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Outcome Analysis of the Modified Mathieu Hypospadias Repair: Comparison of Stented and Unstented Repairs
0022-5347/96/1562-0836$03.00/0
THE JOURNAL
Vol. 156,836-838,August 1996 Printed in U.SA.
OF UROLoCY
Copyright 0 1996 by AMERICAS UROLOCICAL ASSOCIATION, IKC.
OUTCOME ANALYSIS OF THE MODIFIED MATHIEU HYPOSPADIAS REPAIR: COMPARISON OF STENTED AND UNSTENTED REPAIRS SAMUEL HAKIM, PAUL A. MERGUERIAN,* RONALD W I N O W I T Z , LINDA D. SHORTLIFFE PATRICK H. McKENNA
AND
From the Department of Surgery, Section of Urology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, Department of Urology. Division of Pediatric Urology, Stanford University Medical Center, Stanford, California, and Departments of Urology, University of Rochester Medical Center, Rochester, New York, and Naval Regional Medical Center, Portsmouth, Virginia
ABSTRACT
Purpose: We compared surgical outcomes of stented and unstented Mathieu repairs in boys with primary distal hypospadias, and evaluated the efficacy and safety of caudal analgesia relative to other forms of analgesia (penile block and epidural analgesia). Materials and Methods: We retrospectively reviewed the records of 336 consecutive boys who underwent the modified Mathieu repair for primary distal hypospadias. A urethral stent was placed in 114 patients and nonstented repair was performed in 222. Adjunct caudal analgesia was given in 136 cases, a penile block in 158 and continuous epidural analgesia in 42. Results: None of the unstented cases had urinary retention. Analysis of surgical outcomes revealed no difference in fistula formation between patients with and without stents (2.63 versus 2.70%,respectively, p ~3.999).Overall complication rates in the stented and unstented groups were not significantly different (2.63 versus 3.60%,respectively, p = 0.756). The fistula rate in patients who received adjunct caudal analgesia was no different than in those who received other forms of adjunct analgesia (2.21 versus 3.0%,respectively, p >0.999). Conclusions: These data suggest that successful Mathieu hypospadias repair is independent of the use of a stent. Caudal analgesia, a penile block and epidural analgesia provided effective postoperative pain control with no difference in complication rates. To our knowledge our report represents the largest observational study reported to date comparing stented and unstented repairs. However, because of the small number of complications in each group, a much larger study is required to determine statistically significant differences among these groups. KEY WORDS:penis, hypospadias, stents, complications, analgesia
The Mathieu repair for primary distal hypospadias has been shown to be safe and effective when performed without catheter drainage on an outpatient basis.’-4 In his initial series of meatal based flap repair for distal hypospadias Mathieu did not use catheter drainage.’ In 1987 Rabinowitz reported excellent results in his series of outpatient noncatheter hypospadias repair using a modification of the Mathieu technique.2 Others have reported similar findings.3.4 Significant morbidity has been associated with urethral stents, including infection, bladder spasm and migration. Nevertheless, despite these findings there remains disagreement on the need for urethral catheters or stents in primary hypospadias repair.s5 Recently Buson et a1 reported a n 18.9%complication rate (13.5%fistula rate) in unstented Mathieu repairs compared to a 4.6%complication rate (1.5% fistula rate) when a stent was used.5 They concluded that a urethral stent was advantageous, and believed that the short-term use of a stent should be considered standard for meatal based flaps.5 However, Rabinowitz noted other potential etiologies for the higher fistula rate in the unstented group, including meatal stenosis and postoperative urethral manipulation for urinary retention.5 Also, caudal analgesia is thought to increase the risk of urinary retention and potentially the risk of urethrocutaneous fistula.5 Therefore, we The opinions and assertions contained herein are the private views of the authors and are not to be construed as reflecting the views of the United States Navy, Air Force or De artment of Defense. * Requests for reprints: Department o!Urology, Division of Pediatric Urology, Stanford University Medical Center, Stanford, California 94305.
performed a multi-institutional retrospective study to compare complication rates in the modified Mathieu repair performed with and without a catheter as well as the results of caudal analgesia, and penile and continuous epidural blocks. Outcomes after 1 and 2-layer repairs were also evaluated. SUBJECTS AND METHODS
A total of 336 consecutive boys 5 months to 13 years old (average age 19.9 months) underwent the modified Mathieu repair for primary distal penile hypospadias at 4 institutions. Four groups were analyzed from 4 pediatric urologists. Group 1 (P.A.M.) consisted of 77 boys who underwent Mathieu repair without a urethral stent of whom 73 received adjunct caudal analgesia and 4 received a penile block. Group 2 (R. R.) consisted of 145 boys without a urethral stent who received a penile block. Group 3 (L. D. S.) consisted of 4 1 boys with a urethral stent for 1 week who received adjunct caudal analgesia. Group 4 (P. H. M.) consisted of 73 boys with a urethral stent for 1 t o 3 days of whom 22 received caudal analgesia, 9 received a penile block and 42 received continuous postoperative epidural anesthesia for 1 to 2 days. Surgery was performed in groups 1 to 3 on a n outpatient basis and in group 4 on an inpatient basis. Followup was a t least 6 months. The meatal based modified Mathieu hypospadias repair was performed in a similar manner by all surgeons, as described in 1987 by Rabinowitz.” Optical loupes were used for magnification with attention to careful tissue handling and microsurgical technique. A running closure of the lateral aspects of the meatal based skin flap to the glans flap was
836
837
OUTCOME ANALYSIS OF MODIFIED MATHIEU REPAIR
done using polydioxanone, chromic catgut or polyglactin suture. The lateral glans flaps were then reapproximated in the midline over the neourethra using subcuticular sutures. There were no overlying suture lines. Repairs were tested to verify that they were watertight. In group 1all flap anastomoses were performed using 7-zero polydioxanone subcuticular suture. Closure was 1layer in 38 patients and 2 layers in 39. In this group of patients the second layer was done with interrupted subcuticular 7-Zero polydioxanone sutures. In group 2 the anastomoses were performed using 6-zero subcuticular chromic catgut as the first layer and continuous Y-ZerO polyglactin as the second layer. Repair was 1layer in 108 patients and 2 layers in 37. In Group 3 continuous 7-Zero polyglactin through-and-through suture was used in a 2-layer anastomosis in all 41 patients. In group 4 the anastomoses were performed using 6-zero polyglactin subcuticular continuous suture as the first layer and 7-Zero interrupted polyglactin as the second layer. Repair was 1layer in 67 patients and 2 layers in 6. A total of 152,l-layer and 184, 2-layer repairs were performed. We enumerated complications requiring medical intervention or surgical revision. Analysis of outcomes regarding fistula formation as well as overall complications was performed, comparing the stented and unstented groups. Outcomes of caudal analgesia and other forms of adjunct analgesia were compared. Outcomes after 1 and 2-layer repairs were also evaluated. Because of the small number of outcomes in each cell (less than 5), nonparametric statistical analysis was performed using the 2-tailed Fisher exact test and computer software. RESULTS
Excellent cosmetic and functional results were obtained in 325 of the 336 patients (96.7%). There were no cases of urinary retention. Complications occurred in 3 of the 77 patients (3.9%) in group 1, including a fistula in 1, meatal stenosis in 1 and meatal retraction in 1, which required repair. Complications in the 145 group 2 patients included 5 fistulas (3.4%). In group 3 a fistula developed in 2 of the 41 patients (4.9%). One of the 73 patients (1.4%)in group 4 had a fistula (table 1). There was no difference in the fistula or overall complication rate between the stented and unstented groups (table 2). A urethrocutaneous fistula occurred in 6 of the 222 patients (2.70%) without a urethral stent and in 3 of the 114 (2.63%) with a urethral stent (p >0.999). All fistulas except 1 were repaired successfully in 1stage. In 1patient in the unstented group meatal retraction developed, which required repeat modified Mathieu repair, and 1patient required meatotomy
TABLE2. Modified Mathieu reoairs No. Pts. Repair: Unstented Stented p Value* Adjunct analgesia: Caudal Penile blocktcontinuous epidural p Value' Repair with caudal analgesia: Unstented Stented p Value* No. layers: 1 2 D Value* * Fisher's exact test.
222 114 136 200
No. Fistulas (Ic) No. Comalications ( 8 )
6 (2.7) 3 (2.63) >0.999 3 6
(2.21) (3)
0.744
8 (3.6) 3 (2.63) 0.756 5 6
(3.67) (3)
0.762
73 63
1 (1.37) 2 (3.17) 0.596
3 (4.11) 2 (3.17) >0.999
152 184
5 (3.29) 4 (2.17) 0.737
6 (3.95) 5 (2.71) 0.554
for meatal stenosis for an overall complication rate of 3.60% (8 of 222) compared to 2.63% (3 of 114) in the stented group (p = 0.756). Caudal analgesia, a penile block and continuous epidural analgesia were subjectively found to be effective adjuncts for improved postoperative pain control. Outcomes of cases with and without caudal analgesia were compared (table 2). Fistulas occurred in 3 of the 136 patients (2.21%)who received adjunct caudal analgesia compared t o 6 of the 200 (3%) without caudal analgesia (p = 0.744). Of the patients given caudal analgesia meatal retraction and meatal stenosis developed in 1 each. Therefore, the overall complication rate was 3.67% (5 of 136 patients) in those who received caudal analgesia compared to 3% in those who received other adjunct analgesia (p = 0.762). Also, of the patients given caudal analgesia there was no difference in overall complication rates between stented and unstented repairs (3.17 versus 4.11%, respectively, p >0.999, table 2). One and 2-layer repairs were also compared (table 2). A fistula developed in 4 of the 184 patients (2.17%) with a 2-layer anastomosis and in 5 of the 152 (3.29%)with a 1-layer repair (p = 0.737). One patient with a 1-layer repair had meatal retraction for an overall complication rate of 3.95% compared to 2.71% in those with a 2-layer repair (p = 0.554). Patients who had complications were 6 to 66 months old (average age 29.2, table 1).The length of the meatal flap in patients with fistulas ranged from 10 t o 25 mm. DISCUSSION
TABLE1. Complications of the modified Mathieu repair Complication Group 1 (77pts., unstented, caudal analgesia): Fistula Meatal retraction Meatal stenosis Group 2 (145pts., unstented, penile block): Fistula Fistula Fistula Fistula Fistula Group 3 (41 pts., stented, caudal analgesia): Fistula Fistula Group 4 (73 pts., stented, continuous epidural analgesia): Fistula
Pt. Age (mos.)
Flap Length (mm.)
No. Layers
41 6 7
11 11 12
1 1 2
9 10 15 8 10
10 12 11 14 15
1 1 1 1
47 57
10 11
2 2
66
25
1
1
The modified Mathieu repair for distal hypospadias performed without a catheter on an outpatient basis has been shown to produce excellent results with few complications.'-4 In 1987 Rabinowitz reported good results with no fistulas and few complications in 59 patients who underwent the modified Mathieu repair without a catheter.' This series comprised a small number of patients who are not included in the 145 more recent patients in group 2. However, others recently reported a higher complication rate (18.9%) in repairs without the use of stents and, therefore, have advocated their use.5 There remains controversy as to the indications for urethral stents in Mathieu hypospadias repair.3-6 Therefore, we performed a retrospective study to test the complication rate for Mathieu hypospadias repair when performed with and without a stent, and compared the results among groups. The fistula and overall complication rates in the stented and unstented groups were not significantly different. The type of adjunct analgesia did not affect the outcome of surgery, and all types were subjectively believed to promote
838
OUTCOME ANALYSIS OF MODIFIED MATHIEU REPAIR
adequate postoperative pain control. Although caudal analgesia is thought to increase the risk of urinary retention and potentially the risk of urethrocutaneous fistula,” there were no cases of urinary retention, and we found similar complication rates in the groups with and without adjunct caudal analgesia. Also, of the patients who had caudal analgesia there was no improvement in outcome with a stent compared to without a stent (table 2). These findings are similar t o those of Zaontz, who reported no need for urinary diversion after caudal analgesia even in noncatheter repair.G Surgical technique was believed to be the most important aspect for success. Preserving the vasculature of the flap and avoiding overlapping suture lines are essential. As previously described by Kass and Bolong,7 2-layer closure is thought to produce superior anastomosis with a reduced risk of fistula formation. Although there were slightly lower complication rates in repairs performed in 2 layers compared to those with 1, both types of repair produced satisfactory results. As the authors gained experience with this type of repair, they extended the indications for this procedure using longer flaps,7 which may have contributed to the slightly higher fistula rate than that previously reported by Rabinowitz.2 A limitation of this series is the lack of statistical power. The number of complications in each cell (group) is too small to detect reliably statistically significant differences between stented and unstented repairs. Because of the relatively small percent of complications as well as the possibility that there are unknown differences among groups that may affect the results, a much larger sample size is required to detect differences in outcomes. To obtain a statistical power of 80%
with a type I error of 5% and showing a 50% difference a sample size of approximately 3,000 patients is required. However, in our retrospective observational study of 336 patients analysis of surgical outcomes shows no difference in fistula or complication rates between stented and unstented repairs. We found no increase in the fistula or complication rates in patients who received adjunct caudal analgesia. In conclusion, our data indicate that successful Mathieu repair is independent of the use of a urethral stent. Dr. Gerald T. OConnor and his staff provided statistical support. REFERENCES
1. Mathieu, P.: Traitment en un temps de l’hypospadias balanique ou juxtabalanique. J. Chir., 39: 481,1932. 2. Rabinowitz, R.: Outpatient catheterless modified Mathieu hypospadias repair. J. Urol., 138 1074, 1987. 3. McCormack, M., Homsy, Y. and Laberge, Y.: “NOstent, no diversion” Mathieu hypospadias repair. Canad. J. Surg., 3 6 152, 1993. 4. Wheeler, R. A., Malone, P. S., Griffths, D. M. and Burge, D. M.: The Mathieu operation. Is a urethral stent mandatory? Brit. J. Urol., 71: 492, 1993. 5. Buson, H., Smiley, D., Reinberg, Y. and Gonzalez, R.: Distal hypospadias repair without stents: is it better? J. Urol., 151: 1059, 1994. 6. Zaontz, M. R.: Nuances of hypospadias. Probl. Urol., 4: 705, 1990. 7. Kass, E. J. and Bolong, D.: Single stage hypospadias reconstruction without fistula. J. Urol., 144: 520, 1990.
THE JOURNAL
Vol. 156,836-838,August 1996 Printed in U.SA.
OF UROLoCY
Copyright 0 1996 by AMERICAS UROLOCICAL ASSOCIATION, IKC.
OUTCOME ANALYSIS OF THE MODIFIED MATHIEU HYPOSPADIAS REPAIR: COMPARISON OF STENTED AND UNSTENTED REPAIRS SAMUEL HAKIM, PAUL A. MERGUERIAN,* RONALD W I N O W I T Z , LINDA D. SHORTLIFFE PATRICK H. McKENNA
AND
From the Department of Surgery, Section of Urology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, Department of Urology. Division of Pediatric Urology, Stanford University Medical Center, Stanford, California, and Departments of Urology, University of Rochester Medical Center, Rochester, New York, and Naval Regional Medical Center, Portsmouth, Virginia
ABSTRACT
Purpose: We compared surgical outcomes of stented and unstented Mathieu repairs in boys with primary distal hypospadias, and evaluated the efficacy and safety of caudal analgesia relative to other forms of analgesia (penile block and epidural analgesia). Materials and Methods: We retrospectively reviewed the records of 336 consecutive boys who underwent the modified Mathieu repair for primary distal hypospadias. A urethral stent was placed in 114 patients and nonstented repair was performed in 222. Adjunct caudal analgesia was given in 136 cases, a penile block in 158 and continuous epidural analgesia in 42. Results: None of the unstented cases had urinary retention. Analysis of surgical outcomes revealed no difference in fistula formation between patients with and without stents (2.63 versus 2.70%,respectively, p ~3.999).Overall complication rates in the stented and unstented groups were not significantly different (2.63 versus 3.60%,respectively, p = 0.756). The fistula rate in patients who received adjunct caudal analgesia was no different than in those who received other forms of adjunct analgesia (2.21 versus 3.0%,respectively, p >0.999). Conclusions: These data suggest that successful Mathieu hypospadias repair is independent of the use of a stent. Caudal analgesia, a penile block and epidural analgesia provided effective postoperative pain control with no difference in complication rates. To our knowledge our report represents the largest observational study reported to date comparing stented and unstented repairs. However, because of the small number of complications in each group, a much larger study is required to determine statistically significant differences among these groups. KEY WORDS:penis, hypospadias, stents, complications, analgesia
The Mathieu repair for primary distal hypospadias has been shown to be safe and effective when performed without catheter drainage on an outpatient basis.’-4 In his initial series of meatal based flap repair for distal hypospadias Mathieu did not use catheter drainage.’ In 1987 Rabinowitz reported excellent results in his series of outpatient noncatheter hypospadias repair using a modification of the Mathieu technique.2 Others have reported similar findings.3.4 Significant morbidity has been associated with urethral stents, including infection, bladder spasm and migration. Nevertheless, despite these findings there remains disagreement on the need for urethral catheters or stents in primary hypospadias repair.s5 Recently Buson et a1 reported a n 18.9%complication rate (13.5%fistula rate) in unstented Mathieu repairs compared to a 4.6%complication rate (1.5% fistula rate) when a stent was used.5 They concluded that a urethral stent was advantageous, and believed that the short-term use of a stent should be considered standard for meatal based flaps.5 However, Rabinowitz noted other potential etiologies for the higher fistula rate in the unstented group, including meatal stenosis and postoperative urethral manipulation for urinary retention.5 Also, caudal analgesia is thought to increase the risk of urinary retention and potentially the risk of urethrocutaneous fistula.5 Therefore, we The opinions and assertions contained herein are the private views of the authors and are not to be construed as reflecting the views of the United States Navy, Air Force or De artment of Defense. * Requests for reprints: Department o!Urology, Division of Pediatric Urology, Stanford University Medical Center, Stanford, California 94305.
performed a multi-institutional retrospective study to compare complication rates in the modified Mathieu repair performed with and without a catheter as well as the results of caudal analgesia, and penile and continuous epidural blocks. Outcomes after 1 and 2-layer repairs were also evaluated. SUBJECTS AND METHODS
A total of 336 consecutive boys 5 months to 13 years old (average age 19.9 months) underwent the modified Mathieu repair for primary distal penile hypospadias at 4 institutions. Four groups were analyzed from 4 pediatric urologists. Group 1 (P.A.M.) consisted of 77 boys who underwent Mathieu repair without a urethral stent of whom 73 received adjunct caudal analgesia and 4 received a penile block. Group 2 (R. R.) consisted of 145 boys without a urethral stent who received a penile block. Group 3 (L. D. S.) consisted of 4 1 boys with a urethral stent for 1 week who received adjunct caudal analgesia. Group 4 (P. H. M.) consisted of 73 boys with a urethral stent for 1 t o 3 days of whom 22 received caudal analgesia, 9 received a penile block and 42 received continuous postoperative epidural anesthesia for 1 to 2 days. Surgery was performed in groups 1 to 3 on a n outpatient basis and in group 4 on an inpatient basis. Followup was a t least 6 months. The meatal based modified Mathieu hypospadias repair was performed in a similar manner by all surgeons, as described in 1987 by Rabinowitz.” Optical loupes were used for magnification with attention to careful tissue handling and microsurgical technique. A running closure of the lateral aspects of the meatal based skin flap to the glans flap was
836
837
OUTCOME ANALYSIS OF MODIFIED MATHIEU REPAIR
done using polydioxanone, chromic catgut or polyglactin suture. The lateral glans flaps were then reapproximated in the midline over the neourethra using subcuticular sutures. There were no overlying suture lines. Repairs were tested to verify that they were watertight. In group 1all flap anastomoses were performed using 7-zero polydioxanone subcuticular suture. Closure was 1layer in 38 patients and 2 layers in 39. In this group of patients the second layer was done with interrupted subcuticular 7-Zero polydioxanone sutures. In group 2 the anastomoses were performed using 6-zero subcuticular chromic catgut as the first layer and continuous Y-ZerO polyglactin as the second layer. Repair was 1layer in 108 patients and 2 layers in 37. In Group 3 continuous 7-Zero polyglactin through-and-through suture was used in a 2-layer anastomosis in all 41 patients. In group 4 the anastomoses were performed using 6-zero polyglactin subcuticular continuous suture as the first layer and 7-Zero interrupted polyglactin as the second layer. Repair was 1layer in 67 patients and 2 layers in 6. A total of 152,l-layer and 184, 2-layer repairs were performed. We enumerated complications requiring medical intervention or surgical revision. Analysis of outcomes regarding fistula formation as well as overall complications was performed, comparing the stented and unstented groups. Outcomes of caudal analgesia and other forms of adjunct analgesia were compared. Outcomes after 1 and 2-layer repairs were also evaluated. Because of the small number of outcomes in each cell (less than 5), nonparametric statistical analysis was performed using the 2-tailed Fisher exact test and computer software. RESULTS
Excellent cosmetic and functional results were obtained in 325 of the 336 patients (96.7%). There were no cases of urinary retention. Complications occurred in 3 of the 77 patients (3.9%) in group 1, including a fistula in 1, meatal stenosis in 1 and meatal retraction in 1, which required repair. Complications in the 145 group 2 patients included 5 fistulas (3.4%). In group 3 a fistula developed in 2 of the 41 patients (4.9%). One of the 73 patients (1.4%)in group 4 had a fistula (table 1). There was no difference in the fistula or overall complication rate between the stented and unstented groups (table 2). A urethrocutaneous fistula occurred in 6 of the 222 patients (2.70%) without a urethral stent and in 3 of the 114 (2.63%) with a urethral stent (p >0.999). All fistulas except 1 were repaired successfully in 1stage. In 1patient in the unstented group meatal retraction developed, which required repeat modified Mathieu repair, and 1patient required meatotomy
TABLE2. Modified Mathieu reoairs No. Pts. Repair: Unstented Stented p Value* Adjunct analgesia: Caudal Penile blocktcontinuous epidural p Value' Repair with caudal analgesia: Unstented Stented p Value* No. layers: 1 2 D Value* * Fisher's exact test.
222 114 136 200
No. Fistulas (Ic) No. Comalications ( 8 )
6 (2.7) 3 (2.63) >0.999 3 6
(2.21) (3)
0.744
8 (3.6) 3 (2.63) 0.756 5 6
(3.67) (3)
0.762
73 63
1 (1.37) 2 (3.17) 0.596
3 (4.11) 2 (3.17) >0.999
152 184
5 (3.29) 4 (2.17) 0.737
6 (3.95) 5 (2.71) 0.554
for meatal stenosis for an overall complication rate of 3.60% (8 of 222) compared to 2.63% (3 of 114) in the stented group (p = 0.756). Caudal analgesia, a penile block and continuous epidural analgesia were subjectively found to be effective adjuncts for improved postoperative pain control. Outcomes of cases with and without caudal analgesia were compared (table 2). Fistulas occurred in 3 of the 136 patients (2.21%)who received adjunct caudal analgesia compared t o 6 of the 200 (3%) without caudal analgesia (p = 0.744). Of the patients given caudal analgesia meatal retraction and meatal stenosis developed in 1 each. Therefore, the overall complication rate was 3.67% (5 of 136 patients) in those who received caudal analgesia compared to 3% in those who received other adjunct analgesia (p = 0.762). Also, of the patients given caudal analgesia there was no difference in overall complication rates between stented and unstented repairs (3.17 versus 4.11%, respectively, p >0.999, table 2). One and 2-layer repairs were also compared (table 2). A fistula developed in 4 of the 184 patients (2.17%) with a 2-layer anastomosis and in 5 of the 152 (3.29%)with a 1-layer repair (p = 0.737). One patient with a 1-layer repair had meatal retraction for an overall complication rate of 3.95% compared to 2.71% in those with a 2-layer repair (p = 0.554). Patients who had complications were 6 to 66 months old (average age 29.2, table 1).The length of the meatal flap in patients with fistulas ranged from 10 t o 25 mm. DISCUSSION
TABLE1. Complications of the modified Mathieu repair Complication Group 1 (77pts., unstented, caudal analgesia): Fistula Meatal retraction Meatal stenosis Group 2 (145pts., unstented, penile block): Fistula Fistula Fistula Fistula Fistula Group 3 (41 pts., stented, caudal analgesia): Fistula Fistula Group 4 (73 pts., stented, continuous epidural analgesia): Fistula
Pt. Age (mos.)
Flap Length (mm.)
No. Layers
41 6 7
11 11 12
1 1 2
9 10 15 8 10
10 12 11 14 15
1 1 1 1
47 57
10 11
2 2
66
25
1
1
The modified Mathieu repair for distal hypospadias performed without a catheter on an outpatient basis has been shown to produce excellent results with few complications.'-4 In 1987 Rabinowitz reported good results with no fistulas and few complications in 59 patients who underwent the modified Mathieu repair without a catheter.' This series comprised a small number of patients who are not included in the 145 more recent patients in group 2. However, others recently reported a higher complication rate (18.9%) in repairs without the use of stents and, therefore, have advocated their use.5 There remains controversy as to the indications for urethral stents in Mathieu hypospadias repair.3-6 Therefore, we performed a retrospective study to test the complication rate for Mathieu hypospadias repair when performed with and without a stent, and compared the results among groups. The fistula and overall complication rates in the stented and unstented groups were not significantly different. The type of adjunct analgesia did not affect the outcome of surgery, and all types were subjectively believed to promote
838
OUTCOME ANALYSIS OF MODIFIED MATHIEU REPAIR
adequate postoperative pain control. Although caudal analgesia is thought to increase the risk of urinary retention and potentially the risk of urethrocutaneous fistula,” there were no cases of urinary retention, and we found similar complication rates in the groups with and without adjunct caudal analgesia. Also, of the patients who had caudal analgesia there was no improvement in outcome with a stent compared to without a stent (table 2). These findings are similar t o those of Zaontz, who reported no need for urinary diversion after caudal analgesia even in noncatheter repair.G Surgical technique was believed to be the most important aspect for success. Preserving the vasculature of the flap and avoiding overlapping suture lines are essential. As previously described by Kass and Bolong,7 2-layer closure is thought to produce superior anastomosis with a reduced risk of fistula formation. Although there were slightly lower complication rates in repairs performed in 2 layers compared to those with 1, both types of repair produced satisfactory results. As the authors gained experience with this type of repair, they extended the indications for this procedure using longer flaps,7 which may have contributed to the slightly higher fistula rate than that previously reported by Rabinowitz.2 A limitation of this series is the lack of statistical power. The number of complications in each cell (group) is too small to detect reliably statistically significant differences between stented and unstented repairs. Because of the relatively small percent of complications as well as the possibility that there are unknown differences among groups that may affect the results, a much larger sample size is required to detect differences in outcomes. To obtain a statistical power of 80%
with a type I error of 5% and showing a 50% difference a sample size of approximately 3,000 patients is required. However, in our retrospective observational study of 336 patients analysis of surgical outcomes shows no difference in fistula or complication rates between stented and unstented repairs. We found no increase in the fistula or complication rates in patients who received adjunct caudal analgesia. In conclusion, our data indicate that successful Mathieu repair is independent of the use of a urethral stent. Dr. Gerald T. OConnor and his staff provided statistical support. REFERENCES
1. Mathieu, P.: Traitment en un temps de l’hypospadias balanique ou juxtabalanique. J. Chir., 39: 481,1932. 2. Rabinowitz, R.: Outpatient catheterless modified Mathieu hypospadias repair. J. Urol., 138 1074, 1987. 3. McCormack, M., Homsy, Y. and Laberge, Y.: “NOstent, no diversion” Mathieu hypospadias repair. Canad. J. Surg., 3 6 152, 1993. 4. Wheeler, R. A., Malone, P. S., Griffths, D. M. and Burge, D. M.: The Mathieu operation. Is a urethral stent mandatory? Brit. J. Urol., 71: 492, 1993. 5. Buson, H., Smiley, D., Reinberg, Y. and Gonzalez, R.: Distal hypospadias repair without stents: is it better? J. Urol., 151: 1059, 1994. 6. Zaontz, M. R.: Nuances of hypospadias. Probl. Urol., 4: 705, 1990. 7. Kass, E. J. and Bolong, D.: Single stage hypospadias reconstruction without fistula. J. Urol., 144: 520, 1990.