检查 可以采用经阴道、经腹部或经会阴(在大多数情况下没用,如果可行,也是一种选择,但有导致阴道出血和宫颈扩张的顾虑)超声检查。
首选经阴道超声(但如果由没经验的操作者实施,也可能导致损伤)。[15]Oppenheimer L; Society of Obstetricians and Gynaecologists of Canada. Diagnosis and management of placenta previa. J Obstet Gynaecol Can. 2007;29:261-266.http://www.jogc.com/article/S1701-2163%2816%2932401-X/pdfhttp://www.ncbi.nlm.nih.gov/pubmed/17346497?tool=bestpractice.com[37]American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 101: ultrasonography in pregnancy. Obstet Gynecol. 2009;113:451-461.http://www.ncbi.nlm.nih.gov/pubmed/19155920?tool=bestpractice.com[39]Royal College of Obstetricians and Gynaecologists. Placenta praevia, placenta praevia accreta and vasa praevia: diagnosis and management. Green-top guideline no. 27. January 2011. http://www.rcog.org.uk/ (last accessed 31 July 2017).https://www.rcog.org.uk/globalassets/documents/guidelines/gtg_27.pdf
如果怀疑前置胎盘,应转诊进行彩色多普勒血流超声检查。[37]American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 101: ultrasonography in pregnancy. Obstet Gynecol. 2009;113:451-461.http://www.ncbi.nlm.nih.gov/pubmed/19155920?tool=bestpractice.com[38]Dashe JS, McIntire DD, Ramus RM, et al. Persistence of placenta previa according to gestational age at ultrasound detection. Obstet Gynecol. 2002;99:692-697.http://www.ncbi.nlm.nih.gov/pubmed/11978274?tool=bestpractice.com[41]Abramowicz JS, Sheiner E. In utero imaging of the placenta: importance for diseases of pregnancy. Placenta. 2007;28(suppl A):S14-S22.http://www.ncbi.nlm.nih.gov/pubmed/17383721?tool=bestpractice.com[48]Bhide A, Prefumo F, Moore J, et al. Placental edge to internal os distance in the late third trimester and mode of delivery in placenta praevia. BJOG. 2003;110:860-864.http://www.ncbi.nlm.nih.gov/pubmed/14511970?tool=bestpractice.com[49]Oppenheimer L, Holmes P, Simpson N, et al. Diagnosis of low-lying placenta: can migration in the third trimester predict outcome? Ultrasound Obstet Gynecol. 2001;18:100-102.http://www.ncbi.nlm.nih.gov/pubmed/11529986?tool=bestpractice.com[50]Predanic M, Perni SC, Baergen RN, et al. A sonographic assessment of different patterns of placenta previa "migration" in the third trimester of pregnancy. J Ultrasound Med. 2005;24:773-780.http://www.ncbi.nlm.nih.gov/pubmed/15914681?tool=bestpractice.com[51]Olive EC, Roberts CL, Nassar N, et al. Test characteristics of placental location screening by transabdominal ultrasound at 18-20 weeks. Ultrasound Obstet Gynecol. 2006;28:944-949.http://www.ncbi.nlm.nih.gov/pubmed/17121427?tool=bestpractice.com[52]Comstock CH, Love JJ, Bronsteen RA, et al. Sonographic detection of placenta accreta in the second and third trimesters of pregnancy. Am J Obstet Gynecol. 2004;190:1135-1140.http://www.ncbi.nlm.nih.gov/pubmed/15118654?tool=bestpractice.com[53]Adeyomoye AA, Ola ER, Arogundade RA, et al. Comparison of the accuracy of trans-abdominal sonography (TAS) and transperineal sonography (TPS) in the diagnosis of placenta praevia. Niger Postgrad Med J. 2006;13:21-25.http://www.ncbi.nlm.nih.gov/pubmed/16633374?tool=bestpractice.com
常规提供甲胎蛋白 (AFP) 检测,作为三联或四联检测的一部分,用于筛查神经管缺陷和其他先天性异常。如果 AFP 水平异常的患者被诊断为妊娠中期或妊娠晚期前置胎盘,则应高度怀疑侵袭性胎盘的可能性,并考虑进行超声扫描。[47]Gagnon A, Wilson RD, Audibert F, et al; Society of Obstetricians and
Gynaecologists of Canada Genetics Committee. Obstetrical complications associated
with abnormal maternal serum markers analytes. J Obstet Gynaecol Can. 2008;30:918-949.http://sogc.org/wp-content/uploads/2013/01/gui217CPG0810.pdfhttp://www.ncbi.nlm.nih.gov/pubmed/19038077?tool=bestpractice.com
如果通过超声检查不能确切排除胎盘附着异常,则应对胎盘进行 MRI 检查。[15]Oppenheimer L; Society of Obstetricians and Gynaecologists of Canada. Diagnosis and management of placenta previa. J Obstet Gynaecol Can. 2007;29:261-266.http://www.jogc.com/article/S1701-2163%2816%2932401-X/pdfhttp://www.ncbi.nlm.nih.gov/pubmed/17346497?tool=bestpractice.com[37]American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 101: ultrasonography in pregnancy. Obstet Gynecol. 2009;113:451-461.http://www.ncbi.nlm.nih.gov/pubmed/19155920?tool=bestpractice.com[39]Royal College of Obstetricians and Gynaecologists. Placenta praevia, placenta praevia accreta and vasa praevia: diagnosis and management. Green-top guideline no. 27. January 2011. http://www.rcog.org.uk/ (last accessed 31 July 2017).https://www.rcog.org.uk/globalassets/documents/guidelines/gtg_27.pdf[41]Abramowicz JS, Sheiner E. In utero imaging of the placenta: importance for diseases of pregnancy. Placenta. 2007;28(suppl A):S14-S22.http://www.ncbi.nlm.nih.gov/pubmed/17383721?tool=bestpractice.com