title: Interobserver variability of sonography for prediction of placenta accreta.
abstract: OBJECTIVE
  The sensitivity of sonography to predict accreta has been reported as higher than 90%. However, most studies are from single expert investigators. Our objective was to analyze interobserver variability of sonography for prediction of placenta accreta.
  
  
  METHODS
  Patients with previa with and without accreta were ascertained, and images with placental views were collected, deidentified, and placed in random sequence. Three radiologists and 3 maternal-fetal medicine specialists interpreted each study for the presence of accreta and specific findings reported to be associated with its diagnosis. Investigator-specific sensitivity, specificity, and accuracy were calculated. κ statistics were used to assess variability between individuals and types of investigators.
  
  
  RESULTS
  A total of 229 sonographic studies from 55 patients with accreta and 56 control patients were examined. Accuracy ranged from 55.9% to 76.4%. Of imaging studies yielding diagnoses, sensitivity ranged from 53.4% to 74.4%, and specificity ranged from 70.8% to 94.8%. Overall interobserver agreement was moderate (mean κ ± SD = 0.47 ± 0.12). κ values between pairs of investigators ranged from 0.32 (fair agreement) to 0.73 (substantial agreement). Average individual agreement ranged from fair (κ = 0.35) to moderate (κ = 0.53).
  
  
  CONCLUSIONS
  Blinded from clinical data, sonography has significant interobserver variability for the diagnosis of placenta accreta.
authors.affiliation: Department of Obstetrics and Gynecology, University of Utah Health Sciences Center and Intermountain Healthcare (Z.S.B., A.G.E., D.S.R., R.M.S.), and Department of Radiology, University of Utah Health Sciences Center (A.M.K., T.C.W., P.J.W.), Salt Lake City, Utah USA. zachary.bowman@hsc.utah.edu.
authors.forename: Zachary S
authors.initials: ZS
authors.lastname: Bowman
authors.affiliation: Department of Obstetrics and Gynecology, University of Utah Health Sciences Center and Intermountain Healthcare (Z.S.B., A.G.E., D.S.R., R.M.S.), and Department of Radiology, University of Utah Health Sciences Center (A.M.K., T.C.W., P.J.W.), Salt Lake City, Utah USA.
authors.forename: Alexandra G
authors.initials: AG
authors.lastname: Eller
authors.affiliation: Department of Obstetrics and Gynecology, University of Utah Health Sciences Center and Intermountain Healthcare (Z.S.B., A.G.E., D.S.R., R.M.S.), and Department of Radiology, University of Utah Health Sciences Center (A.M.K., T.C.W., P.J.W.), Salt Lake City, Utah USA.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Kennedy
authors.affiliation: Department of Obstetrics and Gynecology, University of Utah Health Sciences Center and Intermountain Healthcare (Z.S.B., A.G.E., D.S.R., R.M.S.), and Department of Radiology, University of Utah Health Sciences Center (A.M.K., T.C.W., P.J.W.), Salt Lake City, Utah USA.
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Richards
authors.affiliation: Department of Obstetrics and Gynecology, University of Utah Health Sciences Center and Intermountain Healthcare (Z.S.B., A.G.E., D.S.R., R.M.S.), and Department of Radiology, University of Utah Health Sciences Center (A.M.K., T.C.W., P.J.W.), Salt Lake City, Utah USA.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Winter
authors.affiliation: Department of Obstetrics and Gynecology, University of Utah Health Sciences Center and Intermountain Healthcare (Z.S.B., A.G.E., D.S.R., R.M.S.), and Department of Radiology, University of Utah Health Sciences Center (A.M.K., T.C.W., P.J.W.), Salt Lake City, Utah USA.
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Woodward
authors.affiliation: Department of Obstetrics and Gynecology, University of Utah Health Sciences Center and Intermountain Healthcare (Z.S.B., A.G.E., D.S.R., R.M.S.), and Department of Radiology, University of Utah Health Sciences Center (A.M.K., T.C.W., P.J.W.), Salt Lake City, Utah USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Silver
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D015588:Observer Variation; D010921:Placenta Accreta; D011247:Pregnancy; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000379:methods*
keywords: interobserver variability; obstetric ultrasound; placenta accreta; prenatal diagnosis; sensitivity and specificity; sonography