Abstract
OBJECTIVE: To evaluate national and international obstetric ultrasound guidelines regarding their recommendations for vasa previa (VP) screening, and to assess the consistency, scope and evidence base of the recommendations.
METHODS: We conducted a comprehensive review of accessible national obstetric imaging guidelines from 15 countries worldwide, as well as two international guidelines by the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG). Guidelines were assessed for whether they explicitly mentioned VP, recommended screening for VP or incorporated VP detection strategies, such as placental cord insertion assessment, color flow Doppler assessment of the lower uterine segment or third-trimester transvaginal ultrasound with color flow Doppler in patients with second-trimester placenta previa or low-lying placenta. Additionally, we evaluated whether any national societies or international organizations had specific guidelines on VP, which were then assessed for whether they included recommendations for VP screening and outlined specific screening policies or strategies.
RESULTS: Of 20 national and two international obstetric imaging guidelines reviewed, 12 mentioned VP and none explicitly recommended routine screening for VP in pregnant individuals. Nine national obstetric imaging guidelines recommended routine assessment of the placental cord insertion, while none endorsed routine color flow Doppler assessment of the lower uterine segment. Five national guidelines recommended third-trimester transvaginal ultrasound examination with color flow Doppler to rule out VP in pregnancies with a second-trimester low-lying placenta or placenta previa. In our search, only five national societies were found to have developed dedicated VP guidelines, although some of their recommendations were inconsistent with recent evidence. For example, the 2019 guideline from the Royal College of Obstetricians and Gynaecologists in the UK does not recommend routine VP screening, citing insufficient evidence and an uncertain balance of benefit vs harm.
CONCLUSIONS: Despite the high mortality rate associated with undiagnosed VP and the mounting evidence supporting the feasibility of screening, many national and international obstetric imaging guidelines either omit mention of VP or fall short of recommending a structured screening approach. Given the demonstrated accuracy of VP screening, its remarkable impact in reducing the rate of VP-related stillbirth and the minimal additional resources required for VP detection strategies, current imaging guidelines should be updated to incorporate evidence-based VP screening strategies into routine obstetric imaging protocols to reduce preventable perinatal deaths. © 2026 International Society of Ultrasound in Obstetrics and Gynecology.