Ultrasound predictors of placental invasion: the Placenta Accreta Index

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Abstract

OBJECTIVE: We sought to apply a standardized evaluation of ultrasound parameters for the prediction of placental invasion in a high-risk population.

STUDY DESIGN: This was a retrospective review of gravidas with ≥1 prior cesarean delivery who received an ultrasound diagnosis of placenta previa or low-lying placenta in the third trimester at our institution from 1997 through 2011. Sonographic images were reviewed by an investigator blinded to pregnancy outcome and sonography reports. Parameters assessed included loss of retroplacental clear zone, irregularity and width of uterine-bladder interface, smallest myometrial thickness, presence of lacunar spaces, and bridging vessels. Diagnosis of placental invasion was based on histologic confirmation. Statistical analyses were performed using linear logistic regression and multiparametric analyses to generate a predictive equation evaluated using a receiver operating characteristic curve.

RESULTS: Of 184 gravidas who met inclusion criteria, 54 (29%) had invasion confirmed on hysterectomy specimen. All sonographic parameters were associated with placental invasion (P < .001). Constructing a receiver operating characteristic curve, the combination of smallest sagittal myometrial thickness, lacunae, and bridging vessels, in addition to number of cesarean deliveries and placental location, yielded an area under the curve of 0.87 (95% confidence interval, 0.80-0.95). Using logistic regression, a predictive equation was generated, termed the "Placenta Accreta Index." Each parameter was weighted to create a 9-point scale in which a score of 0-9 provided a probability of invasion that ranged from 2-96%, respectively.

CONCLUSION: Assignment of the Placenta Accreta Index may be helpful in predicting individual patient risk for morbidly adherent placenta.

Original languageEnglish (US)
JournalAmerican Journal of Obstetrics and Gynecology
Volume212
Issue number3
DOIs
StatePublished - Mar 1 2015

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Placenta Accreta
ROC Curve
Placenta
Logistic Models
Placenta Previa
Third Pregnancy Trimester
Pregnancy Outcome
Hysterectomy
Area Under Curve
Linear Models
Ultrasonography
Urinary Bladder
Regression Analysis
Research Personnel
Confidence Intervals
Population

Keywords

  • accreta
  • invasion
  • ultrasound

ASJC Scopus subject areas

  • Medicine(all)

Cite this

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title = "Ultrasound predictors of placental invasion: the Placenta Accreta Index",
abstract = "OBJECTIVE: We sought to apply a standardized evaluation of ultrasound parameters for the prediction of placental invasion in a high-risk population.STUDY DESIGN: This was a retrospective review of gravidas with ≥1 prior cesarean delivery who received an ultrasound diagnosis of placenta previa or low-lying placenta in the third trimester at our institution from 1997 through 2011. Sonographic images were reviewed by an investigator blinded to pregnancy outcome and sonography reports. Parameters assessed included loss of retroplacental clear zone, irregularity and width of uterine-bladder interface, smallest myometrial thickness, presence of lacunar spaces, and bridging vessels. Diagnosis of placental invasion was based on histologic confirmation. Statistical analyses were performed using linear logistic regression and multiparametric analyses to generate a predictive equation evaluated using a receiver operating characteristic curve.RESULTS: Of 184 gravidas who met inclusion criteria, 54 (29{\%}) had invasion confirmed on hysterectomy specimen. All sonographic parameters were associated with placental invasion (P < .001). Constructing a receiver operating characteristic curve, the combination of smallest sagittal myometrial thickness, lacunae, and bridging vessels, in addition to number of cesarean deliveries and placental location, yielded an area under the curve of 0.87 (95{\%} confidence interval, 0.80-0.95). Using logistic regression, a predictive equation was generated, termed the {"}Placenta Accreta Index.{"} Each parameter was weighted to create a 9-point scale in which a score of 0-9 provided a probability of invasion that ranged from 2-96{\%}, respectively.CONCLUSION: Assignment of the Placenta Accreta Index may be helpful in predicting individual patient risk for morbidly adherent placenta.",
keywords = "accreta, invasion, ultrasound",
author = "Rac, {Martha W.F.} and Dashe, {Jodi S.} and Wells, {C. Edward} and Elysia Moschos and McIntire, {Donald D.} and Twickler, {Diane M.}",
year = "2015",
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T1 - Ultrasound predictors of placental invasion

T2 - the Placenta Accreta Index

AU - Rac, Martha W.F.

AU - Dashe, Jodi S.

AU - Wells, C. Edward

AU - Moschos, Elysia

AU - McIntire, Donald D.

AU - Twickler, Diane M.

PY - 2015/3/1

Y1 - 2015/3/1

N2 - OBJECTIVE: We sought to apply a standardized evaluation of ultrasound parameters for the prediction of placental invasion in a high-risk population.STUDY DESIGN: This was a retrospective review of gravidas with ≥1 prior cesarean delivery who received an ultrasound diagnosis of placenta previa or low-lying placenta in the third trimester at our institution from 1997 through 2011. Sonographic images were reviewed by an investigator blinded to pregnancy outcome and sonography reports. Parameters assessed included loss of retroplacental clear zone, irregularity and width of uterine-bladder interface, smallest myometrial thickness, presence of lacunar spaces, and bridging vessels. Diagnosis of placental invasion was based on histologic confirmation. Statistical analyses were performed using linear logistic regression and multiparametric analyses to generate a predictive equation evaluated using a receiver operating characteristic curve.RESULTS: Of 184 gravidas who met inclusion criteria, 54 (29%) had invasion confirmed on hysterectomy specimen. All sonographic parameters were associated with placental invasion (P < .001). Constructing a receiver operating characteristic curve, the combination of smallest sagittal myometrial thickness, lacunae, and bridging vessels, in addition to number of cesarean deliveries and placental location, yielded an area under the curve of 0.87 (95% confidence interval, 0.80-0.95). Using logistic regression, a predictive equation was generated, termed the "Placenta Accreta Index." Each parameter was weighted to create a 9-point scale in which a score of 0-9 provided a probability of invasion that ranged from 2-96%, respectively.CONCLUSION: Assignment of the Placenta Accreta Index may be helpful in predicting individual patient risk for morbidly adherent placenta.

AB - OBJECTIVE: We sought to apply a standardized evaluation of ultrasound parameters for the prediction of placental invasion in a high-risk population.STUDY DESIGN: This was a retrospective review of gravidas with ≥1 prior cesarean delivery who received an ultrasound diagnosis of placenta previa or low-lying placenta in the third trimester at our institution from 1997 through 2011. Sonographic images were reviewed by an investigator blinded to pregnancy outcome and sonography reports. Parameters assessed included loss of retroplacental clear zone, irregularity and width of uterine-bladder interface, smallest myometrial thickness, presence of lacunar spaces, and bridging vessels. Diagnosis of placental invasion was based on histologic confirmation. Statistical analyses were performed using linear logistic regression and multiparametric analyses to generate a predictive equation evaluated using a receiver operating characteristic curve.RESULTS: Of 184 gravidas who met inclusion criteria, 54 (29%) had invasion confirmed on hysterectomy specimen. All sonographic parameters were associated with placental invasion (P < .001). Constructing a receiver operating characteristic curve, the combination of smallest sagittal myometrial thickness, lacunae, and bridging vessels, in addition to number of cesarean deliveries and placental location, yielded an area under the curve of 0.87 (95% confidence interval, 0.80-0.95). Using logistic regression, a predictive equation was generated, termed the "Placenta Accreta Index." Each parameter was weighted to create a 9-point scale in which a score of 0-9 provided a probability of invasion that ranged from 2-96%, respectively.CONCLUSION: Assignment of the Placenta Accreta Index may be helpful in predicting individual patient risk for morbidly adherent placenta.

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