title: The true incidence of cryptorchidism in Denmark.
abstract: OBJECTIVE
  Considerable controversy exists regarding the recently published high prevalence of cryptorchidism and the actual orchiopexy rate in Denmark. Therefore, we carried out another prevalence study.
  
  
  METHODS
  The study population included 1,094 consecutive males delivered alive at Glostrup University Hospital during 2002, with a 4-year review of patient data and telephone contact with primary physicians.
  
  
  RESULTS
  At birth the overall frequency of cryptorchidism was 2.4% (26 of 1,088 cases, 23% bilateral). The frequency of cryptorchidism in singletons was 2.4% (24 of 1,012 patients). The frequency of cryptorchidism in patients with a birth weight of 2,500 gm or more was 2.1%, compared to 8.2% in those with a birth weight of less than 2,500 gm (chi-square p <0.05). The frequency of cryptorchidism in twins was 2.6% (2 of 76). The frequency of birth weight below 2,500 gm was 51% (39 of 76) in twins and 4.9% (50 of 1,012) in singletons (chi-square p <0.00005). The weight of the placenta was higher in twins (median 1,000 gm) than in singletons (650 gm). At age 4 years 1.6% of the boys had undergone or were waiting to undergo surgery for cryptorchidism, and 0.6% had a diagnosis of retractile testes.
  
  
  CONCLUSIONS
  In a small cohort of newborns the incidence of cryptorchidism in Denmark has not changed, and is similar to previous reports from the 1950s. The risk is higher in low birth weight singleton neonates but does not appear to be higher in twins, despite lower birth weight and prematurity.
authors.affiliation: Department of Pediatrics, Glostrup Hospital, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Dina
authors.initials: D
authors.lastname: Cortes
authors.forename: Emma M
authors.initials: EM
authors.lastname: Kjellberg
authors.forename: Mette
authors.initials: M
authors.lastname: Breddam
authors.forename: Jorgen
authors.initials: J
authors.lastname: Thorup
mesh_terms: D003456:Cryptorchidism / Q000453:epidemiology*; D003718:Denmark / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D008297:Male; D012189:Retrospective Studies