Placenta praevia

Anatomical criteria (placental position in relation to cervical os)[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

Diagnostic criteria are based on ultrasound findings at >18 to 20 weeks' gestation:

• Placenta praevia is diagnosed if the placenta is overlying the cervical os on ultrasound.[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

• Low-lying placenta is diagnosed if the edge of the placenta is <2 cm from the cervical os.[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