title: Sonography of acute right lower quadrant pain: importance of increased intraabdominal fat echo.
abstract: OBJECTIVE
  The purpose of our study was to assess the diagnostic usefulness of increased intraabdominal fat echo during the sonographic evaluation of patients with acute right lower quadrant (RLQ) pain.
  
  
  METHODS
  A total of 328 consecutive patients (132 male and 196 female; mean age, 28+/-15 [SD] years) with acute RLQ pain prospectively underwent transabdominal sonography by one of three experienced radiologists. The radiologists prospectively graded intraabdominal fat echo using a 3-point scale: 1, normal; 2, slight increase; and 3, marked and diffuse increase. Final diagnoses were made using surgical or pathologic findings or by clinical follow-up. Of the 328 patients, 11 were lost to follow-up and excluded from analysis. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of increased intraabdominal fat echo were calculated for a positive final diagnosis.
  
  
  RESULTS
  Final diagnoses were negative (n=103), acute appendicitis (n=137), right colonic diverticulitis (n=18), mesenteric lymphadenitis (n=13), enteritis (n=26), and others (n=20). Grades of intraabdominal fat echo were grade 1 (n=158), grade 2 (n=35), and grade 3 (n=124). Overall, fat echo grades 2 or 3 were more frequently observed in patients with a positive final diagnosis (73% [157/214] vs 2% [2/103], p<0.001) than in those with a negative final diagnosis. Sensitivity, specificity, accuracy, PPV, and NPV of increased intraabdominal fat echo for a positive final diagnosis were 73%, 98%, 81%, 99%, and 64%. Increased intraabdominal fat echo was documented in 89% (122/137) of cases of acute appendicitis and in 100% (18/18) of cases of right colonic diverticulitis.
  
  
  CONCLUSIONS
  An increased intraabdominal fat echo on sonography is highly specific for the presence of RLQ inflammatory disease.
authors.affiliation: Department of Radiology, Konkuk University Hospital and Konkuk University School of Medicine, Hwayang-dong, Gwangjin-gu, Seoul, 143-729, Korea.
authors.forename: Min Woo
authors.initials: MW
authors.lastname: Lee
authors.forename: Young Jun
authors.initials: YJ
authors.lastname: Kim
authors.forename: Hae Jeong
authors.initials: HJ
authors.lastname: Jeon
authors.forename: Sang Woo
authors.initials: SW
authors.lastname: Park
authors.forename: Sung Il
authors.initials: SI
authors.lastname: Jung
authors.forename: Jeong Geun
authors.initials: JG
authors.lastname: Yi
mesh_terms: D050153:Abdominal Fat / Q000000981:diagnostic imaging*; D015746:Abdominal Pain / Q000175:diagnosis* / Q000209:etiology*; D000328:Adult; D001064:Appendicitis / Q000150:complications* / Q000175:diagnosis*; D043963:Diverticulosis, Colonic / Q000150:complications* / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods*