Prenatally diagnosed vasa previa: association with adverse obstetrical and neonatal outcomes

Fetoscopic Laser Ablation of Type II Vasa Previa: A Cost Benefit Analysis

OBJECTIVE

 We aimed to compare costs of two strategies for third-trimester type II vasa previa management: (1) fetoscopic laser ablation surgery (FLS) referral and (2) standard management (SM).

STUDY DESIGN

 A decision analytic model and cost-benefit analysis from a health care perspective were performed. The population included patients with type II vasa previa at approximately 32 weeks. SM entailed 32-week antepartum admission and cesarean at approximately 35 weeks. FLS referral included consultation and possible laser surgery at 32 weeks for willing/eligible candidates. Successful laser surgery allowed the possibility of term vaginal delivery. Outcomes included antepartum admission, preterm birth, cesarean, neonatal transfusion, and death. Sensitivity analyses were performed.

RESULTS

 In base case analysis, FLS referral was cost saving compared with SM (total cost per patient $65,717.10 vs. 71,628.16). FLS referrals yielded fewer antepartum admissions, cesareans, premature births, neonatal transfusions, and deaths. Eligible referred patients choosing FLS incurred a total cost of $41,702.46, a >40% decrease compared with SM. FLS referral was cost saving in all one-way sensitivity analyses except when antepartum admission costs were low. In threshold analyses, FLS referral was cost saving unless laser surgery cost was >$39,892 (2.75x expected cost), antepartum admission cost for monitoring of vasa previa or ruptured membranes was <$7,455, <11% patients were eligible for laser surgery, and when <12% of eligible patients chose laser surgery. In two-way sensitivity analysis, FLS referral was cost saving except at very high laser surgery costs and extremely low antepartum admission costs.

CONCLUSION

 Referral for FLS for type II vasa previa was cost saving and improved outcomes compared with SM, despite upfront costs, fetoscopy-related risks, and many patients being ineligible or not opting for surgery after referral.

KEY POINTS

· Vasa previa rupture may lead to fetal exsanguination and death.. · Late preterm cesarean is common practice for prenatally diagnosed vasa previa.. · Successful fetoscopic laser ablation for type II vasa previa has been described.. · Laser ablation of vasa previa allows for a safe-term vaginal delivery.. · Referral for laser surgery is cost saving and is associated with improved outcomes..

Vasa previa in singleton pregnancies: diagnosis and clinical management based on an international expert consensus

BACKGROUND

There are limited data to guide the diagnosis and management of vasa previa. Currently, what is known is largely based on case reports or series and cohort studies.

OBJECTIVE

This study aimed to systematically collect and classify expert opinions and achieve consensus on the diagnosis and clinical management of vasa previa using focus group discussions and a Delphi technique.

STUDY DESIGN

A 4-round focus group discussion and a 3-round Delphi survey of an international panel of experts on vasa previa were conducted. Experts were selected on the basis of their publication record on vasa previa. First, we convened a focus group discussion panel of 20 experts and agreed on which issues were unresolved in the diagnosis and management of vasa previa. A 3-round anonymous electronic survey was then sent to the full expert panel. Survey questions were presented on the diagnosis and management of vasa previa, which the experts were asked to rate on a 5-point Likert scale (from "strongly disagree"=1 to "strongly agree"=5). Consensus was defined as a median score of 5. Following responses to each round, any statements that had median scores of ≤3 were deemed to have had no consensus and were excluded. Statements with a median score of 4 were revised and re-presented to the experts in the next round. Consensus and nonconsensus statements were then aggregated.

RESULTS

A total of 68 international experts were invited to participate in the study, of which 57 participated. Experts were from 13 countries on 5 continents and have contributed to >80% of published cohort studies on vasa previa, as well as national and international society guidelines. Completion rates were 84%, 93%, and 91% for the first, second, and third rounds, respectively, and 71% completed all 3 rounds. The panel reached a consensus on 26 statements regarding the diagnosis and key points of management of vasa previa, including the following: (1) although there is no agreement on the distance between the fetal vessels and the cervical internal os to define vasa previa, the definition should not be limited to a 2-cm distance; (2) all pregnancies should be screened for vasa previa with routine examination for placental cord insertion and a color Doppler sweep of the region over the cervix at the second-trimester anatomy scan; (3) when a low-lying placenta or placenta previa is found in the second trimester, a transvaginal ultrasound with Doppler should be performed at approximately 32 weeks to rule out vasa previa; (4) outpatient management of asymptomatic patients without risk factors for preterm birth is reasonable; (5) asymptomatic patients with vasa previa should be delivered by scheduled cesarean delivery between 35 and 37 weeks of gestation; and (6) there was no agreement on routine hospitalization, avoidance of intercourse, or use of 3-dimensional ultrasound for diagnosis of vasa previa.

CONCLUSION

Through focus group discussion and a Delphi process, an international expert panel reached consensus on the definition, screening, clinical management, and timing of delivery in vasa previa, which could inform the development of new clinical guidelines.

Incidence and causes of perinatal death in prenatally diagnosed vasa previa: a systematic review and meta-analysis

OBJECTIVE

This study aimed to estimate the perinatal mortality associated with prenatally diagnosed vasa previa and to determine what proportion of those perinatal deaths are directly attributable to vasa previa.

DATA SOURCES

The following databases have been searched from January 1, 1987, to January 1, 2023: PubMed, Scopus, Web of Science, and Embase.

STUDY ELIGIBILITY CRITERIA

Our study included all studies (cohort studies and case series or reports) that had patients in which a prenatal diagnosis of vasa previa was made. Case series or reports were excluded from the meta-analysis. All cases in which prenatal diagnosis was not made were excluded from the study.

METHODS

The programming language software R (version 4.2.2) was used to conduct the meta-analysis. The data were logit transformed and pooled using the fixed effects model. The between-study heterogeneity was reported by I2. The publication bias was evaluated using a funnel plot and the Peters regression test. The Newcastle-Ottawa scale was used to assess the risk of bias.

RESULTS

Overall, 113 studies with a cumulative sample size of 1297 pregnant individuals were included. This study included 25 cohort studies with 1167 pregnancies and 88 case series or reports with 130 pregnancies. Moreover, 13 perinatal deaths occurred among these pregnancies, consisting of 2 stillbirths and 11 neonatal deaths. Among the cohort studies, the overall perinatal mortality was 0.94% (95% confidence interval, 0.52-1.70; I2=0.0%). The pooled perinatal mortality attributed to vasa previa was 0.51% (95% confidence interval, 0.23-1.14; I2=0.0%). Stillbirth and neonatal death were reported in 0.20% (95% confidence interval, 0.05-0.80; I2=0.0%) and 0.77% (95% confidence interval, 0.40-1.48; I2=0.0%) of pregnancies, respectively.

CONCLUSION

Perinatal death is uncommon after a prenatal diagnosis of vasa previa. Approximately half of the cases of perinatal mortality are not directly attributable to vasa previa. This information will help in guiding physicians in counseling and will provide reassurance to pregnant individuals with a prenatal diagnosis of vasa previa.

Third-trimester fetoscopic ablation therapy for types II and III vasa previa

BACKGROUND

Vasa previa is an obstetrical condition in which fetal vessels located near the cervix traverse the fetal membranes unprotected by underlying placenta. Type I vasa previa arises directly from a velamentous cord root, whereas types II and III arise from an accessory lobe or a distal lobe of the same placenta, respectively. Fetoscopic laser ablation for types II and III vasa previa is a novel therapeutic option with benefits that include surgical resolution of the vasa previa, avoidance of prolonged hospitalization, and opportunity for a term vaginal delivery. The potential risks of fetoscopy can be mitigated by delaying laser surgery until a gestational age of 31 to 33 weeks, immediately before anticipated hospitalized surveillance.

OBJECTIVE

This study aimed to assess feasibility and outcomes of types II and III vasa previa patients treated via fetoscopic laser ablation in the third trimester.

STUDY DESIGN

This is a retrospective study of singleton pregnancies with types II and III vasa previa treated with fetoscopic laser ablation at a gestational age ≥31 weeks at a single center between 2006 and 2022. Pregnancy and newborn outcomes were assessed. Continuous variables are expressed as mean±standard deviation.

RESULTS

Of 84 patients referred for vasa previa, 57 did not undergo laser ablation: 19 either had no or resolved vasa previa, 25 had type I vasa previa (laser-contraindicated), and 13 had type II or III vasa previa but declined laser treatment. Of the remaining 27 patients who underwent laser ablation, 7 were excluded (laser performed at <31 weeks and/or twins), leaving 20 study patients. The mean gestational age at fetoscopic laser ablation was 32.0±0.6 weeks, and total operative time was 62.1±19.6 minutes. There were no perioperative complications. All patients had successful occlusion of the vasa previa vessels (1 required a second procedure). All patients were subsequently managed as outpatients. The mean gestational age at delivery was 37.2±1.8 weeks, the mean birthweight was 2795±465 g, and 70% delivered vaginally. Neonatal intensive care unit admission occurred in 3 cases: 1 for respiratory distress syndrome and 2 for hyperbilirubinemia requiring phototherapy. There were no cases of neonatal transfusion, intraventricular hemorrhage, sepsis, patent ductus arteriosus, or death.

CONCLUSION

Laser ablation for types II and III vasa previa at 31 to 33 gestational weeks was technically achievable and resulted in favorable outcomes.

Vasa Previa

Vasa previa refers to unprotected fetal vessels running through the membranes over the cervix. Until recently, this condition was associated with an exceedingly high perinatal mortality rate attributable to fetal exsanguination when the membranes ruptured. However, ultrasonography has made it possible to diagnose the condition prenatally, allowing cesarean delivery before labor or rupture of the membranes. Several recent studies have indicated excellent outcomes with prenatally diagnosed vasa previa. However, outcomes continue to be dismal when vasa previa is undiagnosed before labor. Risk factors for vasa previa include second-trimester placenta previa and low-lying placentas, velamentous cord insertion, placentas with accessory lobes, in vitro fertilization, and multifetal gestations. Recognition of individuals who are at risk and screening them will greatly decrease the mortality rate from this condition. Because of the relative rarity of vasa previa, there are no randomized controlled trials to guide management. Therefore, recommendations on the diagnosis and management of vasa previa are based largely on cohort studies and expert opinion. This Clinical Expert Series review addresses the epidemiology, pathophysiology, natural history, diagnosis and management of vasa previa, as well as innovative treatments for the condition.

Perinatal Mortality Despite Prenatal Diagnosis of Vasa Previa: A Systematic Review

OBJECTIVE

To determine the causes and potential preventability of perinatal deaths in prenatally identified cases of vasa previa.

DATA SOURCES

Reports of prenatally identified cases of vasa previa published in the English language literature since 2000 were identified in Medline and ClinicalTrials.gov with the search terms "vasa previa," "abnormal cord insertion," "velamentous cord," "marginal cord," "bilobed placenta," and "succenturiate lobe."

METHODS OF STUDY SELECTION

All cases from the above search with an antenatally diagnosed vasa previa present at delivery in singleton or twin gestations with perinatal mortality information were included.

TABULATION, INTEGRATION, AND RESULTS

Cases meeting inclusion criteria were manually abstracted, and multiple antenatal, intrapartum, and outcome variables were recorded. Deaths and cases requiring neonatal transfusion were analyzed in relation to plurality, routine hospitalization, and cervical length monitoring. A total of 1,109 prenatally diagnosed cases (1,000 singletons, 109 twins) were identified with a perinatal mortality rate attributable to vasa previa of 1.1% (95% CI 0.6-1.9%). All perinatal deaths occurred with unscheduled deliveries. The perinatal mortality rate in twin pregnancies was markedly higher than that in singleton pregnancies (9.2% vs 0.2%, P <.001), accounting for 80% of overall mortality despite encompassing only 9.8% of births. Compared with individuals with singleton pregnancies, those with twin pregnancies are more likely to undergo unscheduled delivery (56.4% vs 35.1%, P =.01) despite delivering 2 weeks earlier (33.2 weeks vs 35.1 weeks, P =.006). An institutional policy of routine hospitalization is associated with a reduced need for neonatal transfusion (0.9% vs 6.0%, P <.001) and a reduction in the perinatal mortality rate in twin pregnancies (0% vs 25%, P =.002) but not in singleton pregnancies (0% vs 0.5%, P =.31).

CONCLUSION

Routine hospitalization and earlier delivery of twins may result in a reduction in the perinatal mortality rate. A smaller benefit from routine admission of individuals with singleton pregnancies cannot be excluded. There is currently insufficient evidence to recommend the routine use of cervical length measurements to guide clinical management.

Guideline No. 439: Diagnosis and Management of Vasa Previa

OBJECTIVE

To summarize the current evidence and to make recommendations for diagnosis and classification of vasa previa and for management of women with this diagnosis.

TARGET POPULATION

Pregnant women with vasa previa or low-lying fetal vessels.

OPTIONS

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.

OUTCOMES

Prolonged hospitalization, preterm birth, rate of cesarean delivery, and neonatal morbidity and mortality.

BENEFITS, HARMS, AND COSTS

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.

EVIDENCE

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.

VALIDATION METHODS

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).

INTENDED AUDIENCE

Obstetric care providers, including obstetricians, family physicians, nurses, midwives, maternal-fetal medicine specialists, and radiologists.

TWEETABLE ABSTRACT

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.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Directive clinique no 439: Diagnostic et prise en charge du vasa prævia

OBJECTIF

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.

POPULATION CIBLE

Femmes enceintes présentant un vasa prævia ou des vaisseaux ombilicaux péricervicaux.

OPTIONS

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. RéSULTATS: Hospitalisation prolongée, accouchement prématuré, césarienne et morbidité et mortalité néonatales. BéNéFICES, RISQUES ET COûTS: 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. DONNéES PROBANTES: 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. MéTHODES DE VALIDATION: 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). PROFESSIONNELS CONCERNéS: Fournisseurs de soins obstétricaux, y compris obstétriciens, médecins de famille, infirmières, sages-femmes, spécialistes en médecine fœto-maternelle et radiologistes. RéSUMé POUR TWITTER: 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.

Current Evidence on Vasa Previa without Velamentous Cord Insertion or Placental Morphological Anomalies (Type III Vasa Previa): Systematic Review and Meta-Analysis

Vasa previa carries a high risk of severe fetal morbidity and mortality due to fetal hemorrhage caused by damage to unprotected fetal cord vessels upon membrane rupture. Vasa previa is generally classified into types I and II. However, some cases are difficult to classify, and some studies have proposed a type III classification. This study aimed to review the current evidence on type III vasa previa. A systematic literature search was conducted, and 11 articles (2011-2022) were included. A systematic review showed that type III vasa previa accounts for 5.7% of vasa previa cases. Thirteen women with type III vasa previa were examined at a patient-level analysis. The median age was 35 (interquartile range [IQR] 31.5-38) years, and approximately 45% were assisted reproductive technology (ART) pregnancies. The median gestational week of delivery was 36 (IQR 34-37) weeks; the antenatal detection rate was 84.6%, and no cases reported neonatal death. The characteristics and obstetric outcomes (rate of ART, antenatal diagnosis, emergent cesarean delivery, gestational age at delivery, and neonatal mortality) were compared between types I and III vasa previa, and all outcomes of interest were similar. The current evidence on type III vasa previa is scanty, and further studies are warranted.

The Characteristics and Obstetric Outcomes of Type II Vasa Previa: Systematic Review and Meta-Analysis

Vasa previa is a rare fetal life-threatening obstetric disease classified into types I and II. This study aimed to examine the characteristics and obstetric outcomes of type II vasa previa. A systematic review was performed, and 20 studies (1998-2022) were identified. The results from six studies showed that type II vasa previa accounted for 21.3% of vasa previa cases. The characteristics and obstetric outcomes (rate of assisted reproductive technology (ART), antenatal diagnosis, emergent cesarean delivery, maternal transfusion, gestational age at delivery, and neonatal mortality) were compared between type I and II vasa previa, and all outcomes of interest were similar. The association between ART and abnormal placenta (bilobed placenta or succenturiate lobe) was examined in three studies, and the results were as follows: (i) increased rate of succenturiate lobes (ART versus non-ART pregnancy; OR (odds ratio) 6.97, 95% confidence interval (CI) 2.45-19.78); (ii) similar rate of abnormal placenta (cleavage-stage versus blastocyst embryo transfer); (iii) increased rate of abnormal placenta (frozen versus fresh embryo transfer; OR 2.97, 95%CI 1.10-7.96). Although the outcomes of type II vasa previa appear to be similar to those of type I vasa previa, the current evidence is insufficient for a robust conclusion.

Placental and Umbilical Cord Anomalies Diagnosed by Two- and Three-Dimensional Ultrasound

The aim of this review is to present a wide spectrum of placental and umbilical cord pathologies affecting the pregnancy. Placental and umbilical cord anomalies are highly associated with high-risk pregnancies and may jeopardize fetal well-being in utero as well as causing a predisposition towards poor perinatal outcome with increased fetal and neonatal mortality and morbidity. The permanent, computerized perinatology databases of different international centers have been searched and investigated to fulfil the aim of this manuscript. An extended gallery of prenatal imaging with autopsy correlation in specific cases will help to provide readers with a useful iconographic tool and will assist with the understanding and definition of this critical obstetrical and perinatological issue.

Timing of birth and adverse pregnancy outcomes in cases of prenatally diagnosed vasa previa: a systematic review and meta-analysis

OBJECTIVE

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.

DATA SOURCES

Ovid MEDLINE, PubMed, CINAHL, Embase, Scopus, and Web of Science were searched from inception to January 2022.

STUDY ELIGIBILITY CRITERIA

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.

METHODS

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.

RESULTS

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.

CONCLUSION

Prolonging pregnancies until 36 weeks' gestation seems to be safe and beneficial in otherwise uncomplicated pregnancies with antenatally diagnosed vasa previa.

Placental Types and Effective Perinatal Management of Vasa Previa: Lessons from 55 Cases in a Single Institution

BACKGROUND

We aimed to identify clinical characteristics and outcomes for each placental type of vasa previa (VP).

METHODS

Placental types of vasa previa were defined as follows: Type 1, vasa previa with velamentous cord insertion and non-type 1, vasa previa with a multilobed or succenturiate placenta and vasa previa with vessels branching out from the placental surface and returning to the placental cotyledons.

RESULTS

A total of 55 cases of vasa previa were included in this study, with 35 cases of type 1 and 20 cases of non-type 1. Vasa previa with type 1 showed a significantly higher association with assisted reproductive technology, compared with non-type 1 (p = 0.024, 60.0% and 25.0%, respectively). The diagnosis was significantly earlier in the type 1 group than in the non-Type 1 group (p = 0.027, 21.4 weeks and 28.6 weeks, respectively). Moreover, the Ward technique for anterior placentation to avoid injury of the placenta and/or fetal vessels was more frequently required in non-type 1 cases (p < 0.001, 60.0%, compared with 14.3% for type 1).

CONCLUSION

The concept of defining placental types of vasa previa will provide useful information for the screening of this serious complication, improve its clinical management and operative strategy, and achieve more preferable perinatal outcomes.