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Predicting risk factors for inguinal hernia after radical retropubic prostatectomy
ADULT UROLOGY
PREDICTING RISK FACTORS FOR INGUINAL HERNIA AFTER RADICAL RETROPUBIC PROSTATECTOMY CHIA-MING TWU, YEN-CHUAN OU, CHI-REI YANG, CHEN-LI CHENG, and HAO-CHUNG HO
ABSTRACT Objectives. To determine the risk factors for postprostatectomy inguinal hernia development. Methods. From January 1998 to June 2004, we investigated the medical records of 201 consecutive patients who had undergone radical retropubic prostatectomy. Postoperatively, 25 (12.4%) of 201 patients developed an inguinal hernia. The preoperative factors, including age, presence of diabetes mellitus, smoking, and previous unilateral hernioplasty, of this group were compared with those of the 176 patients who did not develop an inguinal hernia. The postoperative parameters, including pathologic stage, specimen weight, adjuvant radiotherapy, and postoperative wound-related problems, were compared between the two groups. Results. The patients who had undergone previous unilateral hernioplasty developed a groin hernia after prostatectomy more frequently than those who did not (P ⫽ 0.001, Fisher’s exact test). Additionally, once a postoperative wound-related problem occurred, the incidence of postprostatectomy groin hernia increased substantially (P ⫽ 0.025, logistic regression analysis). Conclusions. We suggest routine repair of the contralateral groin for patients who have undergone previous unilateral hernioplasty. Prevention of wound-related problems appears to decrease the incidence of postprostatectomy groin hernias. UROLOGY 66: 814–818, 2005. © 2005 Elsevier Inc.
I
n the modern prostate-specific antigen (PSA) era, prostate cancer has become the most commonly diagnosed cancer among American men, with a downstage deviation.1,2 The number of patients who undergo radical retropubic prostatectomy (RRP) has increased substantially during the past decade. The surgical-related mortality rate has been low, and the postoperative complications have been mostly wound related.3 The major serious side effects, such as urinary incontinence and erectile dysfunction, are well established.4,5 Nonetheless, although Regan et al.6 were the first to describe the relationship between RRP and postprostatectomy inguinal hernia formation in 1996, the factors leading to From the Division of Urology, Department of Surgery, Taichung Veterans General Hospital, National Yang-Ming University School of Medicine, Taichung; Institute of Medicine, Chung Shan Medical University, Taichung; Graduate Institute of Biomedicine and Biomedical Technology and Department of Applied Chemistry, National Chi Nan University, Nantou, Taiwan Reprint requests: Yen-Chuan Ou, M.D., Ph.D., Division of Urology, Department of Surgery, Taichung Veterans General Hospital, 160 Section 3, Taichung-Kang Road, Taichung 40705, Taiwan. E-mail: [email protected] Submitted: January 25, 2005, accepted (with revisions): April 19, 2005 © 2005 ELSEVIER INC. 814
ALL RIGHTS RESERVED
hernia formation warrant further study. We investigated the preoperative predisposing factors and postoperative parameters that influence the occurrence of postprostatectomy inguinal hernia to predict the possibility of its occurrence and prevent its development.
MATERIAL AND METHODS Between January 1998 and June 2004, we investigated the medical records of 201 consecutive patients who had undergone RRP. Because Regan et al.6 had stated the relationship between RRP and postprostatectomy inguinal hernia formation, all the patients who had been advised to undergo RRP at our hospital had specific medical information recorded on their chart. The information included the preoperative condition, such as comorbidities, operative history, age, and postoperative status, such as postoperative radiotherapy, wound-related problems, groin condition, and so forth. Of the 201 patients, 25 (12.4%) developed a postprostatectomy inguinal hernia. All patients were followed up regularly. Usually, it was the examiner who found the groin hernia. The site of the hernia was on the right in 14 patients (56%), left in 8 patients (32%), and bilateral in 3 patients (12%). The hernia type was indirect in 21 (84%) and direct in 4 (16%). The timing of hernia occurrence after RRP ranged from 1 to 23 months (mean 9.36). 0090-4295/05/$30.00 doi:10.1016/j.urology.2005.04.034
TABLE I. Preoperative factors between patients with and without hernia Hernia Yes (n ⴝ 25)
Clinical Characteristic Age (yr) Mean ⫾ SD 95% CI Diabetes mellitus Yes No Hypertension with or without CAD Yes No Smoking with or without COPD Yes No Previous unilateral hernioplasty Yes No
No (n ⴝ 176)
P Value 0.502*
70.36 ⫾ 4.93 68.32–72.40
69.59 ⫾ 5.28 68.81–70.38
0 (0.0) 25 (100.0)
20 (11.4) 156 (88.6)
9 (36.0) 16 (64.0)
68 (38.6) 108 (61.4)
0.143†
0.973‡
0.172‡ 15 (60.0) 10 (40.0)
76 (43.2) 100 (56.8) 0.001†§
7 (28.0) 18 (72.0)
8 (4.5) 168 (95.5)
KEY: SD ⫽ standard deviation; CI ⫽ confidence interval; CAD ⫽ coronary artery disease; COPD ⫽ chronic obstructive pulmonary disease. Data presented as number of patients, with percentages in parentheses, unless otherwise noted. * Mann-Whitney U test. † Fisher’s exact test. ‡ Yates correction of contigency. § P ⬍0.01.
A computerized database was created, and data were abstracted directly from the patients’ records. The information abstracted and entered included preoperative predisposing factors such as age, smoking (with or without chronic obstructive pulmonary disease), diabetes mellitus, and previous unilateral hernioplasty.7–9 The postoperative parameters included pathologic prostate cancer stage, resected specimen weight, wound-related complications, and use of adjuvant radiotherapy. The pathologic stage was divided into two groups, organ-confined disease and extracapsular extension.10 Organconfined disease was defined as the tumor being confined within the prostatic capsule, with no seminal vesicle or lymph node involvement. Extracapsular extension was defined as tumor perforation of the prostatic capsule, extending entirely through the capsule. Wound-related complications included wound infection, wound dehiscence, seroma formation, and persistent lymph leakage for more than 10 days. The statistically significant differences were analyzed using the Mann-Whitney U test, Fisher’s exact test, and Yates correction for contingency in primary data. Multivariate survival analyses were performed for selected parameters using the Scientific Package for Social Sciences (version 10.1, SPSS, Chicago, Ill) Cox program (logistic regression backward stepwise model); the P values were assessed using the Wald statistic. The operative procedure at our hospital used the standard Walsh procedure. A low midline incision was done and bilateral pelvic lymphadenectomy was performed initially. Some suspected lesions were sent for frozen section examination first, with bilateral pelvic lymphadenectomy performed completely thereafter. If the result of the frozen section analysis was positive, the procedure was completed and no RRP was done. These patients were excluded from our series. If the findings were negative, RRP was performed using the standard Walsh procedure.
RESULTS During the follow-up period after RRP, hernias developed in 25 patients, and none developed in UROLOGY 66 (4), 2005
176 patients. The follow-up periods were similar for both groups (35.06 ⫾ 18.23 months for the hernia group and 29.52 ⫾ 20.67 months for the no-hernia group, P ⫽ 0.127). The preoperative predisposing factors selected for comparison between the two groups were diabetes mellitus, hypertension (with or without coronary artery disease), smoking (with or without chronic obstructive pulmonary disease), and previous unilateral hernioplasty (Table I).11 A significantly greater percentage of patients in the hernia group had undergone previous unilateral hernioplasty than those in the no-hernia group (P ⫽ 0.001). The results from the multivariate analysis of the variables using the logistic regression backward stepwise model are shown in Table II. The odds ratio of previous unilateral hernioplasty was 9.30 (95% confidence interval 2.80 to 30.87, P ⫽ 0.003). Thus, patients who had undergone previous hernioplasty were nine times more likely to develop a post-RRP hernia. Table III shows the comparisons between the two groups according to the postoperative factors such as pathologic stage, specimen weight, use of adjuvant radiotherapy, and postoperative woundrelated complications. Once a wound-related complication occurred, the incidence of hernia formation increased (P ⫽ 0.056). This relationship was examined using logistic regression analysis (Table IV). The odds ratio for wound-related morbidity was 4.935 (95% confidence interval 1.2223 to 19.9257; P ⫽ 0.025). 815
TABLE II. Logistic regression analysis for preoperative factors between two groups Variable
Regression Coefficient
SE
Odds Ratio
95% CI of Odds Ratio
P Value
⫺0.035 7.323 0.115 0.804 2.230 1.910
0.047 21.619 0.487 0.472 0.612 3.265
0.966 1514.739 1.122 2.234 9.299 6.755
0.8816–1.0579 0.0000–3.83E ⫹ 21 0.4321–2.9118 0.8865–5.6309 2.8014–30.8703
0.4535 0.7348 0.8134 0.0883 0.0003* 0.5585
Age Diabetes mellitus (⫹) Hypertension with or without CAD (⫹) Smoking with or without COPD (⫹) Previous unilateral hernioplasty (⫹) Constant KEY: SE ⫽ standard error; other abbreviations as in Table I. * P ⬍0.05 (tested by Wald statistic).
TABLE III. Postoperative factors between patients with and without hernia Hernia Yes (n ⴝ 25)
No (n ⴝ 176)
14.76 ⫾ 6.02 12.28–17.24
13.93 ⫾ 6.99 12.89–14.97
52.28 ⫾ 24.06 42.35–62.21
48.43 ⫾ 28.18 44.23–52.62
Clinical Characteristic Hospitalization stay (days) Mean ⫾ SD 95% CI Specimen (g) Mean ⫾ SD 95% CI Wound-related problem Yes No Adjuvant radiotherapy Yes No Stage Organ-confined disease Extracapsular extension Follow-up (mo) Mean ⫾ SD 95% CI
P Value 0.334*
0.233*
0.056† 7 (28.0) 18 (72.0)
21 (11.9) 155 (88.1)
1 (4.0) 24 (96.0)
20 (11.4) 156 (88.6)
0.482†
0.767‡ 6 (24.0) 19 (76.0)
51 (29.1) 124 (70.9) 0.127*
35.06 ⫾ 18.23 27.54–42.58
29.52 ⫾ 20.67 26.45–32.60
Abbreviations as in Table I. Data presented as number of patients, with percentages in parentheses, unless otherwise noted. * Mann-Whitney U test. † Fisher’s exact test. ‡ Yates correction of contigency.
TABLE IV. Logistic regression analysis for postoperative factors between two groups Variable Hospitalization stay (days) Specimen (g) Wound-related problem (⫹) Adjuvant radiotherapy (⫹) Stage (ECE) Constant
Regression Coefficient
SE
Odds Ratio
95% CI of Odds Ratio
P Value
0.046 ⫺0.007 1.596 1.542 0.751 0.810
0.051 0.007 0.712 1.086 0.545 1.239
1.047 0.993 4.935 4.676 2.119 2.248
0.9477–1.1571 0.9786–1.0072 1.2223–19.9257 0.5561–39.3207 0.7275–6.1693
0.3653 0.3233 0.0250* 0.1556 0.1686 0.5134
KEY: SE ⫽ standard error; CI ⫽ confidence interval; ECE ⫽ extracapsular extension. * P ⬍0.05 (tested by Wald statistic).
COMMENT Although Regan et al.6 introduced the relationship between inguinal hernia formation and RRP in 1996, the etiology of post-RRP inguinal hernia is 816
still poorly understood. The “shutter mechanism,” a U-shaped internal ring that acts as a valve, is believed to be the barrier preventing hernia formation.6 Regan et al.6 stated that, during RRP, a small UROLOGY 66 (4), 2005
defect in the inguinal ring is unwittingly enlarged secondary to the prolonged stretching of the rectus and lower abdominal musculature. We tried to use the pathologic stage and specimen weight as substitutes for the dissection and stretching during RRP to demonstrate that the greater the muscular stretching, the greater the internal ring destruction, and thus the greater the incidence of hernia formation. However, we failed to show any such relationship between pathologic stage and specimen weight and hernia formation (P ⫽ 0.17 for pathologic stage and P ⫽ 0.32 for specimen weight). Lodding et al.9 confirmed the relationship between RRP and inguinal hernia by comparing the incidence of inguinal hernia formation between post-RRP patients and those who had not undergone RRP. They noted that previous unilateral hernioplasty played an important role in the formation of inguinal hernia after RRP. We studied 15 patients with a history of unilateral hernioplasty, and almost 50% (7 of 15) developed a contralateral inguinal hernia after undergoing RRP (P ⫽ 0.001, Fisher’s exact test). Therefore, should we strengthen the contralateral groin simultaneously when we perform RRP in patients who have undergone previous unilateral hernioplasty? Regan et al.6 suggested that urologists should consider repairing any inguinal weakness in the inguinal floor or inguinal ring at RRP. Schlegel and Walsh reported repairing any defect in the inguinal floor or ring while awaiting the frozen section analysis results of pelvic lymph node dissection.6 In Japan, Arai et al.3 reported very low morbidity and mortality after RRP. In their research, the surgical mortality was very low (0.16%), similar to the surgical mortality rate (1 of 201) among our patients. The most common complications we encountered were wound-related complications (7.5%) and anastomotic leakage (4.1%). When we compared our hernia group with our no-hernia group for wound-related problems, 28 patients had postRRP wound problems and these patients had a greater rate of inguinal hernia formation than did the group without wound-related problems. The difference between the groups was statistically significant by the regression backward stepwise method (Table IV). These data suggest that we should examine the groin carefully after RRP, especially among those with postoperative woundrelated problems. Prevention of wound-related problems during RRP may be of significant benefit in decreasing the incidence of post-RRP inguinal hernia. Lodding et al.9 also discussed the formation of postoperative anastomosis stricture, which seemed to be associated with an increased incidence of UROLOGY 66 (4), 2005
groin hernia. Among our patients, only three had significant stricture recorded in their medical records, and all need further management. One of these patients later developed an inguinal hernia, but, because of the small sample size, it was not analyzed in our study.
CONCLUSIONS We suggest that routine repair of the contralateral groin for patients who have undergone previous unilateral hernioplasty could be beneficial for preventing inguinal hernia formation after RRP. Preperitoneal repair of the contralateral groin or the Pfannenstiel incision for concurrent surgery can be done while waiting for the frozen section analysis data.12,13 A prospective randomized study will be done in the future to compare repair with nonrepair of contralateral groin for prevention of contralateral hernia after RRP. Definitely, in patients who developed postoperative wound-related problems, the incidence of postprostatectomy inguinal hernia increased. Prevention of wound-related problems during RRP appeared to decrease postoperative inguinal hernia formation.
REFERENCES 1. Ellis WJ, Chetner MP, Preston SD, et al: Diagnosis of prostatic carcinoma: the yield of serum prostate specific antigen, digital rectal examination and transrectal ultrasonography. J Urol 152: 1520 –1525, 1994. 2. Landis SH, Murray T, Bolden S, et al: Cancer statistics, 1998. Cancer J Clin 48: 6 –29, 1998. 3. Arai Y, Egawa S, Ogawa S, et al: Radical retropubic prostatectomy: time trends, morbidity and mortality in Japan. BJU Int 85: 287–294, 2000. 4. Hautmann RE, Sauter TW, and Wenderoth UK: Radical retropubic prostatectomy: morbidity and urinary continence in 418 consecutive cases. Urology 43: 47–51, 1994. 5. Fowler FJ, Barry MJ, Lu-Yao G, et al: Patient-reported complications and follow-up treatment after radical prostatectomy. Urology 42: 622– 629, 1993. 6. Regan TC, Mordkin RM, Constantinople NL, et al: Incidence of inguinal hernias following radical retropubic prostatectomy. Urology 47: 536 –537, 1996. 7. Liem MS, van der Graaf Y, Zwart RC, et al, for the Coala Trial Group: Risk factors for inguinal hernia in women, a case-control study. Am J Epidemiol 146: 721–726, 1997. 8. Sorensen LT, Friis E, Kjaergaard J, et al: Smoking is a risk factor for recurrence of groin hernia. World J Surg 26: 397– 400, 2002. 9. Lodding P, Bergdahl C, Hugosson J, et al: Inguinal hernia after radical retropubic prostatectomy for prostate cancer: a study of incidence and risk factors in comparison to no operation and lymphadenectomy. J Urol 166: 964 –967, 2001. 817
10. Ou YC, Chen JT, Yang CR, et al: Predicating prostate specific antigen failure after radical retropubic prostatectomy for T1c prostate cancer. Jpn J Clin Oncol 23: 536 – 542, 2002. 11. Zieren J, Zieren HU, Muller JM, et al: Repair of inguinal hernia in the elderly: results of the plug-and-patch repair with special reference to quality of life. Chirurg 71: 564 –567, 2000.
818
12. Stoppa RE, and Warlamount CR: The midline preperitoneal approach and prosthetic repair of groin hernia, in Nyhuis LH, and Baker RJ (Eds): Mastery of Surgery, 2nd ed. Boston, Little Brown, 1992, pp 1615–1624. 13. Manoharan M, Gomez P, and Soloway MS: Concurrent radical retropubic prostatectomy and inguinal hernia repair through a modified Pfannenstiel incision. Urol Oncol 93: 1203–1206, 2004.
UROLOGY 66 (4), 2005
PREDICTING RISK FACTORS FOR INGUINAL HERNIA AFTER RADICAL RETROPUBIC PROSTATECTOMY CHIA-MING TWU, YEN-CHUAN OU, CHI-REI YANG, CHEN-LI CHENG, and HAO-CHUNG HO
ABSTRACT Objectives. To determine the risk factors for postprostatectomy inguinal hernia development. Methods. From January 1998 to June 2004, we investigated the medical records of 201 consecutive patients who had undergone radical retropubic prostatectomy. Postoperatively, 25 (12.4%) of 201 patients developed an inguinal hernia. The preoperative factors, including age, presence of diabetes mellitus, smoking, and previous unilateral hernioplasty, of this group were compared with those of the 176 patients who did not develop an inguinal hernia. The postoperative parameters, including pathologic stage, specimen weight, adjuvant radiotherapy, and postoperative wound-related problems, were compared between the two groups. Results. The patients who had undergone previous unilateral hernioplasty developed a groin hernia after prostatectomy more frequently than those who did not (P ⫽ 0.001, Fisher’s exact test). Additionally, once a postoperative wound-related problem occurred, the incidence of postprostatectomy groin hernia increased substantially (P ⫽ 0.025, logistic regression analysis). Conclusions. We suggest routine repair of the contralateral groin for patients who have undergone previous unilateral hernioplasty. Prevention of wound-related problems appears to decrease the incidence of postprostatectomy groin hernias. UROLOGY 66: 814–818, 2005. © 2005 Elsevier Inc.
I
n the modern prostate-specific antigen (PSA) era, prostate cancer has become the most commonly diagnosed cancer among American men, with a downstage deviation.1,2 The number of patients who undergo radical retropubic prostatectomy (RRP) has increased substantially during the past decade. The surgical-related mortality rate has been low, and the postoperative complications have been mostly wound related.3 The major serious side effects, such as urinary incontinence and erectile dysfunction, are well established.4,5 Nonetheless, although Regan et al.6 were the first to describe the relationship between RRP and postprostatectomy inguinal hernia formation in 1996, the factors leading to From the Division of Urology, Department of Surgery, Taichung Veterans General Hospital, National Yang-Ming University School of Medicine, Taichung; Institute of Medicine, Chung Shan Medical University, Taichung; Graduate Institute of Biomedicine and Biomedical Technology and Department of Applied Chemistry, National Chi Nan University, Nantou, Taiwan Reprint requests: Yen-Chuan Ou, M.D., Ph.D., Division of Urology, Department of Surgery, Taichung Veterans General Hospital, 160 Section 3, Taichung-Kang Road, Taichung 40705, Taiwan. E-mail: [email protected] Submitted: January 25, 2005, accepted (with revisions): April 19, 2005 © 2005 ELSEVIER INC. 814
ALL RIGHTS RESERVED
hernia formation warrant further study. We investigated the preoperative predisposing factors and postoperative parameters that influence the occurrence of postprostatectomy inguinal hernia to predict the possibility of its occurrence and prevent its development.
MATERIAL AND METHODS Between January 1998 and June 2004, we investigated the medical records of 201 consecutive patients who had undergone RRP. Because Regan et al.6 had stated the relationship between RRP and postprostatectomy inguinal hernia formation, all the patients who had been advised to undergo RRP at our hospital had specific medical information recorded on their chart. The information included the preoperative condition, such as comorbidities, operative history, age, and postoperative status, such as postoperative radiotherapy, wound-related problems, groin condition, and so forth. Of the 201 patients, 25 (12.4%) developed a postprostatectomy inguinal hernia. All patients were followed up regularly. Usually, it was the examiner who found the groin hernia. The site of the hernia was on the right in 14 patients (56%), left in 8 patients (32%), and bilateral in 3 patients (12%). The hernia type was indirect in 21 (84%) and direct in 4 (16%). The timing of hernia occurrence after RRP ranged from 1 to 23 months (mean 9.36). 0090-4295/05/$30.00 doi:10.1016/j.urology.2005.04.034
TABLE I. Preoperative factors between patients with and without hernia Hernia Yes (n ⴝ 25)
Clinical Characteristic Age (yr) Mean ⫾ SD 95% CI Diabetes mellitus Yes No Hypertension with or without CAD Yes No Smoking with or without COPD Yes No Previous unilateral hernioplasty Yes No
No (n ⴝ 176)
P Value 0.502*
70.36 ⫾ 4.93 68.32–72.40
69.59 ⫾ 5.28 68.81–70.38
0 (0.0) 25 (100.0)
20 (11.4) 156 (88.6)
9 (36.0) 16 (64.0)
68 (38.6) 108 (61.4)
0.143†
0.973‡
0.172‡ 15 (60.0) 10 (40.0)
76 (43.2) 100 (56.8) 0.001†§
7 (28.0) 18 (72.0)
8 (4.5) 168 (95.5)
KEY: SD ⫽ standard deviation; CI ⫽ confidence interval; CAD ⫽ coronary artery disease; COPD ⫽ chronic obstructive pulmonary disease. Data presented as number of patients, with percentages in parentheses, unless otherwise noted. * Mann-Whitney U test. † Fisher’s exact test. ‡ Yates correction of contigency. § P ⬍0.01.
A computerized database was created, and data were abstracted directly from the patients’ records. The information abstracted and entered included preoperative predisposing factors such as age, smoking (with or without chronic obstructive pulmonary disease), diabetes mellitus, and previous unilateral hernioplasty.7–9 The postoperative parameters included pathologic prostate cancer stage, resected specimen weight, wound-related complications, and use of adjuvant radiotherapy. The pathologic stage was divided into two groups, organ-confined disease and extracapsular extension.10 Organconfined disease was defined as the tumor being confined within the prostatic capsule, with no seminal vesicle or lymph node involvement. Extracapsular extension was defined as tumor perforation of the prostatic capsule, extending entirely through the capsule. Wound-related complications included wound infection, wound dehiscence, seroma formation, and persistent lymph leakage for more than 10 days. The statistically significant differences were analyzed using the Mann-Whitney U test, Fisher’s exact test, and Yates correction for contingency in primary data. Multivariate survival analyses were performed for selected parameters using the Scientific Package for Social Sciences (version 10.1, SPSS, Chicago, Ill) Cox program (logistic regression backward stepwise model); the P values were assessed using the Wald statistic. The operative procedure at our hospital used the standard Walsh procedure. A low midline incision was done and bilateral pelvic lymphadenectomy was performed initially. Some suspected lesions were sent for frozen section examination first, with bilateral pelvic lymphadenectomy performed completely thereafter. If the result of the frozen section analysis was positive, the procedure was completed and no RRP was done. These patients were excluded from our series. If the findings were negative, RRP was performed using the standard Walsh procedure.
RESULTS During the follow-up period after RRP, hernias developed in 25 patients, and none developed in UROLOGY 66 (4), 2005
176 patients. The follow-up periods were similar for both groups (35.06 ⫾ 18.23 months for the hernia group and 29.52 ⫾ 20.67 months for the no-hernia group, P ⫽ 0.127). The preoperative predisposing factors selected for comparison between the two groups were diabetes mellitus, hypertension (with or without coronary artery disease), smoking (with or without chronic obstructive pulmonary disease), and previous unilateral hernioplasty (Table I).11 A significantly greater percentage of patients in the hernia group had undergone previous unilateral hernioplasty than those in the no-hernia group (P ⫽ 0.001). The results from the multivariate analysis of the variables using the logistic regression backward stepwise model are shown in Table II. The odds ratio of previous unilateral hernioplasty was 9.30 (95% confidence interval 2.80 to 30.87, P ⫽ 0.003). Thus, patients who had undergone previous hernioplasty were nine times more likely to develop a post-RRP hernia. Table III shows the comparisons between the two groups according to the postoperative factors such as pathologic stage, specimen weight, use of adjuvant radiotherapy, and postoperative woundrelated complications. Once a wound-related complication occurred, the incidence of hernia formation increased (P ⫽ 0.056). This relationship was examined using logistic regression analysis (Table IV). The odds ratio for wound-related morbidity was 4.935 (95% confidence interval 1.2223 to 19.9257; P ⫽ 0.025). 815
TABLE II. Logistic regression analysis for preoperative factors between two groups Variable
Regression Coefficient
SE
Odds Ratio
95% CI of Odds Ratio
P Value
⫺0.035 7.323 0.115 0.804 2.230 1.910
0.047 21.619 0.487 0.472 0.612 3.265
0.966 1514.739 1.122 2.234 9.299 6.755
0.8816–1.0579 0.0000–3.83E ⫹ 21 0.4321–2.9118 0.8865–5.6309 2.8014–30.8703
0.4535 0.7348 0.8134 0.0883 0.0003* 0.5585
Age Diabetes mellitus (⫹) Hypertension with or without CAD (⫹) Smoking with or without COPD (⫹) Previous unilateral hernioplasty (⫹) Constant KEY: SE ⫽ standard error; other abbreviations as in Table I. * P ⬍0.05 (tested by Wald statistic).
TABLE III. Postoperative factors between patients with and without hernia Hernia Yes (n ⴝ 25)
No (n ⴝ 176)
14.76 ⫾ 6.02 12.28–17.24
13.93 ⫾ 6.99 12.89–14.97
52.28 ⫾ 24.06 42.35–62.21
48.43 ⫾ 28.18 44.23–52.62
Clinical Characteristic Hospitalization stay (days) Mean ⫾ SD 95% CI Specimen (g) Mean ⫾ SD 95% CI Wound-related problem Yes No Adjuvant radiotherapy Yes No Stage Organ-confined disease Extracapsular extension Follow-up (mo) Mean ⫾ SD 95% CI
P Value 0.334*
0.233*
0.056† 7 (28.0) 18 (72.0)
21 (11.9) 155 (88.1)
1 (4.0) 24 (96.0)
20 (11.4) 156 (88.6)
0.482†
0.767‡ 6 (24.0) 19 (76.0)
51 (29.1) 124 (70.9) 0.127*
35.06 ⫾ 18.23 27.54–42.58
29.52 ⫾ 20.67 26.45–32.60
Abbreviations as in Table I. Data presented as number of patients, with percentages in parentheses, unless otherwise noted. * Mann-Whitney U test. † Fisher’s exact test. ‡ Yates correction of contigency.
TABLE IV. Logistic regression analysis for postoperative factors between two groups Variable Hospitalization stay (days) Specimen (g) Wound-related problem (⫹) Adjuvant radiotherapy (⫹) Stage (ECE) Constant
Regression Coefficient
SE
Odds Ratio
95% CI of Odds Ratio
P Value
0.046 ⫺0.007 1.596 1.542 0.751 0.810
0.051 0.007 0.712 1.086 0.545 1.239
1.047 0.993 4.935 4.676 2.119 2.248
0.9477–1.1571 0.9786–1.0072 1.2223–19.9257 0.5561–39.3207 0.7275–6.1693
0.3653 0.3233 0.0250* 0.1556 0.1686 0.5134
KEY: SE ⫽ standard error; CI ⫽ confidence interval; ECE ⫽ extracapsular extension. * P ⬍0.05 (tested by Wald statistic).
COMMENT Although Regan et al.6 introduced the relationship between inguinal hernia formation and RRP in 1996, the etiology of post-RRP inguinal hernia is 816
still poorly understood. The “shutter mechanism,” a U-shaped internal ring that acts as a valve, is believed to be the barrier preventing hernia formation.6 Regan et al.6 stated that, during RRP, a small UROLOGY 66 (4), 2005
defect in the inguinal ring is unwittingly enlarged secondary to the prolonged stretching of the rectus and lower abdominal musculature. We tried to use the pathologic stage and specimen weight as substitutes for the dissection and stretching during RRP to demonstrate that the greater the muscular stretching, the greater the internal ring destruction, and thus the greater the incidence of hernia formation. However, we failed to show any such relationship between pathologic stage and specimen weight and hernia formation (P ⫽ 0.17 for pathologic stage and P ⫽ 0.32 for specimen weight). Lodding et al.9 confirmed the relationship between RRP and inguinal hernia by comparing the incidence of inguinal hernia formation between post-RRP patients and those who had not undergone RRP. They noted that previous unilateral hernioplasty played an important role in the formation of inguinal hernia after RRP. We studied 15 patients with a history of unilateral hernioplasty, and almost 50% (7 of 15) developed a contralateral inguinal hernia after undergoing RRP (P ⫽ 0.001, Fisher’s exact test). Therefore, should we strengthen the contralateral groin simultaneously when we perform RRP in patients who have undergone previous unilateral hernioplasty? Regan et al.6 suggested that urologists should consider repairing any inguinal weakness in the inguinal floor or inguinal ring at RRP. Schlegel and Walsh reported repairing any defect in the inguinal floor or ring while awaiting the frozen section analysis results of pelvic lymph node dissection.6 In Japan, Arai et al.3 reported very low morbidity and mortality after RRP. In their research, the surgical mortality was very low (0.16%), similar to the surgical mortality rate (1 of 201) among our patients. The most common complications we encountered were wound-related complications (7.5%) and anastomotic leakage (4.1%). When we compared our hernia group with our no-hernia group for wound-related problems, 28 patients had postRRP wound problems and these patients had a greater rate of inguinal hernia formation than did the group without wound-related problems. The difference between the groups was statistically significant by the regression backward stepwise method (Table IV). These data suggest that we should examine the groin carefully after RRP, especially among those with postoperative woundrelated problems. Prevention of wound-related problems during RRP may be of significant benefit in decreasing the incidence of post-RRP inguinal hernia. Lodding et al.9 also discussed the formation of postoperative anastomosis stricture, which seemed to be associated with an increased incidence of UROLOGY 66 (4), 2005
groin hernia. Among our patients, only three had significant stricture recorded in their medical records, and all need further management. One of these patients later developed an inguinal hernia, but, because of the small sample size, it was not analyzed in our study.
CONCLUSIONS We suggest that routine repair of the contralateral groin for patients who have undergone previous unilateral hernioplasty could be beneficial for preventing inguinal hernia formation after RRP. Preperitoneal repair of the contralateral groin or the Pfannenstiel incision for concurrent surgery can be done while waiting for the frozen section analysis data.12,13 A prospective randomized study will be done in the future to compare repair with nonrepair of contralateral groin for prevention of contralateral hernia after RRP. Definitely, in patients who developed postoperative wound-related problems, the incidence of postprostatectomy inguinal hernia increased. Prevention of wound-related problems during RRP appeared to decrease postoperative inguinal hernia formation.
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