[1] Jauniaux E, Chantraine F, Silver RM, et al. for the FIGO Placenta Accreta Diagnosis and Management Expert Consensus Panel. FIGO consensus guidelines on placenta accreta spectrum disorders: Epidemiology. Int J Gynecol Obstet, 2018; 140, 265−73. doi:  10.1002/ijgo.12407
[2] Wu S, Kocherginsky M, Hibbard JU. Abnormal placentation: Twenty-year analysis. Am J Obstet Gynecol, 2005; 192, 1458−61. doi:  10.1016/j.ajog.2004.12.074
[3] Fan D, Li S, Wu S, et al. Prevalence of abnormally invasive placenta among deliveries in mainland China: A PRISMA-compliant Systematic Review and Meta-analysis. Medicine (Baltimore), 2017; 96, e6636. doi:  10.1097/MD.0000000000006636
[4] Klar M, Laub M, Schulte-Moenting J, et al. Clinical risk factors for complete and partial placental retention: a case-control study. J Perinat Med, 2014; 41529e34.
[5] Jauniaux E, Bunce C, Grønbeck L, et al. Prevalence and main outcomes of placenta accreta spectrum: a systematic review and metaanalysis. Am J Obstet Gynecol, 2019; 9, e031193.
[6] Wang Y, Gao Y, Zhao YY, et al. Ultrasonographic diagnosis of severe placental invasion. J Obestet and Gynecol Res, 2018; 44, 448−55. doi:  10.1111/jog.13531
[7] Chong. YW, Zhang AQ, Wang Y, et al. Value of ultrasonic scoring system for predicting risks of placenta accreta. Chin J Perinat Med, sept, 2016; 19, 705−9. (In Chinese
[8] Chong, Y, Zhang AQ Zhao YY., et al. An ultrasonic scoring system to predict the prognosis of placenta accreta. Medicine, 2018; 97, e12111. doi:  10.1097/MD.0000000000012111
[9] Committee on Practice Bulletins-Obstetrics. Practice Bulletin No. 183: Postpartum Hemorrhage. Obstet Gynecol, 2017; 130, e168−86. doi:  10.1097/AOG.0000000000002351
[10] Chow S, Shao J, Wang H. 2008. Sample Size Calculations in Clinical Research. 2nd Ed. Chapman & Hall/CRC Biostatistics Series. p 89.
[11] Pagani G, Cali G, Acharya G, et al. Diagnostic accuracy of ultrasound in detecting the severity of abnormally invasive placentation: a systematic review and meta-analysis. Acta Obstet Gynecol Scand, 2018; 97, 25−37. doi:  10.1111/aogs.13238
[12] Rac MW, Dashe JS, Wells CE, et al. Ultrasound predictors of placental invasion: the Placenta Accreta Index. Am J Obstet Gynecol, 2015; 212, 343.e1−343.e3437. doi:  10.1016/j.ajog.2014.10.022
[13] Tovbin J, Melcer Y, Shor S, et al. Prediction of morbidly adherent placenta using a scoring system. Ultrasound Obstet Gynecol, 2016; 48, 504−10. doi:  10.1002/uog.15813
[14] Marsoosi V, Ghotbizadeh F, Hashemi N, et al. Development of a scoring system for prediction of placenta accreta and determine the accuracy of its results. J Matern Fetal Neonatal Med, 2020; 33, 1824−30. doi:  10.1080/14767058.2018.1531119
[15] Weiniger CF, Einav S, Deutsch L, et al. Outcomes of prospectively collected consecutive cases of antenatal suspected placenta accreta. Int J Obstet Anesth, 2013; 22, 273−9. doi:  10.1016/j.ijoa.2013.04.014
[16] Cali G, Forlani F, Lees C, et al. Prenatal ultrasound staging system for placenta accreta spectrum disorders. Ultrasound Obstet Gynecol, 2019; 53, 752−60.
[17] Dall'Asta A, Calì G, Forlani F, et al. Evaluation of perioperative complications using a newly described staging system for placenta accreta spectrum. Eur J Obstet Gynecol Reprod Biol, 2020; 250, 54−60. doi:  10.1016/j.ejogrb.2020.04.038
[18] Gilboa Y, Spira M, Mazaki-Tovi S, et al. A novel sonographic scoring system for antenatal risk assessment of obstetric complications in suspected morbidly adherent placenta. J Ultrasound Med, 2015; 34, 561−7. doi:  10.7863/ultra.34.4.561
[19] Obstetric Care Consensus No. Obstetric Care Consensus No. 7: Placenta Accreta Spectrum. Obstet Gynecol, 2018; 132, e259−75. doi:  10.1097/AOG.0000000000002983