title: Role of Sonography in Clinically Occult Femoral Hernias.
abstract: OBJECTIVE
  The purpose of this article is to evaluate the diagnostic accuracy of sonography in clinically occult femoral hernias and to describe our sonographic technique.
  
  
  METHODS
  The clinical and imaging data for 93 outpatients referred by general surgeons, all of whom underwent sonographic evaluation and surgery, were reviewed retrospectively. Of these, 55 patients who underwent surgical exploration for groin hernias within 3 months of sonography and met all inclusion criteria were included in the study. The sonographic technique involves using the pubic tubercle as an osseous landmark to identify and appropriately visualize the femoral canal. The Valsalva maneuver is then used to differentiate the movement of normal fat (a potential pitfall) from true herniation in the femoral canal. Surgical findings were used as the reference standard by which sonographic results were judged. Two-by-two contingency tables were used to calculate the sensitivity, specificity, positive predictive value, and negative predictive value.
  
  
  RESULTS
  In these 55 patients, surgery revealed 15 femoral hernias. Eight femoral hernias occurred in women, and 7 occurred in men. For diagnosing femoral hernias, sonography demonstrated sensitivity of 80%, specificity of 88%, a positive predictive value of 71%, and a negative predictive value of 92%. True-positive cases of femoral hernias have a sonographic appearance of a hypoechoic sac with speckled internal echoes. When examining during the Valsalva maneuver, a femoral hernia passes deep to the inguinal ligament, expands the femoral canal, displacing the normal canal fat, and effaces the femoral vein.
  
  
  CONCLUSIONS
  Sonography can exclude femoral hernias with high confidence in light of its exceptional negative predictive value. With attention to technique and imaging criteria, the diagnostic accuracy of sonography can be enhanced.
authors.affiliation: From the University of Michigan Health System, Ann Arbor, Michigan USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Brandel
authors.affiliation: From the University of Michigan Health System, Ann Arbor, Michigan USA. ggirish@med.umich.edu.
authors.forename: Gandikota
authors.initials: G
authors.lastname: Girish
authors.affiliation: From the University of Michigan Health System, Ann Arbor, Michigan USA.
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Brandon
authors.affiliation: From the University of Michigan Health System, Ann Arbor, Michigan USA.
authors.forename: Qian
authors.initials: Q
authors.lastname: Dong
authors.affiliation: From the University of Michigan Health System, Ann Arbor, Michigan USA.
authors.forename: Corrie
authors.initials: C
authors.lastname: Yablon
authors.affiliation: From the University of Michigan Health System, Ann Arbor, Michigan USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Jamadar
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006550:Hernia, Femoral / Q000000981:diagnostic imaging*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D056888:Patient Positioning / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods*; D014636:Valsalva Maneuver
keywords: femoral canal; femoral hernia; hernia diagnosis; hernia evaluation; occult hernia; superficial structures