title: Late-presenting posterior transdiaphragmatic (Bochdalek) hernia in adults: prevalence and MDCT characteristics.
abstract: OBJECTIVE
  The objective of our study was to determine the prevalence of posterior transdiaphragmatic hernia in a large normal adult population. We also performed volume measurements and described its characteristics and sequential changes.
  
  
  METHODS
  We prospectively evaluated 3107 chest computed tomography screenings obtained at our center between September 2005 and March 2006. The images were analyzed by experienced radiologists, who focused on the distribution, size, content, and sequential changes of the diaphragmatic hernia. Volumetric measurement was used to evaluate the size of the hernia. We also performed a chart review for each case and recorded the sex, age, symptoms, and clinical history.
  
  
  RESULTS
  A total of 525 hernias were identified in 396 of 3107 persons, representing an incidence of 12.7%. Age ranges were 36 to 86 years and average was 62.8 years. The prevalence of the posterior diaphragmatic hernias in the 50s, 60s, and 70s age groups was 10.5% (168/1596), 13.7% (137/1003), and 20.3% (80/394), respectively. All persons were asymptomatic. In 93.7% (492/525) of the hernias, only fat was observed, whereas kidney involvement was observed in 5.5% (29/525). Protruded hernia content extended along the diaphragm, thoracoabdominal wall, and in the intermediate position between these 2 structures in 53.7%, 32.8%, and 13.5% of the hernias, respectively. No significant sequential changes were observed (P=0.082) during our follow-up period (12 to 27 mo).
  
  
  CONCLUSIONS
  Incidentally observed posterior transdiaphragmatic hernias are a common finding on multidetector-row computed tomography, occurring in up to 20% of persons by age 70 years.
authors.affiliation: Department of Radiology, St. Luke's International Hospital, Chuo-ku, Tokyo, Japan. tamachan@akita-noken.go.jp
authors.forename: Fumiko
authors.initials: F
authors.lastname: Kinoshita
authors.forename: Mitsutomi
authors.initials: M
authors.lastname: Ishiyama
authors.forename: Satoshi
authors.initials: S
authors.lastname: Honda
authors.forename: Masaki
authors.initials: M
authors.lastname: Matsuzako
authors.forename: Katsunori
authors.initials: K
authors.lastname: Oikado
authors.forename: Toshibumi
authors.initials: T
authors.lastname: Kinoshita
authors.forename: Yukihisa
authors.initials: Y
authors.lastname: Saida
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D005260:Female; D006548:Hernia, Diaphragmatic / Q000000981:diagnostic imaging* / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed