| Objective: This study aimed to establish a comprehensive scoring system based on maternal characteristics and two-dimensional ultrasound signs to predicet different grades of PAS.Then,we tried to detect whether uterine artery(UA)blood flow parameters and three-dimensional power Doppler(3D-PDU)placental flow parameters are different between PAS group and Non-PAS group.Method: 1.Establishment of PAS scoring system by retrospective analysis.(1)Patients inclusing: From January 2014 to August 2017,pregnant women who underwent routine ultrasound examination in the third trimester of pregnancy were collected retrospectively.From September 2017 to November 2018 pregnant women who underwent routine ultrasound examination in the third trimester of pregnancy were collected prospectively as test group.Inclusion criteria: single pregnancy;gestational age ? 28 weeks;regular menstrual cycle of pregnant women;delivery in our hospital;complete clinical,surgical and pathological records;the scanning was operated by a doctor who has experience in ultrasound more than 10 years.Exclusion criteria: intrauterine fetal death,fetal growth restriction or severe malformation;placental abruption;complicated with uterine leiomyoma and other lesions affecting image quality.Clinical or pathological diagnosis was used as the “gold standard”.(2)Data collection: We recorded whether there were abnormal placental lacunae(number of lacuna and lacuna maximum dimension),thinning or interruption of uteroplacental myometrium,sub-placental hypervascularity,bladder wall interruption,placental bulge,placenta previa and location of placenta.We also recorded maternal characteristics including age;parity;the number of previous vaginal deliveries,previous abortions and previous cesarean sections(CS);history of abnormal blood pressure and blood glucose;body mass index(BMI).(3)Statistical analysis: SPSS 22.0 was used for statistical analyses.Chi-square test was used to analyze the correlation between the characteristics and PAS.Multivariate logistic regression was used to analyze the independent risk factors of PAS.Then,multivariate logistic regression was also used to calculate the odd ratio(OR)of twodimensional ultrasound signs and independent risk factors.According to different methods of dividing OR values,all possible schemes were listed.The diagnostic power of various schemes was evaluated by receiver–operating characteristics(ROC)curves.Test group was used to further evaluated the sensitivity,Specificity,positive predictive value,negative predictive value,positive likelihood ratio and negative likelihood ratio of selected schemes.The best scheme of comprehensive scoring system would be determined.Than,we use the scoring system to distinguish Non-PAS and placenta accrete,placenta accrete and placenta increta,and placenta increta and placenta percreta,respectively.ROC curves were drawn to evaluate the power of the scoring system prediting different grads of PAS.2.Analysis of the correlation between uterine artery Doppler parameters and PAS by prospective study.(1)Patients inclusion: From September 2017 to November 2018 pregnant women who underwent routine ultrasound examination in the third trimester of pregnancy were collected prospectively.Inclusion criteria: single pregnancy;gestational age ? 28 weeks;regular menstrual cycle of pregnant women;delivery in our hospital;complete clinical,surgical and pathological records;the scanning was operated by a doctor who has experience in ultrasound more than 10 years.Exclusion criteria: intrauterine fetal death,fetal growth restriction or severe malformation;placental abruption;pregnancy-induced hypertension syndrome,complicated with uterine leiomyoma and other lesions affecting image quality.Clinical or pathological diagnosis was used as the “gold standard”.(2)Testing methods and parameters: Color doppler ultrasound were used to measure the values of Uterine artery pulsatility index(UA-PI),uterine artery resistance index(UA-RI)and uterine artery peak systolic period/peak diastolic period(UA-S/D)on pregnant women with informed consent.(3)Statistical analysis: Intra-class correlation coefficient(ICC)was used to test intraobserver reproducibility of the studied parameters.One-way analysis of covariance(ANCOVA)was conducted to test for group differences.The level of significance was set at 0.05.The statistically significant indexes were selected.3.The analysis of correlation between 3D-PDU placental perfusion parameters and PAS,and an integrated diagnostic system was established by prospective study.(1)Patients inclusion: From September 2017 to November 2018 pregnant women who underwent routine ultrasound examination in the third trimester of pregnancy were collected prospectively.Inclusion criteria: single pregnancy;gestational age ? 28 weeks;regular menstrual cycle of pregnant women;delivery in our hospital;complete clinical,surgical and pathological records;the scanning was operated by a doctor who has experience in ultrasound more than 10 years.Exclusion criteria: intrauterine fetal death,fetal growth restriction or severe malformation;placental abruption;pregnancy-induced hypertension syndrome,complicated with uterine leiomyoma and other lesions affecting image quality.Clinical or pathological diagnosis was used as the “gold standard”.(2)Testing methods and parameters: Vascularization index(VI),flow index(FI)and vascularization-flow index(VFI)of all placentas were measured by 3D-PDU.Intra-class correlation coefficient(ICC)was used to test intra-observer reproducibility of the studied parameters.(3)Testing methods and parameters: One-way analysis of covariance(ANCOVA)was conducted to test for group differences.The level of significance was set at 0.05.The statistically significant indexes were selected.Finally,the comprehensive scoring system combined with selected UA indexes and 3D-PDU indexes was used to diagnose PAS,and the diagnostic value was evaluated through ROC curve.Result: 1.In the first part,a total of 398 pregnant women were included.There were 90 cases were eventually diagnosed as PAS by clinical or pathological examinations while remaining 308 cases were non-PAS.Chi-square tests showed that age of pregnant women ? 32(p = 0.017),parity ? 4(p < 0.001),previous abortions ? 2(p < 0.001)and previous CS ? 1(p < 0.001)were related to the occurrence of PAS.Multivariate Logistic regression analysis showed that parity ? 4(p < 0.001),previous abortions ? 2(p < 0.001)and previous CS ? 1(p < 0.001)were independent risk factors for PAS.The best comprehensive scoring system based on maternal characteristics and ultrasonographic features was established as follows: the number of abnormal lacunae ? 3,2 points;lacuna maximum dimension ? 2 cm,5 points;sub-placental vascularity increase moderately,1 point;sub-placental vascularity increased extremely and disordered,3 points;bladder wall become rough or interrupt,9 points;placental bulge,9 points;placenta previa,8 points;anterior placenta,1 point; previous CS ? 1,1 point;parity ? 4,3 point;previous abortions ? 2,1 point.The area under the ROC curve of the comprehensive scoring system diagnosing PAS was 0.925(95% CI,0.89-1.00),sensitivity was 83.3%,specificity was 85.7%,positive predictive value was 6.6%,negative predictive value was 99.8%,positive likelihood ratio was 5.8 and negative likelihood ratio was 0.195.Using the scoring system to distinguish three grades of PAS: 8-13 points represented placenta accrete,and the sensitivity and specificity were 77.78% and 83.44%;14-20 points represented placenta increta,and the sensitivity and specificity were 56.06% and 88.89%;?21 points represented placenta percreta,and the sensitivity and specificity were 83.33% and 78.79%.2.In the second part,a total of 116 pregnant women were included.There were 36 cases were eventually diagnosed as PAS by clinical or pathological examinations while remaining 80 cases were non-PAS.ICC values of UA-PI,UA-RI and UAS/D were 0.958,0.925 and 0.950 respectively.All the Uterine Artery parameters showed a coefficient greater than 0.75 which represents great intra-observer agreement for the parameters.ANCOVA analysis showed that the estimated marginal mean of UA-PI,UA-RI and UA-S/D in PAS group were 0.54,0.40 and 1.64,respectively;the estimated marginal mean of UA-PI,UA-RI and UA-S/D in non-PAS group were 0.59,0.42 and 1.71 respectively after unifying the gestational weeks to 33.88 weeks.There were significant differences in UA-PI and UA-S/D between two groups(p = 0.018,p = 0.044),but no difference in uterine artery UARI(p = 0.123).3.In the third part,a total of 45 pregnant women were included.There were 23 cases were eventually diagnosed as PAS by clinical or pathological examinations while remaining 22 cases were non-PAS.ICC values of VI,FI and VFI were 0.998,0.987 and 0.994 respectively.All the 3D-PDU placental flow parameters showed a coefficient greater than 0.75 which represents great intra-observer agreement for the parameters.ANCOVA analysis showed that the estimated marginal mean of VI,FI and VFI in PAS group were 53.70,36.47 and 19.71,respectively;the estimated marginal mean of VI,FI and VFI in non-PAS group were 34.18,38.88 and 12.76 respectively after unifying the gestational weeks to 32.93 weeks.There were significant differences in VI and VFI between two groups(p < 0.001,p = 0.001),but no difference in uterine artery FI(p = 0.201).Conclusion: The comprehensive scoring system based on maternal characteristics and ultrasonographic features could predict the grades PAS effectively.There were significant differences in UA-PI,UA-S/D,VI and VFI between two groups.The further study can monitor the four parameters on every gestational week and find out the reference values of predition PAS,which can be potentially used to assist the scoring system to further improve the prediction rate of PAS. |
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