title: Can 3-dimensional power Doppler indices improve the prenatal diagnosis of a potentially morbidly adherent placenta in patients with placenta previa?
abstract: Traditionally, 2-dimensional ultrasound parameters have been used for the diagnosis of a suspected morbidly adherent placenta previa. More objective techniques have not been well studied yet.
  
  
  
  The objective of the study was to determine the ability of prenatal 3-dimensional power Doppler analysis of flow and vascular indices to predict the morbidly adherent placenta objectively.
  
  
  
  A prospective cohort study was performed in women between 28 and 32 gestational weeks with known placenta previa. Patients underwent a two-dimensional gray-scale ultrasound that determined management decisions. 3-Dimensional power Doppler volumes were obtained during the same examination and vascular, flow, and vascular flow indices were calculated after manual tracing of the viewed placenta in the sweep; data were blinded to obstetricians. Morbidly adherent placenta was confirmed by histology. Severe morbidly adherent placenta was defined as increta/percreta on histology, blood loss >2000 mL, and >2 units of PRBC transfused. Sensitivities, specificities, predictive values, and likelihood ratios were calculated. Student t and χ2tests, logistic regression, receiver-operating characteristic curves, and intra- and interrater agreements using Kappa statistics were performed.
  
  
  
  The following results were found: (1) 50 women were studied: 23 had morbidly adherent placenta, of which 12 (52.2%) were severe morbidly adherent placenta; (2) 2-dimensional parameters diagnosed morbidly adherent placenta with a sensitivity of 82.6% (95% confidence interval, 60.4-94.2), a specificity of 88.9% (95% confidence interval, 69.7-97.1), a positive predictive value of 86.3% (95% confidence interval, 64.0-96.4), a negative predictive value of 85.7% (95% confidence interval, 66.4-95.3), a positive likelihood ratio of 7.4 (95% confidence interval, 2.5-21.9), and a negative likelihood ratio of 0.2 (95% confidence interval, 0.08-0.48); (3) mean values of the vascular index (32.8 ± 7.4) and the vascular flow index (14.2 ± 3.8) were higher in morbidly adherent placenta (P < .001); (4) area under the receiver-operating characteristic curve for the vascular and vascular flow indices were 0.99 and 0.97, respectively; (5) the vascular index ≥21 predicted morbidly adherent placenta with a sensitivity and a specificity of 95% (95% confidence interval, 88.2-96.9) and 91%, respectively (95% confidence interval, 87.5-92.4), 92% positive predictive value (95% confidence interval, 85.5-94.3), 90% negative predictive value (95% confidence interval, 79.9-95.3), positive likelihood ratio of 10.55 (95% confidence interval, 7.06-12.75), and negative likelihood ratio of 0.05 (95% confidence interval, 0.03-0.13); and (6) for the severe morbidly adherent placenta, 2-dimensional ultrasound had a sensitivity of 33.3% (95% confidence interval, 11.3-64.6), a specificity of 81.8% (95% confidence interval, 47.8-96.8), a positive predictive value of 66.7% (95% confidence interval, 24.1-94.1), a negative predictive value of 52.9% (95% confidence interval, 28.5-76.1), a positive likelihood ratio of 1.83 (95% confidence interval, 0.41-8.11), and a negative likelihood ratio of 0.81 (95% confidence interval, 0.52-1.26). A vascular index ≥31 predicted the diagnosis of a severe morbidly adherent placenta with a 100% sensitivity (95% confidence interval, 72-100), a 90% specificity (95% confidence interval, 81.7-93.8), an 88% positive predictive value (95% confidence interval, 55.0-91.3), a 100% negative predictive value (95% confidence interval, 90.9-100), a positive likelihood ratio of 10.0 (95% confidence interval, 3.93-16.13), and a negative likelihood ratio of 0 (95% confidence interval, 0-0.34). Intrarater and interrater agreements were 94% (P < .001) and 93% (P < .001), respectively.
  
  
  
  The vascular index accurately predicts the morbidly adherent placenta in patients with placenta previa. In addition, 3-dimensional power Doppler vascular and vascular flow indices were more predictive of severe cases of morbidly adherent placenta compared with 2-dimensional ultrasound. This objective technique may limit the variations in diagnosing morbidly adherent placenta because of the subjectivity of 2-dimensional ultrasound interpretations.
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX. Electronic address: ziad.haidar1@gmail.com.
authors.forename: Ziad A
authors.initials: ZA
authors.lastname: Haidar
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX; The Fetal Center, Children's Memorial Hermann Hospital, Houston, TX. Electronic address: Ramesha.Papanna@uth.tmc.edu.
authors.forename: Ramesha
authors.initials: R
authors.lastname: Papanna
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX.
authors.forename: Baha M
authors.initials: BM
authors.lastname: Sibai
authors.affiliation: Department of Pathology and Laboratory Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX.
authors.forename: Nina
authors.initials: N
authors.lastname: Tatevian
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX.
authors.forename: Oscar A
authors.initials: OA
authors.lastname: Viteri
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX.
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Vowels
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX.
authors.forename: Sean C
authors.initials: SC
authors.lastname: Blackwell
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX; The Fetal Center, Children's Memorial Hermann Hospital, Houston, TX.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Moise
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D010923:Placenta Previa / Q000000981:diagnostic imaging*; D018457:Placenta, Retained / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011446:Prospective Studies; D058996:Quality Improvement; D018608:Ultrasonography, Doppler; D018084:Ultrasonography, Interventional; D016216:Ultrasonography, Prenatal / Q000379:methods* / Q000592:standards
keywords: 2-dimensional; 3-dimensional; cesarean delivery; invasive; morbidly adherent placenta; placenta accreta; placenta previa; power Doppler; prenatal diagnosis; ultrasound