前置胎盘

前置胎盘（placenta praevia, PP）是一种罕见的妊娠并发症。通常由于其他原因进行常规超声检查时确诊，但也可能在妊娠中期或晚期因无痛性阴道出血就诊。

如果胎盘直接覆盖宫颈口，则归为前置胎盘；如果胎盘边缘距离宫颈口 <2 cm，则归为低置胎盘。

前置胎盘导致的出血可能为（或变为）大出血，应采取适当的监测措施。对于有活动性阴道出血的女性，在确切知道胎盘位置之前，不应进行阴道指诊检查。

早期超声所见大多数前置胎盘会自行恢复。

对于 36 孕周后前置胎盘持续存在的所有病例，通常需要进行剖宫产。剖宫产可能引发大出血，还可能需要进行剖宫子宫切除术（或子宫动脉栓塞，或其他介入性放射学操作），且应仅由有经验的医生施行手术。

前置胎盘 (PP) 定义为胎盘覆盖子宫颈口。[1]Jain V, Bos H, Bujold E; Society of Obstetricians and Gynaecologists of Canada. Guideline no. 402: diagnosis and management of placenta previa. J Obstet Gynaecol Can. 2020 Jul;42(7):906-17.e1. http://www.ncbi.nlm.nih.gov/pubmed/32591150?tool=bestpractice.com [2]Royal College of Obstetricians and Gynaecologists. Placenta praevia and placenta accreta: diagnosis and management. Green-top guideline no. 27a. Sep 2018 [internet publication]. https://www.rcog.org.uk/en/guidelines-research-services/guidelines/gtg27a [3]Reddy UM, Abuhamad AZ, Levine D, et al. Fetal imaging: executive summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, American Institute of Ultrasound in Medicine, American College of Obstetricians and Gynecologists, American College of Radiology, Society for Pediatric Radiology, and Society of Radiologists in Ultrasound Fetal Imaging Workshop. J Ultrasound Med. 2014 May;33(5):745-57. http://www.ncbi.nlm.nih.gov/pubmed/24764329?tool=bestpractice.com 在中期妊娠诊断出的前置胎盘很可能随着妊娠进程而恢复。[1]Jain V, Bos H, Bujold E; Society of Obstetricians and Gynaecologists of Canada. Guideline no. 402: diagnosis and management of placenta previa. J Obstet Gynaecol Can. 2020 Jul;42(7):906-17.e1. http://www.ncbi.nlm.nih.gov/pubmed/32591150?tool=bestpractice.com [3]Reddy UM, Abuhamad AZ, Levine D, et al. Fetal imaging: executive summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, American Institute of Ultrasound in Medicine, American College of Obstetricians and Gynecologists, American College of Radiology, Society for Pediatric Radiology, and Society of Radiologists in Ultrasound Fetal Imaging Workshop. J Ultrasound Med. 2014 May;33(5):745-57. http://www.ncbi.nlm.nih.gov/pubmed/24764329?tool=bestpractice.com 在有瘢痕子宫（大多由于既往剖宫产）的女性中，前置胎盘可能引起胎盘植入性疾病（先前称为异常胎盘粘连和病态胎盘粘连），即胎盘附着在子宫肌层。[4]American College of Obstetricians and Gynecologists / Society for Maternal-Fetal Medicine. ACOG SMFM obstetric care consensus #7: placenta accreta spectrum. Dec 2018 [internet publication]. https://www.smfm.org/publications/266-acog-smfm-occ-7-placenta-accreta-spectrum 前置血管是一种相关疾病，其胎儿血管位于子宫颈内口之上。[5]Society for Maternal-Fetal Medicine. SMFM consult series #44: management of bleeding in the late preterm period. Oct 2017 [internet publication]. https://www.smfm.org/publications/249-smfm-consult-series-44-management-of-bleeding-in-the-late-preterm-period

在本专题中，我们将所有类型的侵入性胎盘称为胎盘植入性疾病。[4]American College of Obstetricians and Gynecologists / Society for Maternal-Fetal Medicine. ACOG SMFM obstetric care consensus #7: placenta accreta spectrum. Dec 2018 [internet publication]. https://www.smfm.org/publications/266-acog-smfm-occ-7-placenta-accreta-spectrum 一般有 3 种定义的变异类型，包括：胎盘粘连（绒毛膜绒毛附着在子宫肌层而不是局限在子宫底蜕膜）、胎盘植入（绒毛膜绒毛侵入到子宫肌层内）和穿透性胎盘（绒毛膜绒毛穿过子宫肌层，有时进入相邻组织）。[4]American College of Obstetricians and Gynecologists / Society for Maternal-Fetal Medicine. ACOG SMFM obstetric care consensus #7: placenta accreta spectrum. Dec 2018 [internet publication]. https://www.smfm.org/publications/266-acog-smfm-occ-7-placenta-accreta-spectrum 尽管这些区别对主任医师很重要，但它们不会改变基础医护人员的管理决策。[Figure caption and citation for the preceding image starts]: 22 孕周时的前置胎盘（以往称为完全前置胎盘）来自 Janet R. Albers 博士的教学材料 [Citation ends].