title: Distribution of Epididymal Involvement in Mumps Epididymo-orchitis.
abstract: OBJECTIVE
  To evaluate characteristic sonographic findings for mumps orchitis with epididymal involvement.
  
  
  METHODS
  This study included 18 patients (aged 12-18 years) with mumps orchitis. We assessed the volume, echogenicity, and vascularity of the testes and the transverse diameter, echogenicity, and vascularity of the epididymal head, body, and tail. We classified 4 types of epididymal involvement: 1A, focal swelling of the epididymal head with hypervascularity only on the swollen head; 1B, focal swelling of the epididymal head with hypervascularity on the entire epididymis; 1C, diffuse swelling of the entire epididymis with hypervascularity; and 2, no epididymal involvement. The Student t test was used to evaluate the significance of the size of each part of the epididymis and the epididymal head-to-tail diameter ratio.
  
  
  RESULTS
  Orchitis was unilateral in 13 patients and bilateral in 5. Of 23 affected hemiscrotums, 7 (30.4%) were type 1A, 4 (17.4%) type 1B, 2 (8.7%) type 1C, and 10 (43.5%) type 2. In 11 patients with unilateral epididymal involvement, the mean diameters ± SDs of the epididymal heads on the affected and contralateral sides were 1.11 ± 0.19 (range, 0.7-1.7) and 0.65 ± 0.14 (0.3-0.9) cm (significantly different, P <.001). The diameters of the epididymal tails on the affected and contralateral sides were 0.51 ± 0.41 (0.2-0.8) and 0.46 ± 0.21 (0.3-0.6) cm (not statistically different, P = .106). The mean head-to-tail ratios on the affected and contralateral sides were 2.28 ± 0.49 (1.29-3.00) and 1.41 ± 0.22 (1.00-1.75; significantly different, P < .001). In all types 1A and 1B, the ratio was higher than 2.00; in 22 of 23 unaffected epididymides, the ratio was lower than 2.00.
  
  
  CONCLUSIONS
  Focal swelling of epididymal heads was a characteristic sonographic finding of mumps epididymo-orchitis, and a head-to-tail ratio higher than 2.00 can be a useful diagnostic finding.
authors.affiliation: Department of Diagnostic Radiology, Kyung Hee University Hospital, College of Medicine, Kyung Hee University, Seoul, Korea. indawn@hanafos.com.
authors.forename: Seong Jin
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Department of Diagnostic Radiology, Kyung Hee University Hospital, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Hyun Cheol
authors.initials: HC
authors.lastname: Kim
authors.affiliation: Department of Diagnostic Radiology, Kyung Hee University Hospital, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Joo Won
authors.initials: JW
authors.lastname: Lim
authors.affiliation: Department of Diagnostic Radiology, Kyung Hee University Hospital, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Sung Kyoung
authors.initials: SK
authors.lastname: Moon
authors.affiliation: Department of Diagnostic Radiology, Kyung Hee University Hospital, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Sung Eun
authors.initials: SE
authors.lastname: Ahn
mesh_terms: D000293:Adolescent; D002648:Child; D004823:Epididymitis / Q000000981:diagnostic imaging* / Q000209:etiology*; D006801:Humans; D008297:Male; D009107:Mumps / Q000150:complications*; D009920:Orchitis / Q000000981:diagnostic imaging* / Q000209:etiology*; D012189:Retrospective Studies; D014463:Ultrasonography
keywords: acute scrotum; epididymis; genitourinary ultrasound; orchitis; sonography; testis