterization. J Urol 2003; 169: 994. Diokno AC, Mitchell BA, Nash AJ and Kimbrough JA: Patient satisfaction and the LoFric catheter for clean intermittent catheterization. J Urol 1995; 153: 349. Borboroglu PG, Sands JP, Roberts JL and Amling CL: Risk factors for vesicourethral anastomotic stricture after radical prostatectomy. Urology 2000; 56: 96. Hart AJ and Fowler JW: Incidence of urethral stricture after transurethral resection of prostate. Effects of urinary infection, urethral flora, and catheter material and size. Urology 1981; 18: 588. Talja M, Virtanen J and Andersson LC: Toxic catheters and diminished urethral blood circulation in the induction of urethral strictures. Eur Urol 1986; 12: 340. Nacey JN and Delahunt B: Toxicity study of first and second generation hydrogel-coated latex urinary catheters. Br J Urol 1991; 67: 314. Bard Medical Division. Clinical Services. Available at www. bardmedical.com. Accessed 2007. Beiko DT, Knudsen BE, Watterson JD and Denstedt JD: Biomaterials in urology. Curr Urol Rep 2003; 4: 51. Lawrence EL and Turner IG: Kink, flow and retention properties of urinary catheters part 1: conventional Foley catheters. J Mater Sci Mater Med 2006; 17: 147. Lawrence EL and Turner IG: Characterisation of the internal and external surfaces of four types of Foley catheter using SEM and profilometry. J Mater Sci Mater Med 2006; 17: 1421. Barbagli G, Palminteri E, Lazzeri M, Guazzoni G and Turini D: Long-term outcome of urethroplasty after failed urethrotomy versus primary repair. J Urol 2001; 165: 1918. Fischbach C and Mooney DJ: Polymers for pro- and antiangiogenic therapy. Biomaterials 2007; 12: 2069.
Purpose: The superiority of silicone over latex based catheters following urethral reconstructive surgery for stricture disease has been theorized, and yet data comparing their use in this group of patients are lacking. We present our findings from a prospective, randomized trial comparing silicone to hydrogel coated latex catheters in patients following urethral reconstructive surgery. Materials and Methods: From February 2004 to August 2006 men undergoing urethral reconstructive surgeries were randomized to receive an all-silicone or a hydrogel coated latex urethral catheter for postoperative bladder drainage. Patient demographics and the various reconstructive procedures used were analyzed. Complications and stricture recurrence were evaluated in the 2 groups. Results: A total of 85 men were randomized to receive a silicone (43) or a latex (42) catheter following reconstructive surgery. Median followup was 20 months (range 10 to 36). Mean patient age, urethral stricture length, complication rate and type of reconstructive procedure did not significantly differ between the 2 groups. Five patients (11%) per group required repeat instrumentation for stricture recurrence (p ⫽ 0.97). Median time to stricture recurrence was not statistically different between the 2 groups. Conclusions: The theoretical benefit of silicone catheters over hydrogel coated latex catheters does not appear to translate into a clinical advantage after urethral reconstructive surgery since we found no difference in the rate of recurrence or operative complications at intermediate term followup. It appears that the 2 types of catheter are appropriate for urethral stenting following urethral reconstructive surgery. Key Words: urethra, catheterization, hydrogel, silicones, urethral stricture
he use of a urethral catheter after reconstructive surgery for urethral stricture disease is almost universal. The catheter serves 3 purposes, that is to provide a template for the urethra to heal in the appropriate circumferential fashion, hasten the approximation of grafts to the underlying vascular bed and drain the bladder of urine, preventing turbulent, high pressure, intraurethral urine that could potentially disrupt new suture lines and cause urinoma.1 Urethral catheters have undergone significant material and design improvements in the last decade.2 The newer generations of urethral catheters generate lower contact friction and cause less urethral and periurethral inflammation than traditional all-latex catheters.3,4 It is hypothesized that these new catheters, including all-silicone and latex based models, may lead to fewer problems with stricture recurrence, although to our knowledge this theory has yet to be tested in a clinical study. Because of historical concerns with all-latex catheters,5–7 many reconstructive urologists are reluctant to use the newer, coated latex catheters and
they continue to advocate the exclusive use of silicone catheters after urethral reconstruction.1,8 However, the new generation of coated latex urethral catheters may offer potential advantages over silicone catheters. These new catheters appear to have inertness similar to that of silicone2 but they are less expensive and generally preferred by patients over traditional catheters.9,10 To evaluate the safety and efficacy of the newer urethral catheters on urethral reconstructive surgery we performed a single institution, prospective, randomized trial of the use of silicone and hydrogel coated latex catheters after urethral reconstructive cases for stricture disease.
T
MATERIALS AND METHODS Randomization/Demographics All men undergoing urethral reconstruction from February 2004 to August 2006, as performed by 1 surgeon (CMG), were included in the study. During this period these patients were randomized to receive a hydrogel coated latex based catheter or an all-silicone catheter after the reconstructive procedure. Randomization was achieved by alternating the use of latex based or all-silicone catheters after each respective case unless there were concerns about latex sensitivity, in which case an all-silicone catheter was used. Perioperative and followup data were kept in a prospectively maintained, institutional review board approved database.
Submitted for publication June 12, 2007. Study received institutional review board approval. * Correspondence: Department of Urology, Northwestern University Feinberg School of Medicine, 303 East Chicago Ave., Tarry 16-703, Chicago, Illinois 60611 (telephone: 312-908-0494; FAX: 312908-7275; e-mail: [email protected]).
0022-5347/08/1791-0203/0 THE JOURNAL OF UROLOGY® Copyright © 2008 by AMERICAN UROLOGICAL ASSOCIATION
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Vol. 179, 203-206, January 2008 Printed in U.S.A. DOI:10.1016/j.juro.2007.08.174
204
HYDROGEL COATED OR SILICONE CATHETERS AFTER URETHRAL SURGERY
Catheter Type The 2 types of catheters used during the study were a hydrogel coated, latex based Bardex® Lubricath® Foley catheter and a 100% silicone Kendall-Dover® catheter. An 18Fr catheter was used in 73% of cases in the series with a 16Fr catheter reserved for complicated distal or penile reconstructive cases. The number of patients in each cohort requiring a 16Fr catheter was similar (silicone in 10 and latex in 13).
TABLE 2. Stricture etiology Etiology
No. Silicone
No. Latex
Total No. (%)
Unknown Hypospadias repair failure Instrumentation Erosion Lichen sclerosis Trauma Infection
18 6 9 2 5 2 1
20 9 4 4 1 3 1
38 (45) 15 (17) 13 (15) 6 (7) 6 (7) 5 (6) 2 (2)
43
42
85
Totals
Surgical Procedures All patients were confirmed to have culture negative urine before the procedure. Surgery included EPA, buccal mucosal substitution urethroplasty and 2-stage urethral repair. Buccal grafts in the bulbar urethra were placed dorsal and used only when the length or location of the pathological condition did not make it amenable to EPA. One-stage penile urethroplasty involved ventral placement of a buccal mucosa or skin graft with buccal mucosa being our preferred graft tissue, especially in men with lichen sclerosis or those with failed hypospadias repair. Two-stage repairs involved dorsal placement of buccal mucosa or other graft material surrounding the urethral plate at stage 1 with stage 2 closure 4 to 6 months later. Patients who underwent 2-stage repair were included in analysis only if stage 2 was completed.
Postoperative Management All catheters were removed at postoperative visit 2, generally 2 to 3 weeks after the procedure. Patients were monitored postoperatively by determining post-void residual urine on noninvasive bladder ultrasound and by monitoring urinary symptoms. Routine retrograde urethrogram and cystoscopy were not performed unless there was a return of preoperative symptoms (as demonstrated by a worsening International Prostate Symptom Score), urinary tract infection was noted or the patient had increased post-void residual urine compared to preoperative values. If a recurrent stricture was found, the initial management was DVIU. Repeat urethroplasty was reserved for large segment stricture recurrence or for patients in whom initial DVIU failed.
Statistical Analysis Patient demographics, perioperative complications and stricture recurrence rates were compared between the 2 groups. Chi-square and t test analyses were done when appropriate with p ⱕ0.05 considered significance. Statistical analysis was performed using Microsoft® Office Excel® 11.0 and universally available, web based software (http://www. stat.uiowa.edu/⬃rlenth/Power).
RESULTS A total of 85 men were prospectively randomized to receive a silicone (43) or a latex (42) catheter following reconstructive surgery. Median followup was 20 months (range 10 to 36). Mean patient age, urethral stricture length and the specific type of reconstructive procedure did not significantly differ between the 2 groups (table 1). Stricture etiology was also similar in the 2 groups with most men reporting the cause of the stricture to be unknown (table 2). The complication rate for each type of repair showed no significant differences. There were 6 perioperative complications (14%) in the silicone group and 5 (12%) in the latex group (p ⫽ 0.9, table 3). No patients in the latex group experienced a problem with latex sensitivity and there were no catheter related incidents in either group. Five patients per group required repeat instrumentation for stricture recurrence (p ⫽ 0.97). Stricture length was the only factor appearing to affect stricture recurrence, although statistical significance was not seen (6.7 vs 5.4 cm, p ⫽ 0.32). Subanalysis of repair type revealed modestly higher success rates for EPA vs substitution urethroplasty (94% vs 89%, p ⫽ 0.44), although there was no difference with regard to catheter type (p ⫽ 0.97). Median time to stricture recurrence was not statistically different between the silicone and latex groups (85.1 vs 112.5 days, range 37 to 219, p ⫽ 0.83). Four of the 10 patients confirmed to have recurrence required a single DVIU for short segment ring-shaped recurrences in the bulbar urethra. One patient with a longer segment, ischemicappearing recurrence in the bulbar urethra was also treated with a single DVIU but he currently requires weekly catheterization to remain patent and has refused repeat urethroplasty. Two patients with long segment recurrences in the membranous urethra elected urinary diversion after initial DVIU failed, including a man with a history of radical prostatectomy and adjuvant chemotherapy/pelvic radiation for prostatic rhabdomyosarcoma as a child, and a patient with a history of prostatic urethral injury after pelvic trauma. Three patients required repeat urethroplasty for fossa navicularis stricture failures, of whom 1 presented with a distal urethral fistula. Median followup after secondary procedures was 23 months (range 9.5 to 30).
TABLE 1. Demographics Silicone Mean age (range) No. previous stricture endoscopic dilation/incision (%) Median cm length stricture (range) No. surgical procedure: EPA Substitution urethroplasty 2-Stage repair
43 39
(17–75) (90.1)
5.5 (1–21) 16 18 9
Latex 40 37
(20–75) (88)
4.9 (1.5–22) 16 15 11
TABLE 3. Perioperative complications Complication
No. Silicone (%)
No. Latex (%)
Total No. (%)
Urinary tract infection Hematoma Thromboembolic Fistula
3 (7) 1 (2) 2 (5) 0
1 (2) 2 (5) 1 (2) 1 (2)
4 (5) 3 (4) 3 (4) 1 (1)
6
5
Totals
11
HYDROGEL COATED OR SILICONE CATHETERS AFTER URETHRAL SURGERY DISCUSSION Our prospective, randomized study found no differences in postoperative complications or the recurrence rate of urethral strictures between the 2 cohorts of patients at a median followup of 20 months, indicating that each catheter type can be safely used in patients after urethroplasty. The 2 catheters also appear to be durable for postoperative urethral stenting since none malfunctioned or needed replacement during the study course. These data are similar to those in previous urological studies of catheter use after radical prostatectomy and transurethral prostate resection, in which the rates of postoperative bladder neck contracture and urethral stricture formation were unrelated to the specific type or diameter of urethral catheter used, or the time that the catheter was left in place.11,12 Before the commencement of our study it was our practice to use only silicone catheters after urethral reconstructive surgery for stricture disease. This practice was in place due to historical concerns with latex catheters, which have been implicated in complications ranging from iatrogenic panurethral strictures to systemic toxic shock.5,7,13 Traditional latex catheters, which we considered for study purposes to be latex catheters without a protective coating, generate a large periurethral inflammatory reaction that is capable of dramatically decreasing local urethral blood flow.13 While the likely culprit of these pathological inflammatory reactions was later found to be an impurity in the latex that has since been eliminated,5 concerns about latex catheters have rightfully persisted. A new class of coated latex catheters claiming to be as safe as silicone catheters was developed to prevent these complications with the added benefits of being slightly less expensive and with the potential to be more comfortable for patients.14 Because of these benefits, these catheters were rapidly embraced by the general medical community and they are now used in more than 90% of patients requiring urethral catheterization in a hospital setting.15 Their acceptance in the urological community has not been as prompt, especially as pertains to their use after urethral reconstructive surgery for stricture disease. Accordingly we thought that a study designed to test the safety of these newer latex catheters after urethral reconstruction was warranted. The Kendall-Dover silicone catheter used in the study has many characteristics that make it attractive for use after urethroplasty. Silicone is entirely biocompatible and its use as a urethral catheter generates little urethral epithelial inflammation,2,16 an important attribute when trying to minimize scar formation and suture line contracture after urethroplasty. Silicone is also an inherently strong material compared to latex. This intrinsic strength allows for the silicone catheter to have a thinner wall relative to a circumference matched latex catheter, which effectively increases lumen size for urinary drainage.17 Studies directly comparing silicone catheters to traditional latex catheters showed that silicone models cause less iatrogenic urethral strictures,7 are less prone to kinking and have better flow properties, allowing them to drain the bladder more efficiently than sized matched latex catheters.18 However, despite their larger lumen size and better flow parameters studies indicated that silicone catheters are more susceptible to encrustation, blockage and other catheter related problems, eg balloon malfunction requiring reinsertion, compared to
205
the newer generation of coated latex catheters.2 The increased strength of silicone catheters also tends to make them stiff, causing more patient related discomfort than latex catheters.2 The Bardex Lubricath latex based Foley catheters used in the study were coated with hydrogel, a class of cross-linked macromolecular polymers with unique properties, making them hydrophilic and inert.2,15 In an aqueous environment the hydrogel molecule absorbs a large amount of water, resulting in a thin aqueous film on the outside of the catheter that serves to increase its smoothness and lubricity, and protect the urethra from the underlying latex.2,17 In vivo studies of hydrogel coated catheters showed that they generate only minimal urethral inflammation and have a lower retention force (an indirect measure of surface friction) than silicone catheters, which has been postulated to act as a tool to predict catheter related irritation of the urethral epithelium.14,18 However, as with silicone catheters, there are conceivable problems with hydrogel coated latex catheters. Nonuniform hydrogel coating and cracking of the hydrogel surface after catheter bending have been demonstrated, illustrating that even with the protective coating there remains the potential for the urethral epithelium and new anastomosis to be exposed to raw latex material.17 Despite their structural differences we found no statistical differences in terms of the complication or recurrence rate between the 2 described catheters when used after urethral reconstruction. While previous studies showed that it is probable to find more patients with recurrent stricture disease at a longer time out from surgery,19 we believe that it is unlikely that differences in stricture rates between the 2 cohorts would begin to emerge at longer followup. We also recognize that that the study was underpowered to detect minor differences between the catheters, although it must be noted that achieving a sufficient power in urethral reconstruction studies is extremely difficult. For example, when designing this study, we calculated that to detect a 10% difference in recurrence rates between the 2 catheters would require almost 200 study participants per cohort, which is a population that could not be achieved at our institution in a reasonable period. We instead elected to enroll consecutive patients during a 30-month period, knowing that only major differences would be uncovered. Because none existed, we are comfortable in concluding that each catheter is relatively safe for use after urethroplasty, while acknowledging that only larger, multi-institutional studies would be able to decipher the superiority of 1 type of catheter over another in regard to recurrence prevention. We must also recognize that monitoring these men postoperatively with a more stringent protocol, including routine retrograde urethrogram and/or cystoscopy, may have revealed more asymptomatic recurrences, which for the interests of this study might have uncovered nonclinical differences between the groups. Finally, this study would have ideally included a complementary patient preference evaluation. However, despite initial attempts at designing an appropriate questionnaire it proved to be extremely difficult in a population in which many patients had never before experienced long-term catheterization. Instead, we are left to extrapolate findings from other populations that are better suited to determine preference. Studies in the chronic indwelling catheter and intermittent catheterization populations revealed that the increased softness and superior
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lubricity of the coated latex catheters led most patients to prefer this variety over traditional models.9,10 However, whether we could apply these findings to our population is conjecture. Accordingly the findings of this study do not allow us to conclude that 1 type of catheter is superior to the other. Rather, the results simply emphasize that the only essential requirements for urethral catheters after urethral reconstructive surgery are to be biocompatible, inert and to drain the bladder adequately. What is interesting to consider is whether a catheter could be engineered to interact with the urethral epithelium in a beneficial manner. Could the same biotechnology that produced these biologically inert catheters be used to produce a catheter that improves imbibition or even hastens inosculation of a replacement graft by releasing angiogenic growth factors?20 As our understanding of wound healing and urethral stricture disease continues to mature, these uses for urethral catheters may come to fruition. For now it appears that hydrogel coated latex and silicone catheters are equally well suited for urethral stenting after urethroplasty. CONCLUSIONS We compared the use of 2 commonly used catheters after urethral reconstructive surgery. We found no differences in the postoperative complication or recurrent stricture rate at a median followup of 20 months. Based on these findings we believe that the use of an all-silicone catheter or a hydrogel coated latex catheter is appropriate after reconstructive surgery for urethral stricture disease.
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ACKNOWLEDGMENTS Dr. John Cashy assisted with statistical analysis and study design.
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Abbreviations and Acronyms DVIU ⫽ direct visual internal urethrotomy EPA ⫽ excision and primary anastomosis REFERENCES 1.
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