Vasa previa: prenatal diagnosis, natural evolution, and clinical outcome

doi:10.1016/S0029-7844(99)00600-6

Obstetrics & Gynecology

Volume 95, Issue 4, April 2000, Pages 572-576

https://doi.org/10.1016/S0029-7844(99)00600-6 Get rights and content

Abstract

Objective: To describe the prenatal ultrasonographic diagnosis, natural evolution, and clinical outcomes of vasa previa in a large population at a single institution.

Methods: We attempted to view the internal cervical os of 93,874 women with second- and third-trimester pregnancies during an 8–year period. Echogenic parallel or circular lines near the cervix, seen by gray-scale ultrasonography, raised the possibility of vasa previa. Diagnosis was confirmed by Doppler and endovaginal studies if aberrant vessels over the internal cervical os were suspected. Abnormal placental morphology and velamentous cord insertion were documented if they were identified during prenatal scans. Ultrasonographic findings were correlated with clinical courses, perinatal outcomes, and placental pathology examinations.

Results: Eighteen cases of vasa previa were suspected at a mean (± standard deviation) gestational age of 26.0 ± 6.3 weeks; the earliest diagnosis was at 15.6 weeks’ gestation. Eight of those cases initially showed placental edge over the internal os and later developed vasa previa after the placenta “receded” from the cervix. Six women had mild vaginal bleeding at a mean gestational age of 31.3 weeks. Three women had normal late third-trimester scans and were allowed to have uncomplicated vaginal deliveries. The remaining subjects delivered by cesarean. There were two deaths (one fetal and one neonatal), and minor preterm complications slightly prolonged infant hospitalizations. One set of preterm twins needed neonatal transfusions. Pathology findings included ten cases of velamentous insertion and three cases each of bilobed placentas, succenturiate lobes, and marginal cord insertion.

Conclusion: Vasa previa was detected in asymptomatic women as early as the second trimester. Perinatal outcome was generally favorable, although several infants had slightly extended newborn nursery admissions due to mild complications of prematurity.

Section snippets

Materials and methods

The Human Investigation Committee at William Beaumont Hospital approved this retrospective study. All gravidas with suspected vasa previa between January 1991 and December 1998, were identified by searching a customized computerized database of all scans done during that period. The imaging staff consisted of approximately seven registered ultrasonographers and four physicians (all obstetrician-gynecologists with additional subspecialty training in either radiology or maternal-fetal medicine).

Results

Our fetal ultrasound unit examined 93,874 women over 8 years. Eighteen women initially had vasa previa on gray-scale ultrasonography; three cases involved twin pregnancies. All 18 had evidence of aberrant vessels over the internal cervical os by gray-scale ultrasonography. Initial diagnoses were made at a mean (± standard deviation) gestational age of 26.0 ± 6.3 weeks, with 16 of 18 cases identified before 31 weeks. The earliest suspicion of vasa previa was in an asymptomatic woman at 15.6

Discussion

Vasa previa can be detected in some asymptomatic pregnant women as early as the second trimester. The first diagnostic clue might be echogenic linear or tubular structures seen near the internal cervical os during routine gray-scale ultrasonography (Figure 1). Such findings warrant more detailed examination by color or power Doppler ultrasonography. Endovaginal studies are not contraindicated because they do not cause or worsen vaginal bleeding in suspected cases. Unusual placental morphology,

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Cited by (157)

Vasa Previa: Outpatient management in low-risk asymptomatic patients is reasonable
2024, European Journal of Obstetrics and Gynecology and Reproductive Biology
Directive clinique n<sup>o</sup> 439 : Diagnostic et prise en charge du vasa prævia
2023, Journal of Obstetrics and Gynaecology Canada
Résumer les données probantes actuelles et énoncer des recommandations pour le diagnostic et la classification du vasa prævia et pour la prise en charge des femmes ayant reçu ce diagnostic.
Femmes enceintes présentant un vasa prævia ou des vaisseaux ombilicaux péricervicaux.
En cas de diagnostic soupçonné ou confirmé de vasa prævia ou de vaisseaux ombilicaux péricervicaux, prendre en charge la patiente à l’hôpital ou à domicile, puis pratiquer une césarienne avant terme ou à terme ou entreprendre une épreuve de travail.
Hospitalisation prolongée, accouchement prématuré, césarienne et morbidité et mortalité néonatales.
Les femmes ayant un vasa prævia ou des vaisseaux ombilicaux péricervicaux présentent un risque accru d’issues défavorables maternelles, fœtales ou postnatales, à savoir un diagnostic potentiellement erroné, un besoin d’hospitalisation, une restriction inutile des activités, un accouchement précoce et une césarienne inutile. L’optimisation des protocoles de diagnostic et de prise en charge peut améliorer les issues maternelles, fœtales et postnatales.
Des recherches ont été effectuées dans les bases de données Medline, PubMed, Embase et Cochrane Library, de leur création jusqu’à mars 2022, à partir de termes MeSH et de mots clés liés à la grossesse, au vasa prævia, aux vaisseaux prævia, à l’hémorragie ante partum, au col court, au travail prématuré et à la césarienne. Le présent document est un résumé des données probantes et non pas une revue méthodologique.
Les auteurs ont évalué la qualité des données probantes et la force des recommandations en utilisant le cadre méthodologique GRADE (Grading of Recommendations Assessment, Development and Evaluation). Voir l’annexe A en ligne (tableau A1 pour les définitions et tableau A2 pour l’interprétation des recommandations fortes et faibles).
Fournisseurs de soins obstétricaux, y compris obstétriciens, médecins de famille, infirmières, sages-femmes, spécialistes en médecine fœto-maternelle et radiologistes.
En cas de cordon et de vaisseaux ombilicaux non protégés dans les membranes près du col (vasa prævia y compris), une caractérisation échographique et une prise en charge avisée s’imposent pour réduire les risques pour le bébé et la mère pendant la grossesse et l’accouchement.
- 1.
  Un sinus marginal ou un segment de cordon au-dessus du col de l’utérus sont des causes fréquentes de diagnostic erroné de vasa prævia (faible).
- 2.
  Selon l’âge gestationnel auquel le vasa prævia ou les vaisseaux fœtaux bas sont diagnostiqués, le problème disparaît à l’approche du moment de l’accouchement chez une grande proportion de femmes (moyenne).
- 3.
  La plupart des femmes présentant un vasa prævia ont un facteur de risque associé (moyenne).
- 4.
  Selon les facteurs individuels de la patiente, la prise en charge du vasa prævia peut se faire en consultation externe en toute sécurité dans de nombreux cas (moyenne).
- 5.
  L’alitement et la réduction des activités n’améliorent pas les issues chez les femmes présentant un vasa prævia et peuvent même être néfastes. Cependant, les rapports sexuels et l’insertion d’un corps étranger dans le vagin ou le rectum sont des activités potentiellement risquées, en particulier au troisième trimestre (faible).
- 1.
  À l’interprétation des résultats de l’échographie obstétricale, on doit classifier les vaisseaux ombilicaux se trouvant à moins de 2 cm de l’orifice interne du col comme étant des vaisseaux prævia (forte, moyenne).
- 2.
  À l’interprétation des résultats de l’échographie obstétricale, on doit classifier les vaisseaux se trouvant à une distance de 2 à 5 cm de l’orifice interne du col comme étant des vaisseaux ombilicaux péricervicaux (conditionnelle, faible).
- 3.
  Pour diagnostiquer le vasa prævia ou d’autres variantes connexes, le fournisseur de soins doit utiliser l’échographie endovaginale avec codage couleur et Doppler pulsé (forte, moyenne).
- 4.
  Lorsqu’un diagnostic de vasa prævia ou de vaisseaux ombilicaux péricervicaux est posé bien avant l’accouchement, le fournisseur de soins obstétricaux doit reconfirmer le diagnostic près du moment de l’accouchement (forte, moyenne).
- 5.
  Le fournisseur de soins doit évaluer le site d’insertion du cordon chez toutes les femmes à l’échographie morphologique de routine au deuxième trimestre (conditionnelle, moyenne).
- 6.
  Le médecin qui interprète les résultats de l’échographie obstétricale ne doit pas diagnostiquer un vasa prævia ni une anomalie de la morphologie placentaire, de la localisation placentaire ou de l’insertion du cordon avant l’échographie de routine au deuxième trimestre (conditionnelle, moyenne).
- 7.
  Le dépistage ciblé du vasa prævia doit être effectué lors de l’échographie obstétricale chez toutes les femmes présentant un facteur de risque (forte, moyenne).
- 8.
  Le fournisseur de soins obstétricaux doit envisager l’hospitalisation à 32 semaines d’aménorrhée en cas de vasa prævia et avant 32 semaines d’aménorrhée chez les femmes présentant des facteurs de risque supplémentaires d’accouchement précoce, comme la grossesse multiple ou un col court (conditionnelle, moyenne).
- 9.
  En cas de vasa prævia et de grossesse monofœtale, la césarienne doit être réalisée entre 35 SA + 0 j et 35 SA + 6 j. Il faut toutefois envisager de devancer la césarienne en présence de facteurs de risque supplémentaires d’accouchement prématuré (forte, moyenne).
- 10.
  En cas de grossesse gémellaire compliquée par un vasa prævia, la césarienne doit être réalisée entre 33 SA + 0 j et 34 SA + 6 j pour la grossesse bichoriale et entre 32 SA + 0 j et 33 SA + 6 j pour la grossesse monochoriale. Il faut toutefois envisager de devancer la césarienne en présence de facteurs de risque supplémentaires d’accouchement prématuré, comme la grossesse multiple ou un col court (conditionnelle, faible).
- 11.
  En présence de vaisseaux ombilicaux péricervicaux, on doit envisager la césarienne entre 37 SA + 0 j et 38 SA + 6 j en cas de grossesse monofœtale et entre 36 SA + 0 j et 37 SA + 6 j en cas de grossesse gémellaire bichoriale (conditionnelle, faible).
- 12.
  En cas de vasa prævia, le fournisseur de soins obstétricaux doit prendre en compte l’accès rapide à une salle d’opération, à un obstétricien, à un anesthésiste et à une unité de soins intensifs néonataux appropriée dans le choix du lieu d’hospitalisation pour observation ou accouchement (conditionnelle, faible).
Guideline No. 439: Diagnosis and Management of Vasa Previa
2023, Journal of Obstetrics and Gynaecology Canada
To summarize the current evidence and to make recommendations for diagnosis and classification of vasa previa and for management of women with this diagnosis.
Pregnant women with vasa previa or low-lying fetal vessels.
To manage vasa previa in hospital or at home, and to perform a cesarean delivery preterm or at term, or to allow a trial of labour when a diagnosis of vasa previa or low-lying fetal vessels is suspected or confirmed.
Prolonged hospitalization, preterm birth, rate of cesarean delivery, and neonatal morbidity and mortality.
Women with vasa previa or low-lying fetal vessels are at an increased risk of maternal and fetal or postnatal adverse outcomes. These outcomes include a potentially incorrect diagnosis, need for hospitalization, unnecessary restriction of activities, an early delivery, and an unnecessary cesarean delivery. Optimization of diagnostic and management protocols can improve maternal and fetal or postnatal outcomes.
Medline, Pubmed, Embase, and the Cochrane Library were searched from inception to March 2022, using medical subject headings (MeSH) and keywords related to pregnancy, vasa previa, low-lying fetal vessels, antepartum hemorrhage, short cervix, preterm labour, and cesarean delivery. This document presents an abstraction of the evidence rather than a methodological review.
The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and weak recommendations).
Obstetric care providers, including obstetricians, family physicians, nurses, midwives, maternal-fetal medicine specialists, and radiologists.
Unprotected fetal vessels in placental membranes and cord that are close to the cervix, including vasa previa, need careful characterization by sonographic examination and evidence-based management to reduce risks to the baby and the mother during pregnancy and delivery.
- 1.
  A marginal sinus or a loop of cord above the cervix are frequent causes of an incorrect diagnosis of vasa previa (low).
- 2.
  Depending on gestational age when vasa previa or low-lying fetal vessels are diagnosed, these conditions will resolve closer to the time of delivery in a large proportion of women (moderate).
- 3.
  Most women with vasa previa have an associated risk factor (moderate).
- 4.
  Depending on individual patient factors, vasa previa can be safely managed on an outpatient basis in many women (moderate).
- 5.
  Bed rest or reduced activity does not improve outcomes in women with vasa previa and can be harmful. However, sexual intercourse/insertion of foreign bodies in vagina or rectum have potential for harm, particularly in the third trimester (low).
- 1.
  The physician interpreting an obstetric sonographic examination should classify fetal vessels <2 cm from the cervical os as vasa previa (strong, moderate).
- 2.
  The physician interpreting an obstetric sonographic examination should classify vessels between 2 and 5 cm from the cervical os as low-lying fetal vessels (conditional, low).
- 3.
  The obstetric sonographic provider should use transvaginal sonography with colour mapping and pulsed-wave Doppler to diagnose vasa previa or other related variants (strong, moderate).
- 4.
  When a diagnosis of vasa previa or low-lying fetal vessels is made remote from delivery, the obstetric care provider should confirm the diagnosis closer to the time of delivery (strong, moderate).
- 5.
  The obstetric sonographic provider should assess the placental cord insertion site in all women at the routine second trimester fetal anatomical scan (conditional, moderate).
- 6.
  The physician interpreting an obstetric sonographic examination should not diagnose an abnormality of placental morphology, location, placental cord insertion, or vasa previa before the routine second trimester obstetrical sonographic scan (conditional, moderate).
- 7.
  The obstetric sonographic provider should perform targeted screening for vasa previa in all women with a risk factor (strong, moderate).
- 8.
  The obstetric care provider should consider hospitalization in women with vasa previa at 32 weeks of gestation, and in women with additional risk factors for early delivery, such as multiple gestation or a short cervix, before 32 weeks (conditional, moderate).
- 9.
  In women with vasa previa and a singleton pregnancy, the obstetric care provider should perform a cesarean delivery at 35⁰ to 35⁶ weeks. They should consider an earlier delivery if there are additional risk factors for preterm delivery (strong, moderate).
- 10.
  In women with vasa previa and a twin pregnancy, the obstetric care provider should consider a cesarean delivery at 33⁰ to 34⁶ weeks for dichorionic twins and at 32⁰ to 33⁶ weeks for monochorionic twins. They should consider an earlier delivery if there are additional risk factors for preterm delivery, such as higher-order multiple pregnancy or a short cervix (conditional, low).
- 11.
  In women with low-lying fetal vessels, the obstetric care provider should consider a cesarean delivery at 37⁰ to 38⁶ weeks for a singleton pregnancy and at 36⁰ to 37⁶ weeks for dichorionic twins (conditional, low).
- 12.
  In women with vasa previa, the obstetric care provider should consider timely access to an operating room, an obstetrician, an anesthetist, and an appropriate neonatal intensive care unit when deciding location of admission for observation or delivery (conditional, low).
Timing of birth and adverse pregnancy outcomes in cases of prenatally diagnosed vasa previa: a systematic review and meta-analysis
2022, American Journal of Obstetrics and Gynecology
Citation Excerpt :
For this reason, it was difficult for the global assessments of conference abstracts to exceed fair. The most commonly reported outcomes included perinatal mortality,4,7,12–14,18,19,27–47,49–52 RDS requiring intubation,12,14,28,29,31,34–36,42,43,40,50 5-minute Apgar scores <7,1,2,12,14,18,19,27,28,45,31–37,39–44,46,47,49,50,51 requirement for blood transfusion by the neonate,4,7,12,14,19,31,34–37,39,40,42–44,47–49,51 NICU admission,4,7,14,19,27,32,34,35,37,39,40,42,43,45–47,49–52 and low birthweight.1,2,14,18–20,27,28,31,34,35,37,38,40,43,45–47,49–52 The number of cases of vasa previa in the included studies ranged from 2 to 586 with a mean of 63.7 and a median of 23.
The ideal time for birth in pregnancies diagnosed with vasa previa remains unclear. We conducted a systematic review aiming to identify the gestational age at delivery that best balances the risks for prematurity with that of pregnancy prolongation in cases with prenatally diagnosed vasa previa.
Ovid MEDLINE, PubMed, CINAHL, Embase, Scopus, and Web of Science were searched from inception to January 2022.
The intervention analyzed was delivery at various gestational ages in pregnancies prenatally diagnosed with vasa previa. Cohort studies, case series, and case reports were included in the qualitative synthesis. When summary figures could not be obtained directly from the studies for the quantitative synthesis, authors were contacted and asked to provide a breakdown of perinatal outcomes by gestational age at birth.
Study appraisal was completed using the National Institutes of Health quality assessment tool for the respective study types. Statistical analysis was performed using a random-effects meta-analysis of proportions.
The search identified 3435 studies of which 1264 were duplicates. After screening 2171 titles and abstracts, 140 studies proceeded to the full-text screen. A total of 37 studies were included for analysis, 14 of which were included in a quantitative synthesis. Among 490 neonates, there were 2 perinatal deaths (0.4%), both of which were neonatal deaths before 32 weeks’ gestation. In general, the rate of neonatal complications decreased steadily from <32 weeks’ gestation (4.6% rate of perinatal death, 91.2% respiratory distress, 11.4% 5-minute Apgar score <7, 23.3% neonatal blood transfusion, 100% neonatal intensive care unit admission, and 100% low birthweight) to 36 weeks’ gestation (0% perinatal death, 5.3% respiratory distress, 0% 5-minute Apgar score <7, 2.9% neonatal blood transfusion, 29.2% neonatal intensive care unit admission, and 30.9% low birthweight). Complications then increased slightly at 37 weeks’ gestation before decreasing again at 38 weeks’ gestation.
Prolonging pregnancies until 36 weeks’ gestation seems to be safe and beneficial in otherwise uncomplicated pregnancies with antenatally diagnosed vasa previa.
Variations in reported outcomes in studies on vasa previa: a systematic review
2020, American Journal of Obstetrics and Gynecology MFM
To evaluate reported outcomes of published studies on the diagnosis and management of vasa previa in pregnancy.
Databases such as MEDLINE, Embase, Cochrane, PubMed, and ClinicalTrials.gov were searched up to March 2018 for all published studies on vasa previa using combinations of the following medical subject headings and key words: vasa previa, placenta previa, low-lying placenta, succenturiate lobe or placenta, bilobed or bilobate placenta, and velamentous insertion. All original human research that described maternal, obstetric, placental, fetal or neonatal outcomes relating to pregnancies with vasa previa were included for analysis. Title and abstract screening and data extraction was conducted independently and in duplicate by 2 reviewers for all studies until total agreement for eligibility was achieved. Data extraction was also conducted in duplicate in approximately 50% of studies reviewed.
A total of 160 published studies (1004 pregnancies) were included. There was a wide range of reported outcomes, many of which were sparingly reported. The most commonly reported maternal outcomes included mode of delivery, presence of antepartum hemorrhage, time of diagnosis, and rupture of membranes. The presence of known risk factors for vasa previa such as a low-lying placenta, succenturiate or bilobed placenta, and (velamentous) cord insertion was incorrectly reported as “outcomes” in many studies. The most commonly reported fetal/neonatal outcomes included fetal heart rate, gestational age at delivery, birthweight, Apgar score, presence of neonatal anemia, cord blood gas measurements, need for blood transfusion, and death. Of note, only 3 studies reported outcomes related to life impact, maternal social and emotional functioning, perceived delivery of care, or resource utilization.
Despite the profound effect the diagnosis of vasa previa has on pregnant women, families, and healthcare systems, studies on vasa previa seldom report outcomes related to life impact and resource utilization. There is a need for the development of a core outcome set—a minimum standard set of outcomes deemed important by pregnant women and other stakeholders involved in their care—to standardize outcome reporting in future studies on vasa previa.
Frequency of spontaneous resolution of vasa previa with advancing gestational age
2019, American Journal of Obstetrics and Gynecology
Vasa previa is a serious obstetric complication that can result in fetal hemorrhage and death on spontaneous labor. Suggested management for vasa previa is elective hospitalization and cesarean delivery before spontaneous labor. There is little reported evidence of the rate of vasa previa resolution over the course of gestation. Identification of the resolution rate and of factors predictive of resolution potentially could improve clinical management and patient counseling.
The purpose of this study was to identify the resolution rate of vasa previa across gestation and to determine clinical and sonographic factors that are associated with vasa previa resolution.
We conducted a retrospective cohort study of all women who were diagnosed with vasa previa in a single ultrasound unit between 2005 and 2018. Vasa previa was defined as a fetal vessel within 2 cm of the internal cervical os on transvaginal sonography. The primary outcome was vasa previa resolution, defined as migration of the vasa previa to >2 cm away from the internal os.
One hundred women with vasa previa that had been diagnosed at a mean gestational age of 22.8±4.9 weeks were included. Thirty-nine women (39.0%; 95% confidence interval, 30–49%) had resolution of vasa previa at a mean gestational age of 28.6–4.7 weeks. Factors that were associated with vasa previa resolution were an earlier gestational age at diagnosis (adjusted odds ratio, 6.10; 95% confidence interval,1.92–19.40), vasa previa did not cover the internal os at diagnosis (adjusted odds ratio, 8.29; 95% confidence interval, 2.79–24.62), and vasa previa was not the result of a resolved placenta previa (adjusted odds ratio, 2.85; 95% confidence interval, 1.01-–8.03). One woman with a dichorionic twin pregnancy and vasa previa resolution (at 31 weeks gestation; fetal vessels located 2.8 cm from the internal os) presented at 33 weeks with massive bleeding and fetal death of twin A. It was unclear whether the death was related to vasa previa or placental abruption.
Thirty-nine percent of vasa previas in our population resolved over the course of pregnancy. Earlier gestational age at diagnosis, vasa previa not covering the internal os, and not having a resolved placenta previa all are associated independently with an increased likelihood of vasa previa resolution. Women with vasa previa should be observed serially to assess for vasa previa resolution, because many will resolve in the third trimester.

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Original ArticlesVasa previa: prenatal diagnosis, natural evolution, and clinical outcome

Abstract

Section snippets

Materials and methods

Results

Discussion

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Original Articles
Vasa previa: prenatal diagnosis, natural evolution, and clinical outcome