Guideline sources The following summarized guidelines for the evaluation and management of vasa previa are prepared by our editorial team based on guidelines from the Society of Obstetricians and Gynaecologists of Canada (SOGC 2023; 2017), the Royal College of Obstetricians and Gynaecologists (RCOG 2019), and the Society for Maternal-Fetal Medicine (SMFM 2015). 1 2 3 4 Guidelines 1. Screening and diagnosis Indications for screening: As per SOGC 2023 guidelines, obtain targeted screening for vasa previa in all pregnant individuals with a risk factor. B As per RCOG 2019 guidelines: Insufficient evidence to recommend universal screening for vasa previa at the time of the mid-pregnancy routine fetal U/S in the general population. I Insufficient evidence to recommend targeted mid-pregnancy ultrasound assessment of pregnancies at higher risk of vasa previa. I Diagnosis: Classify fetal vessels < 2 cm from the cervical os as vasa previa. B Classify vessels between 2 and 5 cm from the cervical os as low-lying fetal vessels. B https://web.pathway.md/diseases/recjLyYNiN1cmSjQd 1/4 6/29/23, 3:23 AM Vasa previa Pathway 2. Diagnostic investigations Ultrasound: As per SOGC 2023 guidelines, assess the placental cord insertion site in all pregnant individuals at the routine second-trimester fetal anatomical scan. B Show 3 more As per RCOG 2019 guidelines: Obtain ultrasound at the time of the routine fetal anomaly scan for the diagnosis of vasa previa due to its high diagnostic accuracy with a low false-positive rate. B Obtain a combination of transabdominal and transvaginal color Doppler ultrasound for better diagnostic accuracy. B Obtain ultrasound in the third trimester for confirmation of persistence of vasa previa to avoid unnecessary anxiety, admissions, prematurity, and C-section. B As per SMFM 2015 guidelines: Evaluate placental location and the relationship between the placenta and internal cervical os during the second-trimester ultrasound and document the placental cord insertion site if technically possible. E Obtain follow-up ultrasound at 32 weeks of gestation in patients diagnosed with placenta previa or low-lying placenta at mid-trimester ultrasound. Obtain transvaginal ultrasound with color and pulsed Doppler to rule out vasa previa since placenta previa detected in the middle of the second trimester that later resolves and low-lying placenta (even if it later resolves) are associated with vasa previa and consequently high perinatal mortality rates. B 3. Diagnostic procedures Pathological examination: perform placental pathological examination to confirm the diagnosis of vasa previa, in particular when stillbirth has occurred or where there has been acute fetal compromise during delivery. B 4. Medical management Antenatal hospitalization: As per SOGC 2023 guidelines: Consider offering hospitalization at 32 weeks of gestation in patients with vasa previa and before 32 weeks in patients with additional risk factors for early delivery (such as multiple gestation or a short cervix). C Consider ensuring timely access to an operating room, an obstetrician, an anesthetist, and an appropriate neonatal ICU when deciding the location of admission for observation or delivery. C As per RCOG 2019 guidelines, individualize the decision for prophylactic hospitalization from 30-32 weeks of gestation in patients with confirmed vasa previa based on a combination of factors, including multiple pregnancy, antenatal bleeding, and threatened premature labor. B https://web.pathway.md/diseases/recjLyYNiN1cmSjQd 2/4 6/29/23, 3:23 AM Vasa previa Pathway As per SMFM 2015 guidelines, consider offering antenatal hospitalization in patients with prenatal diagnosis of vasa previa from 30-34 weeks of gestation. C Antenatal corticosteroids: As per RCOG 2019 guidelines, administer corticosteroids for fetal lung maturity from 32 weeks of gestation due to the increased risk of preterm delivery. B As per SOGC 2017 guidelines, consider administering corticosteroids at 28-32 weeks of gestation to promote fetal lung maturation. C As per SMFM 2015 guidelines, consider administering antenatal corticosteroids from 28-32 weeks of gestation. C 5. Surgical interventions Cesarean delivery, planned: As per SOGC 2023 guidelines, offer Cesarean delivery at 35+0 to 35+6 weeks in patients with vasa previa and singleton pregnancy. Consider offering earlier delivery in the presence of additional risk factors for preterm delivery. B Show 2 more As per RCOG 2019 guidelines, do not delay delivery while trying to confirm the diagnosis, particularly if there is evidence that fetal wellbeing is compromised because of the speed at which fetal exsanguination can occur and the high perinatal mortality rate associated with ruptured vasa previa. D Show 2 more As per SMFM 2015 guidelines, consider offering scheduled Cesarean delivery in patients with vasa previa from 34-37 weeks of gestation. C Cesarean delivery, emergency: As per RCOG 2019 guidelines: Perform Cesarean delivery without delay in patients with vasa previa developing premature rupture of membranes and/or labor at viable gestational ages. B Perform emergency Cesarean delivery and neonatal resuscitation )including administering blood transfusion if required) in patients with ruptured vasa previa diagnosed during labor. B As per SMFM 2015 guidelines, perform Cesarean delivery in patients with pregnancy at viable gestational ages and an antenatal diagnosis of vasa previa developing premature rupture of membranes or labor. B Cesarean delivery (setting of care): perform Cesarean delivery in patients with vasa previa at a center capable of providing immediate neonatal blood transfusion. B References 1. Society of Maternal-Fetal SMFM Publications Committee, Rachel G Sinkey, Anthony O Odibo et al. #37 Diagnosis and management of vasa previa. Am J Obstet Gynecol. 2015 Nov;213 5 615 9. Open https://web.pathway.md/diseases/recjLyYNiN1cmSjQd 3/4 6/29/23, 3:23 AM Vasa previa Pathway 2. Erm Jauniaux, Z Alfirevic, A G Bhide et al. Vasa Praevia: Diagnosis and Management: Green-top Guideline No. 27b. BJOG. 2019 Jan;126 1):e49-e61. Open 3. Robert Gagnon. No. 231 Guidelines for the Management of Vasa Previa. J Obstet Gynaecol Can. 2017 Oct;39 10):e415-e421. Open 4. Venu Jain, Robert Gagnon. Guideline No. 439 Diagnosis and Management of Vasa Previa. J Obstet Gynaecol Can. 2023 May 18;S1701 2163 23 00378 X. Open https://web.pathway.md/diseases/recjLyYNiN1cmSjQd 4/4