Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas, USA.
J Ultrasound Med. 2021 Aug;40(8):1523-1532. doi: 10.1002/jum.15530. Epub 2020 Oct 14.
The placenta accreta spectrum (PAS) incidence has risen substantially over the past century, paralleling a rise in cesarean delivery (CD) rates. Prenatal diagnosis of PAS improves maternal outcomes. The Placenta Accreta Index (PAI) is a standardized approach to prenatal diagnosis of PAS incorporating clinical risk and ultrasound (US) findings suggestive of placental invasion. We sought to validate the PAI for prediction of PAS in pregnancies with prior CD.
This work was a retrospective cohort study of pregnancies with 1 or more prior CDs that received a US diagnosis of placenta previa or low-lying placenta in the third trimester. Images of third-trimester US with a complete placental evaluation were read by 2 blinded physicians, and the PAI was applied. Surgical outcomes and pathologic findings were reviewed. Placenta accreta spectrum was diagnosed if clinical evidence of invasion was seen at time of delivery or if any placental invasion was identified histologically. International Federation of Gynecology and Obstetrics criteria were used.
A total of 194 women met inclusion criteria. Cesarean hysterectomy was performed in 92 (47%), CD in 97 (50%), and vaginal delivery in 5 (3%). Of those who underwent hysterectomy, PAS was histologically confirmed in 79 (85%) pregnancies. Of the remaining 13 who underwent hysterectomy, all met International Federation of Gynecology and Obstetrics grade 1 clinical criteria for PAS. With a threshold of greater than 4, the PAI has a sensitivity of 87%, specificity of 77%, positive predictive value of 72%, and negative predictive value of 90% for PAS diagnosis.
Contemporaneous application of the PAI, a standardized approach to US diagnosis, is useful in the prenatal prediction of PAS.
胎盘植入谱系（PAS）的发病率在过去一个世纪中大幅上升，与剖宫产率的上升平行。PAS 的产前诊断可改善母婴结局。胎盘植入指数（PAI）是一种标准化的 PAS 产前诊断方法，结合了临床风险和提示胎盘浸润的超声（US）发现。我们旨在验证 PAI 对既往剖宫产妊娠 PAS 的预测价值。
这是一项回顾性队列研究，纳入了既往有 1 次或多次剖宫产史且在孕晚期超声诊断为前置胎盘或胎盘低位的妊娠。由 2 名盲法医师阅读具有完整胎盘评估的孕晚期 US 图像，并应用 PAI。回顾手术结局和病理发现。如果在分娩时出现侵袭性临床表现，或组织学上发现任何胎盘浸润，则诊断为 PAS。采用国际妇产科联合会（FIGO）标准。
共有 194 名妇女符合纳入标准。92 名（47%）行剖宫产子宫切除术，97 名（50%）行剖宫产术，5 名（3%）行阴道分娩。在接受子宫切除术的患者中，79 例（85%）的 PAS 经组织学证实。在其余 13 例接受子宫切除术的患者中，所有患者均符合 PAS 的国际妇产科联合会（FIGO）1 级临床标准。PAI 阈值大于 4 时，其诊断 PAS 的敏感度为 87%，特异度为 77%，阳性预测值为 72%，阴性预测值为 90%。
在产前诊断中，同时应用 PAI 这一标准化的超声诊断方法有助于预测 PAS。
