this condition can cause subfertility or infertility , and psychological trauma in men ( 1 , 2 ) . to prevent ischemic necrosis , treatment should be done as soon as possible . if the testicle can be detorsed within 6 hr , over 90% of patients experience testicular salvage , while success decreases to < 10% after 24 hr ( 3 ) . patients or their parents hesitate to consult doctors for a genital condition because of lack of medical knowledge . distance from home to a medical center and the economic status of the patients ' family may affect the delaying treatment ( 4 ) . etiology of testicular torsion is known as ' bell clapper ' anatomical deformity ( 5 ) . a family history of testicular torsion has been described as one of the etiology ( 6 ) . nationwide studies in the united states and taiwan reported incidences of testicular torsion in males aged 1 - 25 yr as 4.5 cases per 100,000 men per year overall , and 3.5 cases per 100,000 men per year in men < 25 yr of age ( 8 , 9 ) . however , information on koreans is lacking . we performed a nationwide epidemiological study on the epidemiology of testicular torsion in korean men . the korean urologic association operated the uropds ( urologic partitioned data set ) patient registry from 2006 to 2011 . uropds data consists of age , diagnosis , kind of surgery , time of admission and time of discharge . to calculate the incidence rate of testicular torsion in the general population , the total population was cited from the korean statistical information service . a national census was made in 2010 ; and the estimated population was determined every year from 2006 to 2011 . the average incidence of 6 yr was calculated by dividing the total population of males for the 6 yr by the total number of patients . testicular salvage rate was calculated in patients who had undergone orchiopexy divided by the total number of patients . age group was divided as infancy ( < 1 yr ) , children ( 1 - 11 yr ) , adolescents ( 12 - 20 yr ) , and adults ( < 20 yr ) ( 10 ) . pearson chi - square test was used to evaluate the association between variables and testicular salvage . this study was approved by the institutional review board of the samsung medical center in seoul , korea ( irb number , smc 2014 - 05 - 023 ) . pearson chi - square test was used to evaluate the association between variables and testicular salvage . this study was approved by the institutional review board of the samsung medical center in seoul , korea ( irb number , smc 2014 - 05 - 023 ) . from january 2006 to december 2011 , 1,591 cases were included in uropds by a keyword search using ' testicular torsion ' . by year , the number of patients with testicular torsion from 2006 to 2011 was 225 , 254 , 272 , 280 , 346 , and 213 , respectively . the incidence of testicular torsion in male was 1.1 per 100,000 and 2.9 per 100,000 in males < 25 yr old . incidence rate was decreased after the middle age , the disease can occur at any age ( table 2 ) . total testicular salvage rate was 75.7% overall and 75.4% for those < 25 yr of age . testicular salvage rate in infancy was 65.9% , which was lower than any other age group , but not statistically significant . testicular torsion is a well known emergency in urology and can occur at any age . our study shows that the incidence was 2.9 cases per 100,000 person years of males < 25 yr of age and 1.1 cases per 100,000 person years at all ages . the incidence of testicular torsion in males 1 - 25 yr of age has been reported as 4.5 cases per 100,000 male subjects per year in the united states ( 8) . a us study indicated that the estimated yearly incidence of testicular torsion for males < 18 yr of age was 3.8 per 100,000 ( 4 ) . another nationwide study in taiwan reported 3.5 cases per 100,000 person years for males < 25 yr of age ( 9 ) . an incidence of 1.4 cases per 100,000 men was reported in brazil ( 11 ) . it may reflect the clinical distinction between extravaginal torsion in newborns and infants and children ( 12 ) . many nationwide studies have been on the basis of the statistcs of the country and are classified based on international classification of disease ( icd ) . with these methods , there is a possibility of miscoding if symptoms are similar with testicular torsion . for example , miscoding can occur when diagnosis changes after scrotal exploration . in the case of the uropds data , a doctor needed to enter the data directly after final diagnosis . most testicular torsion patients visit a hospital presenting with scrotal pain , swelling , and erythema ( 13 ) . as a general rule , the decision depends on testicular color when a physician detorses the testis in the surgical field . a continuous black color , which means irreversible necrosis , is the most indicative of the need for testicle removal . delayed diagnosis and treatment can increase the rate of testicular removal . in this study , cost et al . ( 14 ) reported a 68.1% salvage rate from patients aged 1 - 17 yr old and zhao et al . ( 15 ) studied testicular salvage rate by ages of 17 - 20 and 21 - 34 yr . the salvage rate differed with 70.3% , of testes salvaged in the younger group versus only 41% in the older group . in taiwan , huang et al . ( 9 ) reported a rate of 74.4% in patients < 25 yr of age . testicular salvage in torsion depends on timely presentation , diagnosis , and surgical intervention . in other time sensitive disease , such as appendicitis and myocardial infarction , efforts to improve outcomes have traditionally focused on public awareness to expedite presentation and provider education to hasten diagnosis ( 16 , 17 ) . notably , there is similar testis salvage rate between rural and urban area in korea . in the us , ( 4 ) reported that age , insurance type , and living area influence testicular salvage rate . this better salvage rate in korea is presumed to be due to the result of small size of territory , dense distribution of hospitals , and national health insurance of korea ( nhi ) . the nhi system initially offered plans with low premiums , low benefits , and low doctors ' fees to contribute to eliminating inequities based on socioeconomic status . this approach improved access to medical services , eliminated gaps between urban and rural areas and between different classes with respect to the use of services ( 18 ) . in the future , korean urologists will likely decline due to decreased urology residents in korea , so similar longitudinal study design will be interesting in the future . this variable is involved to evaluate influence of medical accessibility but it is hard to reflect each patient 's medical accessibility . in conclusion , the incidence of testicular torsion in males aged < 26 yr was 2.9 cases per 100,000 men per year . approximately 75.7% patients with testicular torsion finally received orchiopexy in korea . to minimize the possibility of orchiectomy for testicular torsion , it is important to improve public awareness to expedite presentation and provider education to hasten diagnosis and surgery .
testicular torsion is a surgical emergency in the field of urology . 
 knowledge of the epidemiology and pathophysiology is significant to an urologist . 
 however , the epidemiology of testicular torsion in korea has not been studied . 
 we performed a nationwide epidemiological study to improve knowledge of the epidemiology of testicular torsion . from 2006 - 2011 , 
 the korean urologic association began the patient registry service . 
 the annual number of patients with testicular torsion from 2006 to 2011 were 225 , 250 , 271 , 277 , 345 , and 210 , respectively . 
 the overall incidence of testicular torsion in males was 1.1 per 100,000 ; however , the incidence in men less than 25 yr old was 2.9 per 100,000 . 
 adolescents showed the highest incidence . 
 total testicular salvage rate was 75.7% in this survey . 
 there was no geographic difference of testicular salvage rate . 
 minimizing the possibility of orchiectomy for testicular torsion is important to improve public awareness to expedite presentation and provider education to improve diagnosis and surgery.graphical abstract