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US Findings in the Scrotum of Extreme Mountain Bikers¹

¹ From the Departments of Radiology II (F.F., A.K., G.H., B.A., D.z.N.) and Urology (A.S.), University Hospital Innsbruck, Austria. From the 1999 RSNA scientific assembly. Received June 21, 2000; revision requested July 28; revision received September 5; accepted October 2. Address correspondence to F.F., Department of Radiology, Division of Diagnostic Ultrasound, Thomas Jefferson University, 132 S 10th St, Main Bldg, Seventh Fl, Philadelphia, PA 19107-5244 (e-mail: ferdinand.frauscher@uibk.ac.at).

	ABSTRACT

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PURPOSE: To sonographically investigate whether mountain bikers have a higher prevalence of scrotal abnormalities compared with that in nonbikers.

MATERIALS AND METHODS: Eighty-five male mountain bikers (mean age, 25 years; age range, 17–45 years) and 31 healthy nonbikers (mean age, 24 years; age range, 15–37 years) were examined for scrotal findings at ultrasonography (US). Only male subjects with a history of extensive off-road biking (2 h/d 6 d/wk; covered distance, >5,000 km/y) were assigned to the group of mountain bikers, whereas the control group did not engage in bicycling. In addition to clinical evaluation, US examination of the scrotum was performed by using a linear-array transducer operating at a frequency of 8.0 MHz.

RESULTS: Eighty (94%) mountain bikers had abnormal findings at scrotal US. Thirty-nine (46%) had a history of intermittent scrotal tenderness or discomfort but no severe scrotal trauma. Abnormal findings at US included scrotal calculi in 69 (81%), epididymal cysts in 39 (46%), epididymal calcifications in 34 (40%), testicular calcifications in 27 (32%), hydroceles in 24 (28%), varicoceles in nine (11%), and testicular microlithiasis in one (1%). In the control group, abnormal findings were noted in five (16%), all of whom had epididymal cysts. The overall difference in the number of scrotal abnormalities in bikers compared with the number in nonbikers was significant (P < .0001, ² test).

CONCLUSION: US shows a significantly higher prevalence of extratesticular and testicular disorders in these mountain bikers compared with nonbikers.

Index terms: Athletic injuries, 847.43 • Epididymis, 847.311, 847.81 • Scrotum, abnormalities, 847.43 • Scrotum, calculi, 847.81 • Scrotum, US, 847.1298, 847.12983, 847.12989 • Testis, calculi, 847.81

	INTRODUCTION

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Since their introduction in the late 1970s, off-road bicycles—commonly known as mountain bikes—have become increasingly popular worldwide (1). There are currently an estimated 10 million mountain bikers in the United States. As the popularity of off-road cycling has increased, so have the interest in and level of participation in the competitive aspects of the sport (2).

Bicycle injuries are an important cause of morbidity and mortality in the United States and account for about 500,000 visits per year to emergency departments, with estimated annual economic costs of more than $1 billion (3). Cyclists are in contact with their bicycles at the pedals, seats, and handlebars, each being associated with particular injuries (4,5). Comparisons between on- and off-road cycling events indicate that more off-road cyclists sustain fractures, dislocations, and concussions than their on-road counterparts (6). It is, above all, off-road biking that causes repeated, chronic microtrauma of the perineum secondary to shocks and vibration of the saddle from the rough terrain (2).

Perineal trauma, such as chafing, perineal folliculitis and furuncles, subcutaneous perineal nodules, and traumatic urethritis, are related to the bikers’ contact with the saddle (7,8). Problems of this kind can be minimized by adjusting the seat height, angle, and fore and aft positions, in addition to using a different saddle (1). Furthermore, male impotence, probably developing as a complication of pudendal neuropathy, has been documented (9–13) as an occasional problem. Use of padding in both saddles and shorts may prevent these problems.

So far, no association between biking and alterations of the scrotal contents has been reported, to our knowledge. Yet, microtrauma may cause pathologic changes in the scrotum.

Ultrasonography (US) is the method of choice for imaging the scrotal contents (14). This imaging modality allows for accurate differentiation between the testicular and the extratesticular space and excellent depiction of the testis, the epididymis, and the intrascrotal portion of the spermatic cord (15). At US, scrotal abnormalities have been found (16,17) in 29% of healthy individuals and in 40% of infertile men. The majority of these abnormalities were epididymal and testicular cysts. Calcifications were found (16) in 3% of healthy individuals.

In the present study, scrotal US with a high-frequency transducer was used to investigate whether mountain bikers have a higher prevalence of scrotal abnormalities compared with nonbikers.

	MATERIALS AND METHODS

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Study Population
Between March and December 1999, 85 male amateur mountain bikers aged 17–45 years (mean age, 25 years ± 9.8 [SD]) volunteered to enter this study. All of them reported a minimum of 2 h/d 6 d/wk of off-road biking. Furthermore, they had all covered a distance of more than 5,000 km with their mountain bikes annually. Their biking experience varied from 7 to 26 years (mean, 11 years ± 5.6). An additional 31 healthy nonbiking volunteers aged 15–37 years of age (mean age, 24 years ± 8.3) were included as control subjects. The comparison between the age of the mountain bikers and that of the control subjects revealed no statistically significant difference (P > .05, Student t test). Approval for this study was obtained from the institutional review board, and written informed consent was obtained from both the bikers and the nonbikers.

At the Department of Urology, all bikers and nonbikers underwent clinical assessment, including evaluation of a history of pain, discomfort, and scrotal trauma or inflammation, as well as scrotal inspection and palpation for swelling, induration, tenderness, or other abnormalities (ie, a palpable mass or irregularity on the surface of the scrotal contents).

US Examination
US was performed together and findings were interpreted in consensus by two radiologists (F.F., A.K.) with extensive experience in genitourinary US.

For the investigations, a US unit (Sequoia 512; Acuson, Mountain View, Calif) equipped with a high-frequency (8.0-MHz) linear-array transducer was used. All bikers and nonbikers underwent a standard US examination of the scrotum. Gray-scale US images of the testicles were obtained in the transverse and longitudinal planes by using an anterior approach to measure the size of the testicles. In the epididymis, we measured the greatest length and the anteroposterior diameter on longitudinal scans and measured the width on transverse scans of the head of the epididymis. Furthermore, US was performed to identify abnormalities of the scrotal contents, such as epididymal cysts, hydroceles, scrotal calculi, testicular calcifications, epididymal calcifications, and testicular microlithiasis. Testicular microlithiasis was defined as the presence of more than five microliths per transducer field (18).

Color Doppler US was performed to identify varicoceles, which were diagnosed on the basis of a venous diameter of 3 mm or larger, with the diameter increasing during the Valsalva maneuver or during a change from the supine to the upright position. Increased venous retrograde flow in the pampiniform plexus when the subject was in the upright position or when the Valsalva maneuver was performed was used as supporting evidence of varicocele (19). The US findings were documented on videotapes and printouts.

Follow-up information was obtained if the findings at US resulted in further evaluation or therapy.

To compare the overall frequency of US abnormalities in bikers versus nonbikers, a 2 x 2 table was constructed to demonstrate the number of abnormalities in each group. A ² statistic (Epi-Info software; Centers for Disease Control, Atlanta, Ga) was computed to determine whether there was a significant difference in the frequency of abnormalities between the two groups. We compared the difference in the size of the testicles and epididymides between the two groups by using a Student t test. In addition, we compared the prevalence of epididymal cysts in the two groups and the overall frequency of US findings with the presence of clinical symptoms in mountain bikers by using the Fisher exact test. A P value of less than .05 was considered to indicate a statistically significant difference.

To compare the presence of specific US findings with clinical symptoms in mountain bikers, multiple comparisons were performed for each US finding. The P value was adjusted for 16 multiple comparisons by using the Bonferroni method with an adjusted cutoff for the P value of .003 (20).

	RESULTS

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Mountain Bikers
Eighty (94%) of 85 bikers had pathologic abnormalities of the scrotal contents. We found 127 scrotal calculi (Fig 1), with a mean size of 0.4 cm ± 0.3 (range, 0.2–1.4 cm) in 69 (81%) bikers; 52 epididymal cysts (Fig 2), with a mean size of 0.9 cm ± 0.7 (range, 0.3–3.1 cm) in 39 (46%) bikers; 71 epididymal calcifications (Fig 3), with a mean size of 0.2 cm ± 0.1 (range, 0.1–0.4 cm) in 34 (40%) bikers; 50 testicular calcifications (Fig 4), with a mean size of 0.3 cm ± 0.2 (range, 0.1–0.7 cm) in 27 (32%) bikers; 36 small and nine moderate hydroceles in 24 (28%) bikers; left-sided varicoceles in nine (11%) bikers; and testicular microlithiasis (both sided) (Fig 5) in one (1%) biker. Table 1 shows a comparison of the US findings obtained in mountain bikers and nonbikers.

View larger version (132K): [in this window] [in a new window] [Download PPT slide]   Figure 1. Longitudinal ultrasonogram shows a free-floating calculus (between crosshairs) in the area of the lower part of the right scrotum, localized to the tail of the epididymis in a 28-year-old mountain biker.

View larger version (129K): [in this window] [in a new window] [Download PPT slide]   Figure 2. Longitudinal ultrasonogram demonstrates an epididymal cyst (between crosshairs) in the area of the head of the right epididymis in a 33-year-old mountain biker.

View larger version (137K): [in this window] [in a new window] [Download PPT slide]   Figure 3. Longitudinal ultrasonogram demonstrates an epididymal calcification (arrow) in the area of the head of the left epididymis in a 29-year-old mountain biker.

View larger version (132K): [in this window] [in a new window] [Download PPT slide]   Figure 4. Longitudinal ultrasonogram shows calcifications (arrows) in the right testicle in a 34-year-old mountain biker.

View larger version (112K): [in this window] [in a new window] [Download PPT slide]   Figure 5. Longitudinal ultrasonogram demonstrates echogenic foci of testicular microlithiasis (more than five microliths in one transducer field) of the right testicle in a 29-year-old mountain biker.

At physical examination, 39 (46%) bikers had scrotal tenderness, discomfort, or abnormal findings with palpation (ie, palpable mass or irregularity on the surface of the scrotal contents), but they gave no history of severe scrotal trauma or inflammation. All of these 39 symptomatic bikers had pathologic findings at US examination. Among mountain bikers, there was a marginally significant association between symptoms and overall frequency of US findings (P = .059, Fisher exact two-tailed test) (Table 2). However, 51% (41 of 80 bikers) of positive US findings were seen in the asymptomatic group. Table 3 presents the comparison on the basis of the presence or absence of symptoms for each US finding.

Nonbikers
At US, five (16%) of 31 nonbikers showed pathologic changes in the scrotum. In all five cases, epididymal cysts, with a mean size of 0.5 cm ± 0.3 (range, 0.2–1.3 cm), were depicted. The prevalence of epididymal cysts was significantly lower in nonbikers compared with that of mountain bikers (P = .002, Fisher exact test). Among nonbikers, none were symptomatic at clinical examination. Furthermore, they also reported no history of severe scrotal trauma or inflammation.

Measurements of testicles were obtained in 29 (94%) of 31 subjects. The mean size of the testicles was 3.9 x 3.0 x 2.9 cm (range, 3.4 x 2.8 x 2.7 to 4.0 x 3.4 x 3.0 cm). Evaluation of the head of the epididymides was indeterminate in two (6%) of 31 nonbikers, due to epididymal cysts. The mean size in the remaining 29 control subjects was 0.9 x 1.0 x 0.7 cm (range, 0.6 x 1.0 x 0.5 to 1.3 x 1.5 x 1.2 cm). Comparison of testicle and epididymis head volume between bikers and nonbikers demonstrated no statistically significant difference (P > .05).

Results of a ² test are presented in Table 4, which demonstrates a significantly higher prevalence of testicular and extratesticular disorders in the mountain bikers than in the nonbikers (² = 70.6; P < .0001).

	DISCUSSION

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The most common US findings were benign nonneoplastic scrotal masses, so-called scrotal calculi, which were seen in 81% of cases. Scrotal calculi may result from torsion of the appendix testis or the epididymis, from hematomas, or from inflammation of the tunica vaginalis testis (21). These benign calcifications may appear as painful (ie, after repeated palpation by the patient) free-floating or dependent scrotal masses (15). However, 39 of 69 bikers who had scrotal calculi were asymptomatic. Scrotal calculi may be detected with palpation by the bikers themselves and may raise concerns about testicular tumor, as the prevalence of this malignancy in the age group between 20 and 35 years is high (22). Furthermore, calcifications of the epididymis and testis were seen, respectively, in 40% and 32% of only bikers. Gerscovich (23) reported that scrotal calcifications may result from trauma. We also believe that these calcifications are related to previous trauma, inflammation, and/or degeneration.

Testicular microlithiasis has been reported (24) to be associated with testicular tumor in some cases. We found testicular microlithiasis in one (1%) biker, but testicular biopsy revealed no evidence of tumor. The reported (25) prevalence of testicular microlithiasis is approximately 2%. Hence, in this sample, mountain biking does not seem to increase the risk of development of testicular microlithiasis.

The high prevalence of extratesticular and testicular calcifications caused us to believe that these pathologic changes of the scrotal contents resulted primarily from chronic, repeated microtrauma. Vuong et al (7) reported perineal nodular indurations—also referred to as accessory testicles—in cyclists to result from microtrauma (ie, subclinical traumatization) to the perineum secondary to saddle vibration.

Our findings also included epididymal cysts, which were found in 46% of bikers and 16% of nonbikers. These scrotal abnormalities were symptomatic in 26 (31%) of 85 bikers, whereas in the control group, all epididymal cysts were asymptomatic. A higher prevalence (29%) was reported (16) in asymptomatic men than in our nonbikers. It may be speculated that the significantly higher rate (P < .001) of epididymal cysts in mountain bikers is also attributable to repeated microtrauma of the epididymis.

Hydroceles were observed in 28% of mountain bikers and varicoceles in 11%. Up to 50% of acquired hydroceles are the result of trauma (14). Only three of the nine bikers who had varicoceles at US had positive findings with palpation, which is the routine screening test for varicocele, the most common abnormality in infertile men. According to Pierik et al (26), nonpalpable scrotal abnormalities are frequently detected at scrotal US in infertile men. They concluded that the relatively high prevalence of testicular abnormalities emphasizes the importance of routine scrotal US.

Bilateral pudendal nerve injury secondary to excessive biking has been reported (9) to be a saddle-related condition, and if the blood supply to the penis is compromised, male erectile dysfunction may develop. We assume that the abnormalities of the scrotal contents that we detected are basically also a saddle-related problem. The mechanical component responsible for these scrotal changes may be reduced by improving the padding of the seat or shorts, adjusting the saddle angle to either horizontal or downward in front, adjusting the saddle height, using an ergonomically designed saddle, or taking frequent pauses during each ride. Furthermore, new shock-absorbent saddles and full-suspension bikes may help reduce saddle vibration and, thus, the amount of microtrauma.

The majority of our mountain bikers used the recommended saddle adjustment, and they wore padded shorts. However, none of our bikers used full-suspension bikes (they used only front-suspension systems) or padded seats, because these new seats have been available in Austria for only a few months. Therefore, future studies on mountain bikers who use these protective measures are necessary to evaluate the clinical outcome.

In summary, we found a significantly higher prevalence of abnormalities of the scrotal contents in mountain bikers compared with nonbikers (P < .0001). The most common findings were scrotal calcifications, which were seen in up to 81% of cases. However, only 46% of bikers presented with clinical symptoms. Such saddle-related problems may result from a high rate of microtrauma to the scrotal contents, and US allows for excellent detection of these scrotal abnormalities.

	ACKNOWLEDGMENTS

 
The authors thank Ethan J. Halpern, MD, for his assistance with the preparation of the manuscript.

	FOOTNOTES

 
Author contributions: Guarantors of integrity of entire study, F.F., A.K., D.z.N., G.H.; study concepts and design, F.F.; literature research, G.H.; clinical studies, F.F., A.K., A.S.; data acquisition, A.K.; data analysis/interpretation, B.A.; statistical analysis, A.K.; manuscript preparation, F.F.; manuscript definition of intellectual content, A.K.; manuscript editing, D.z.N.; manuscript revision/review, F.F., A.S.; manuscript final version approval, A.K., D.z.N., G.H.

	REFERENCES

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 

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