Abstract
Objectives
To describe the etiology of vasa previa and the risk factors and associated condition,
to identify the various clinical presentations of vasa previa, to describe the ultrasound
tools used in its diagnosis, and to describe the management of vasa previa.
Outcomes
Reduction of perinatal mortality, short-term neonatal morbidity, long-term infant
morbidity, and short-term and long-term maternal morbidity and mortality.
Evidence
Published literature on randomized trials, prospective cohort studies, and selected
retrospective cohort studies was retrieved through searches of PubMed or Medline,
CINAHL, and the Cochrane Library, using appropriate controlled vocabulary (e.g., selected
epidemiological studies comparing delivery by Caesarean section with vaginal delivery;
studies comparing outcomes when vasa previa is diagnosed antenatally vs. intrapartum)
and key words (e.g., vasa previa). Results were restricted to systematic reviews,
randomized control trials/controlled clinical trials, and observational studies. Searches
were updated on a regular basis and incorporated into the guideline to October 1,
2008. Grey (unpublished) literature was identified through searching the websites
of health technology assessment and health technology assessment-related agencies,
clinical practice guideline collections, clinical trial registries, and from national
and international medical specialty societies.
Values
The evidence collected was reviewed by the Diagnostic Imaging Committee and the Maternal
Fetal Medicine Committee of the Society of Obstetricians and Gynaecologists of Canada
(SOGC) and quantified using the evaluation of evidence guidelines developed by the
Canadian Task Force on Preventive Health Care.
Benefits, Harms, and Costs
The benefit expected from this guideline is facilitation of optimal and uniform care
for pregnancies complicated by vasa previa.
Sponsors: The Society of Obstetricians and Gynaecologists of Canada.
Summary Statement
A comparison of women who were diagnosed antenatally and those who were not shows
respective neonatal survival rates of 97% and 44%, and neonatal blood transfusion
rates of 3.4% and 58.5%, respectively. Vasa previa can be diagnosed antenatally, using
combined abdominal and transvaginal ultrasound and colour flow mapping; however, many
cases are not diagnosed, and not making such a diagnosis is still acceptable. Even
under the best circumstances the false positive rate is extremely low. (II-2)
Recommendations
- 1.If the placenta is found to be low lying at the routine second trimester ultrasound examination, further evaluation for placental cord insertion should be performed (II-2B).
- 2.Transvaginal ultrasound may be considered for all women at high risk for vasa previa, including those with low or velamentous insertion of the cord, bilobate or succenturiate placenta, or for those having vaginal bleeding, in order to evaluate the internal cervical os (II-2B).
- 3.If vasa previa is suspected, transvaginal ultrasound colour Doppler may be used to facilitate the diagnosis. Even with the use of transvaginal ultrasound colour Doppler, vasa previa may be missed (II-2B).
- 4.When vasa previa is diagnosed antenatally, an elective Caesarean section should be offered prior to the onset of labour (II-1A).
- 5.In cases of vasa previa, premature delivery is most likely; therefore, consideration should be given to administration of corticosteroids at 28 to 32 weeks to promote fetal lung maturation and to hospitalization at about 30 to 32 weeks (II-2B).
- 6.In a woman with an antenatal diagnosis of vasa previa, when there has been bleeding or premature rupture of membranes, the woman should be offered delivery in a birthing unit with continuous electronic fetal heart rate monitoring and, if time permits, a rapid biochemical test for fetal hemoglobin, to be done as soon as possible; if any of the above tests are abnormal, an urgent Caesarean section should be performed (III-B).
- 7.Women admitted with diagnosed vasa previa should ideally be transferred for delivery in a tertiary facility where a pediatrician and blood for neonatal transfusion are immediately available in case aggressive resuscitation of the neonate is necessary (II-3B).
- 8.Women admitted to a tertiary care unit with a diagnosis of vasa previa should have this diagnosis clearly identified on the chart, and all health care providers should be made aware of the potential need for immediate delivery by Caesarean section if vaginal bleeding occurs (III-B).
Key Words
Abbreviations:
HbF (fetal hemoglobin), IVF (in vitro fertilization), MRI (magnetic resonance imaging)To read this article in full you will need to make a payment
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Article info
Publication history
No. 231 (Reaffirmed October 2017)
Footnotes
This document reflects emerging clinical and scientific advances on the date issued, and is subject to change. The information should not be construed as dictating an exclusive course of treatment or procedure to be followed. Local institutions can dictate amendments to these opinions. They should be well-documented if modified at the local level. None of these contents may be reproduced in any form without prior written permission of the publisher.
Women have the right and responsibility to make informed decisions about their care in partnership with their health care providers. In order to facilitate informed choice women should be provided with information and support that is evidence based, culturally appropriate and tailored to their needs. The values, beliefs and individual needs of each woman and her family should be sought and the final decision about the care and treatment options chosen by the woman should be respected.
Identification
Copyright
Copyright © 2017 Published by Elsevier Inc. on behalf of The Society of Obstetricians and Gynaecologists of Canada/La Société des obstétriciens et gynécologues du Canada
