Vasa Previa Research Articles

The Diagnostic Accuracy of Transabdominal and Transvaginal Color Doppler Ultrasound for Pregnant Women with Vasa Previa and Velamentous Cord Insertion.

Objective The objective of this study is to evaluate feasibility and accuracy of transabdominal color Doppler ultrasound (TA-CDUS) and transvaginal color Doppler ultrasound (TV-CDUS) as screening methods for pregnant women with vasa previa (VP) and velamentous cord insertion (VCI). Methods A retrospective diagnostic accuracy study was performed on 5,434 pregnant women from 2018 to 2021, who underwent both TA-CDUS and TV-CDUS. Diagnostic performance of TA-CDUS and TV-CDUS was determined using specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and positive and negative likelihood ratios (LR+ and LR−), using the delivery information (gross examination) as the “Gold-standard”. Patient records were reviewed for demographics and diagnosis. Results The combination of VP and VCI was diagnosed in 37/5434 (0.68%) women at delivery. The sensitivity, specificity, PPV, NPV, and overall test accuracy of TA-CDUS were 72.97%, 99.85%, 77.14%, 99.81%, and 99.67%, respectively, for diagnosing VP with VCI. The corresponding values for TV-CDUS were 89.19%, 99.87%, 82.50%, 99.93%, and 99.80%, respectively. Moreover, the sensitivity of combination of TA-CDUS and TA-CDUS in determining VP with VCI was 97.30%, specificity 99.98%, PPV 97.30%, NPV 99.98%, and accuracy 99.96%. No significant difference in the misdiagnosis and missed diagnosis was found between the examination by TA-CDUS and TV-CDUS. Conclusions Both TA-CDUS and TV-CDUS can be acceptable diagnostic tools for assessment of pregnant women with VP and VCI, with a better application of TV-CDUS with higher accuracy. The combination of TA-CDUS and TV-CDUS could provide an objective imaging basis for choosing clinical treatment strategies and predicting prognosis.

Fetoscopic laser ablation of Type II Vasa Previa: a cost benefit analysis

Fetoscopic laser ablation surgery (FLS), a new treatment for vasa previa (VP), allows for full term vaginal delivery in some patients, but its upfront costs may be a barrier to more widespread use. We aimed to compare costs and outcomes of two strategies for third trimester management of Type II VP: (1) FLS referral and (2) standard management (SM).

Vasa previa in which velamentous cord insertion is combined with “boomerang vessels” that surround the placenta

Vasa previa in which velamentous cord insertion is combined with “boomerang vessels” that surround the placenta

Perinatal Outcome of Pregnancies With Prenatal Diagnosis of Vasa Previa: Systematic Review and Meta-analysis

(Abstracted from Ultrasound Obstet Gynecol 2021;57:710–719) Pregnancies with vasa previa are at risk for fetal death and hypovolemic shock due fetal blood loss. Several studies have shown that prenatal diagnosis of vasa previa improves the rate of live births.

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.

Vasa previa: when antenatal diagnosis can change fetal prognosis.

Evaluate ultrasound diagnostic accuracy, maternal-fetal characteristics and outcomes in case of vasa previa diagnosed antenatally, postnatally or with spontaneous resolution before delivery. Monocentric retrospective study enrolling women with antenatal or postnatal diagnosis of vasa previa at Sant'Anna Hospital in Turin from 2007 to 2018. Vasa previa were defined as fetal vessels that lay 2cm within the uterine internal os using 2D and Color Doppler transvaginal ultrasound. Diagnosis was confirmed at delivery and on histopathological exam. Vasa previa with spontaneous resolutions were defined as fetal vessels that migrate >2cm from uterine internal os during scheduled ultrasound follow-ups in pregnancy. We enrolled 29 patients (incidence of 0.03%). Ultrasound antenatally diagnosed 25 vasa previa (five had a spontaneous resolution) while four were diagnosed postnatally, with an overall sensitivity of 96.2%, specificity of 100%, positive predictive value of 96.2%, and negative predictive value of 100%. Early gestational age at diagnosis is significally associate with spontaneously resolution (p 0.023; aOR 1.63; 95% IC 1.18-2.89). Nearly 93% of our patient had a risk factor for vasa previa: placenta previa at second trimester or low-lying placenta, bilobated placenta, succenturiate cotyledon, velametous cord insertion or assisted reproduction technologies. Maternal and fetal outcomes in case of vasa previa antenatally diagnosed are significally improved. Our data support the evaluation of umbilical cord insertion during routine second trimester ultrasound and a targeted screening for vasa previa in women with risk factor: it allows identification of fetus at high risk, reducing fetal mortality in otherwise healthy newborns.

Vasa previa: Perinatal outcomes in singleton and multiple pregnancies.

Vasa previa (VP) is a rare and life-threatening condition for the fetus. It is associated with increased perinatal mortality rates. The current study sought to retrospectively analyze the perinatal outcomes of VP in singleton and multiple pregnancies between January 1, 2013 and December 31, 2019 at a tertiary hospital in west China. One hundred and fifty-seven cases of VP were identified, including 131 singletons, 23 twins and 3 triplets. VP in 20 cases was diagnosed at delivery. There were 183 live births. Neonatal mortality was significantly higher in cases with no prenatal diagnosis (9.7% vs. 1.3%, p = 0.035). There was a significantly higher rate of NICU admission, premature infant and neonatal pneumonia in cases with prenatal diagnosis (p < 0.05). Among twin pregnancies with VP as a prenatal diagnosis, there were significantly earlier gestational age at admission (31.1 vs. 34.1 weeks, p = 0.000) and delivery age (33.4 vs. 35.3 weeks, p = 0.000) than those among singleton pregnancies. The neonatal mortality in twins with prenatal diagnosis was significantly higher than that in singletons (0% vs. 6.9%, p = 0.037). Early hospitalization of VP in the third trimester may be reasonable. The data suggest that the timing of elective delivery at 34-36 weeks in singletons and 32-34 weeks in twins may be suitable. It should be emphasized to make corresponding optimal delivery time according to individual differences for the women, especially in twin pregnancy.

635 Neonatal morbidity associated with pregnancies complicated by vasa previa: a comparative study

Vasa previa (VP) affects 2.5 per 1000 deliveries. Neonatal complications of VP are thought to result from peripartum fetal hemorrhage from ruptured vessels and/or sequelae of iatrogenic prematurity, but there is scarce data on the post-natal course. This study aims to better characterize post-natal complications which may occur in pregnancies affected by VP. This is a retrospective cohort study of subjects with VP identified on ultrasound at a single tertiary care University center from 2011-2020. VP cohort was matched 2:1 with gestational-age-matched and birthweight-matched control group delivered after spontaneous preterm labor (SPB). Primary outcome was the difference in early neonatal morbidity between groups. Secondary outcomes included differences in neonatal intensive care unit (NICU) length of stay (LOS) and neonatal transfusion rates. Outcomes were evaluated with descriptive statistics, Mann-Whitney-U tests, and T-tests. There were 23 subjects (19 singleton, 3 dichorionic, 1 monochorionic twins) with VP and 46 singleton controls. Descriptive characteristics shown in Table 1. Completion of antenatal steroids (ANC) course was significantly more common in VP group (78.3% vs 42.9%, p<0.01). Neonatal transfusion rates were elevated in VP group (17.4% VP versus 4.7% SPB, p=0.08) and mean neonatal hematocrit was significantly lower (42.6% VP versus 47.5% SPB, p<0.01) (Table 1). Immediate assisted ventilation and prolonged assisted ventilation (>6hrs) were significantly higher in the VP cohort (Table 1). NICU LOS was significantly longer in neonates with VP (median 13 days (IQR 9-24) versus 5 days (IQR 0-13); p<0.01) and this persisted when stratified by gestational age (Figure 1). Neonates of pregnancies complicated by VP had significantly higher ventilatory requirements, despite higher rates of ANC completion. In addition, neonates had a longer NICU LOS implying more complex post-natal course. Neonatal transfusion rates were also 4 times higher in VP, but this did not reach statistical significance.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

713 Placental histopathology from pregnancies complicated by vasa previa

In vasa previa (VP), fetal vessels lay unprotected by Wharton’s Jelly while traversing the uterine cavity. The pathophysiologic effect of these unprotected and vulnerable vessels on placental development have not been well characterized. In the current study, the histopathological appearance of placentae from pregnancies complicated by VP are described. This is a retrospective cohort study of subjects with VP identified on ultrasound at a single tertiary University center from 2011-2020. Primary outcome was prevalence of placental histopathological lesions in VP. Secondary outcomes involved determination of prevalence of placental accreta spectrum (PAS) by both histopathology and clinically apparent PAS at delivery. Outcomes were evaluated with descriptive statistics & Fisher’s exact tests. 23 subjects (19 singleton, 3 dichorionic, 1 monochorionic twins) with VP were analyzed. Maternal vascular supply lesions were identified on placental histopathology in 73.9% of all cases and maternal inflammatory response in 34.8% (Table 1). Fetal vascular supply lesions and fetal inflammatory response were less common findings (13.0% and 17.4%, respectively) (Table 1). Histopathologic findings of PAS were present in 26.1% of cases. Histopathologic PAS was not more common in cases with prior uterine surgery as compared to without (50% versus 47.1%, p=1.0). Clinically apparent PAS at the time of delivery was only present in 1 case without prior uterine surgery. In the current study, placental histopathology of pregnancies complicated by VP showed surprisingly high rates of maternal vascular supply lesions and maternal inflammation. Unusually, despite exposed umbilical vessels, placentae did not demonstrate high rates of fetal vascular malperfusion lesions. Interestingly, histopathologic evidence of PAS was significantly higher in this cohort of VP, even those without prior uterine surgery, suggesting that VP may be an independent risk factor for PAS. Additional studies are needed to further investigate this finding.

931 Maternal and neonatal outcomes associated with vasa previa resolution during the antepartum period

In recent years, the phenomenon of “resolved” vasa previa has been increasingly described when vasa previa (VP) is detected on ultrasound in the midtrimester with a resolution rate as high as 20-26%. There is little information on the obstetrical outcomes associated with resolved VP. Our objective was to describe obstetrical and neonatal outcomes in women with resolved VP and compare them to women who have persistent VP. This was a multi-center descriptive and retrospective cohort study of patients diagnosed prenatally with VP on transvaginal ultrasound in the NYC MFM Research Consortium centers between 2012 and 2018. The primary outcome was gestational age (GA) at delivery. Other outcomes evaluated included mode of delivery, birthweight, NICU admission, and preterm birth. Data were analyzed using Mann-Whitney U test and Fisher exact test with p<0.05 defined as significance. 165 pregnancies with VP were included, of which 16 were twin gestations. 43 VP cases (26.1%) including one twin gestation were noted to resolve on subsequent ultrasound, of which 6 were lost to follow up. Pregnancies with resolved VP had a higher median GA at delivery, lower rate of preterm birth <37 weeks, and lower rate of cesarean delivery. There was no difference in rate of preterm birth <32 weeks (Table 1). Neonatal data was available on 131 newborns. In cases of resolved VP, neonates had a higher median birthweight and lower rate of NICU admission. There were no significant differences in rates of neonatal blood transfusion or neonatal death (Table 2). Resolved VP is associated with later GA at delivery, lower rate of cesarean delivery, and improved neonatal outcomes. However, it is not associated with a reduction in preterm birth prior to 32 weeks. The observed preterm birth rate in the resolved group of 16% raises concern that resolved VP may be a risk factor for preterm birth and merits further investigation. Once VP is diagnosed, surveillance for VP resolution should be performed as resolution has important implications for obstetrical and neonatal outcomes.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

321 Vaginal breech delivery: maternal and neonatal outcomes

Since the landmark Term Breech Trial (Hannah M et al, Lancet 2000) identified increased neonatal morbidity and mortality from vaginal breech delivery, it has declined substantially, as has provider experience. In light of this, we sought to evaluate severe maternal morbidity (SMM) and severe neonatal morbidity (SNM) and describe demographics among patients more recently undergoing singleton vaginal versus cesarean breech delivery. We conducted a retrospective population-based, cross-sectional analysis of linked birth certificate and neonatal and maternal discharge data produced by the California Maternal Quality Care Collaborative Data Center for the birth years 2007–2012 among term, singleton livebirths with breech presentation. Singleton deliveries with birthweight >2500g were included; those with birth defects, other fetal conditions, illicit drug use, and placenta and vasa previa were excluded. Multivariable logistic regression models were used to evaluate the mode of delivery, SMM, and SNM, adjusting for covariates selected a priori. Demographics and obstetric characteristics were determined by ICD-9 codes and examined by final mode of delivery. Among 3,164,928 livebirths, 1,634 vaginal breech deliveries and 67,140 cesarean breech deliveries met inclusion criteria. Vaginal breech delivery was associated with increased neonatal morbidity [adjusted OR (aOR) 1.95, 95% CI 1.45-2.62] without a significant difference in SMM (aOR 0.768, 95% CI 0.466 –1.27) (Table 1), and were more common among multiparous, Hispanic or non-Hispanic Black women, those with public insurance, lower BMI, and with few or no comorbidities (Table 2). Only 6.8% of vaginal breech deliveries were coded as “precipitous”. Compared to cesarean delivery, vaginal breech delivery was associated with a higher risk of SNM without differences in SMM. Socioeconomic disparities were noted among patients with the highest proportion of vaginal breech deliveries. A future study to identify the underlying reasons for these demographic differences is warranted.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

527 Is there an association between postoperative cervical length after cerclage and gestational age at delivery?

Ultrasound (US) surveillance of cervical length after US and physical exam (PE) indicated cerclage has been used to attempt to identify women at highest risk for spontaneous preterm birth (PTB). Data is limited regarding the change in cervical length (CL) after cerclage placement and timing of delivery. The objectives of this study were to determine if there is an association between change in CL (difference in CL measurement prior to and post cerclage placement) and gestational age (GA) at delivery in women undergoing US or PE indicated cerclage and if there is a cutoff in CL change predictive of delivery at term. This was a retrospective study of singleton pregnancies who underwent US or PE indicated cerclage between 7/2017 and 6/2019. Patients were excluded if there was history of prior PTB, multiple gestation, placenta or vasa previa, history indicated cerclage, known fetal chromosomal or structural abnormality, or incomplete records. The Spearman correlation coefficient was used to evaluate the relationship between the change in CL and GA at delivery and the change in CL and weeks gained in pregnancy. A ROC curve was generated to determine if there was a change in CL predictive of delivery at term. 43 patients met inclusion criteria. 77% (n=33) delivered at term and 23% (n=10) delivered preterm. There was no significant correlation between change in CL and GA at delivery (Spearman correlation coefficient = 0.16, p<0.32) or between change in CL and weeks gained in pregnancy (Spearman correlation coefficient = 0.05, p<0.76). A gain in CL of ≥1.4 cm after cerclage placement was associated with delivery at term (Figure 1). The change in CL after cerclage placement was not associated with GA at delivery or prolongation of pregnancy. The majority of patients who received US or PE indicated cerclage delivered at term. A gain in CL of ≥1.4 cm was associated with delivery at term. This information may be used to appropriately counsel patients undergoing US or PE indicated cerclage.

A velamentous and furcate cord insertion in a vasa previa setting: A rare but potentially life-threatening condition. Case report and review of the literature

A velamentous and furcate cord insertion in a vasa previa setting: A rare but potentially life-threatening condition. Case report and review of the literature

Clinical features of velamentous umbilical cord insertion and vasa previa: A retrospective analysis based on 501 cases.

To identify the risk factors associated with velamentous cord insertion (VCI) and investigate the association between adverse pregnancy outcomes and VCI in singleton pregnancies and those with vasa previa.A total of 59,976 single cases admitted from Qinhuangdao Maternal and Child Health Hospital and Qinhuangdao Beidaihe Hospital from January 2004 to January 2014 were included in this study. We retrospectively analyzed the perinatal complications, neonatal complications, and the clinical features, as well as the Color Doppler ultrasonography findings of the velamentous placenta and placenta previa.We reviewed the clinical data of 59,976 women with singleton pregnancies delivered in Qinhuangdao Maternal and Child Health Hospital and Qinhuangdao Beidaihe Hospital from January 2004 to January 2014. Risk factors and the risks of adverse pregnancy outcomes including admission to a neonatal unit, fetal death, preterm delivery, low birth weight of <2500 g, the infant being small for its gestation age, low Apgar scores (<7) at 1 and 5 minute were evaluated separately among women with and without VCI by means of logistic regression analyses.The prevalence of velamentous umbilical cord insertion was 0.84%, and the prevalence of vasa previa was 0.0017%. The independent risk factors for VCI were nulliparity, obesity, fertility problems, placenta previa, and maternal smoking. VCI was associated with a 1.83-, 2.58-, 3.62-, and 1.41-fold increase in the risk of retention in the neonatal unit, preterm delivery (<37 gestation weeks), low birth weight, and small-for-gestational age, compared to pregnancies involving normal cord insertion. Of the women with VCI, 16.1% underwent emergency cesarean section compared to 8.9% (P < .001) of women without VCI.The prevalence of VCI was 0.84% in singletons. The results suggest that VCI is a moderate risk condition resulted in increased risks of prematurity and impairment of fetal growth.

Vasa Previa: Review Article

The umbilical cord is the fetal lifeline and is the vital link between the fetus and placenta. Various abnormalities are observed in morphology and pathology of placenta. Variations in umbilical morphometry leads to neonatal morbidity and mortality. Vasa previa is one of the insertion anomaly of umbilical cord. Antenatal diagnosis is possible using ultrasonography. Diagnosis of vasa previa should be confirmed with colour or power doppler demonstrating pulsatile flow with fetal vascular waveform pattern. Vasa previa is one of the rare cause of antepartum haemorrhage. What differentiates vasa previa from other etiological factors of antepartum haemorrhage is that bleeding is of fetal origin. Although a rare anomaly, Vasa previa has significant mortality rates and therefore should always be looked for with great precision in antenatal ultrasonography.

Rethinking Prenatal Screening for Anomalies of Placental and Umbilical Cord Implantation.

The most common anomalies of implantation of the placenta and umbilical cord include placenta previa, placenta accreta spectrum, and vasa previa, and are associated with considerable perinatal and maternal morbidity and mortality. There is moderate quality evidence that prenatal diagnosis of these conditions improves perinatal outcomes and the performance of ultrasound imaging in diagnosing them is considered excellent. The epidemiology of placenta previa is well known, and it is standard clinical practice to assess placental location at the routine screening second-trimester detailed fetal anatomy ultrasound examination. In contrast, the prevalence of placenta accreta spectrum and vasa previa in the general population is more difficult to evaluate because detailed confirmatory histopathologic data are not available in most studies. The sensitivity and specificity of ultrasonography for the diagnosis of these anomalies is also difficult to assess. Recent epidemiologic studies show an increase in the incidence of placental and umbilical cord implantation anomalies, which may be the result of increased use of assisted reproductive technology and cesarean delivery. There is good evidence to support targeted standardized protocols for women at high risk and that screening and diagnosing placenta accreta spectrum and vasa previa should be integrated into obstetric ultrasound training programs.

Are we over-diagnosing vasa praevia? The experience and lessons learned in a tertiary centre.

Vasa praevia (VP) is a rare obstetric condition in which unprotected fetal vessels transverse the cervix, are vulnerable to rupture during labour and may result in rapid exsanguination of the fetus. Antenatal diagnosis of VP has resulted in excellent outcomes. However, there are little data available on the false positive rates for the antenatal diagnosis of VP. Improving accuracy of the diagnosis of VP can potentially improve outcomes and reduce unnecessary intervention. To assess our accuracy in the diagnosis of VP, examine our false positive diagnoses of VP and suggest strategies during antenatal ultrasound to aid in the antenatal diagnosis of VP. We conducted a retrospective descriptive study of women diagnosed with VP antenatally over 11years at a single tertiary hospital and eligible patients were identified from obstetric databases. All medical records, including ultrasound reports, were reviewed and compared with the placental histological findings and both operative and midwifery documentation of the cord insertion. Twenty-three women (25 babies) were diagnosed with VP and underwent a caesarean section delivery at a mean gestational age of 36weeks. The false positive rate in our series was 17% (4/23). Our study highlights the importance of postnatal confirmation of the diagnosis of VP and careful documentation of intraoperative findings of the placenta and cord insertion. We suggest strategies to aid in the accurate diagnosis of VP, thereby improving clinical decision-making and reducing unnecessary intervention.

Prevention of Stillbirth: Impact of Two-Stage Screening for Vasa Previa

OBJECTIVES To examine the feasibility and effectiveness of a two-stage ultrasound screening strategy for detection of vasa previa and to estimate the potential impact of screening on prevention of stillbirth. METHODS This was a retrospective study of data from prospective screening for vasa previa in singleton pregnancies, undertaken at the Fetal Medicine Unit at Medway Maritime Hospital, UK, between 2012 and 2018. Women booked for prenatal care and delivery in our hospital had routine ultrasound examinations at 11-13 and 20-22 weeks' gestation. Those with velamentous cord insertion at the inferior part of the placenta at the first-trimester scan and those with low-lying placenta at the second-trimester scan were classified as high-risk for vasa previa and had transvaginal sonography searching specifically for vasa previa, at the time of the 20-22-week scan. The management and outcome of cases with suspected vasa previa is described. We excluded cases of miscarriage or termination at < 24 weeks' gestation. RESULTS The study population of 26 830 singleton pregnancies included 21 (0.08%; 1 in 1278) with vasa previa. In all cases of vasa previa, the diagnosis was made at the 20-22-week scan and confirmed postnatally by gross and histological examination of the placenta. At the 11-13-week scan, cord insertion was classified as central in 25 071 (93.4%) cases, marginal in 1680 (6.3%), and velamentous in 79 (0.3%). In 16 (76.2%) of the 21 cases of vasa previa, cord insertion at the first-trimester scan was classified as velamentous at the inferior part of the placenta, in two cases (9.5%) as marginal and in three cases (14.3%) as central. The 21 cases of vasa previa were managed on an outpatient basis with serial scans for measurement of cervical length and elective Cesarean section at 34 weeks' gestation; all babies were liveborn but there was one neonatal death. In the study population, there were 83 stillbirths, none of which had evidence of vasa previa on postnatal examination. On the assumption that, if we had not diagnosed prenatally all 21 cases of vasa previa in our population, half of these cases would have resulted in stillbirth, then the potential impact of screening is prevention of 10.6% (10/94) of stillbirths. CONCLUSION A two-stage strategy of screening for vasa previa can be incorporated into routine clinical practice, and such a strategy could potentially reduce the rate of stillbirth. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

VP46.12: Vasa previa: how to improve diagnosis and management

VP46.12: Vasa previa: how to improve diagnosis and management

VP51.05: Screening transvaginal ultrasound for vasa previa: a retrospective cohort and economic analysis

VP51.05: Screening transvaginal ultrasound for vasa previa: a retrospective cohort and economic analysis