Diagnosis Of Vasa Previa Research Articles

O38 - Identifying outcomes for vasa praevia that are important for women: a qualitative study to inform a Core Outcome Set

Many studies have demonstrated the key role of ultrasound for the antenatal diagnosis of vasa praevia to prevent perinatal death or severe perinatal morbidity via planned Caesarean birth. However, little is known currently about which outcomes really matter to women. A Core Outcome Set (COS) is the minimum group of outcomes that should be reported in studies on a specific topic so that the results can be compared and combined. Qualitative studies can identify more outcomes within this category, to generate a long list of outcomes to be administered and scored in the Delphi survey, and consensus phase of COS development. To explore the outcomes that are important for women with lived experiences of vasa praevia, to inform the development of a core outcome set, and gain a deeper understanding of why certain outcomes are more important than others in vasa praevia care. An international qualitative study was conducted with women using purposive sampling. Recruitment was facilitated by the International Vasa Previa Foundation. Semi-structured interviews were conducted over the phone, audio-recorded and transcribed verbatim. A descriptive interpretive data analysis was conducted taking inductive and deductive approaches. During August to December 2019, 18 women from USA, UK, Canada and Australia who received an antenatal (n=9) or postnatal (n=9) diagnosis of vasa previa were interviewed. Fifty-three outcomes were identified and described under five categories: baby’s survival and health (16 outcomes), mother’s physical health (12 outcomes), mother’s mental and emotional health (9 outcomes), delivery of care (9 outcomes), and resource use and cost (7 outcomes). This study identified a list of woman-centred outcomes, some of which are rarely measured in vasa praevia care. The findings from this study will inform the development of an optimal core outcome set for vasa praevia.

Clinical characteristics of a novel “Type 3” vasa previa: case series at a single center

Objective Vasa previa is a condition in which fetal blood vessels are located on fetal membranes within 2 cm of the internal cervical os. Vasa previa has been classified into two types: Type 1, in which vessels connect a velamentous umbilical cord to the placenta, and Type 2, in which vessels connect the lobes of a bilobed placenta or the placenta to a succenturiate lobe. However, there are also atypical cases that cannot be classified into these two types. These cases are manifested by a center or marginal cord insertion with a normal shaped placenta, and fetal vessels were also located on membranes around the internal cervical os. These cases were recently proposed as Type 3 vasa previa. The present study investigated the incidence of Type 3 vasa previa and elucidated differences in clinical and ultrasonographical characteristics between traditional types and Type 3. Methods This was a single-center observational study using a cohort of all vasa previa cases between January 2010 and April 2020. Results Among 8,723 deliveries, there were 14 cases (0.16%) of vasa previa, all of which were diagnosed prenatally by US, not after vaginal delivery or CS. There were 9 (64%), 0, and 5 (36%) cases of Types 1, 2, and 3, respectively. All 5 Type 3 cases had only one fetal aberrant vessel of vasa previa, while 6 out of 9 Type 1 cases (67%) had two or more aberrant vessels. Seven Type 1 cases (78%) possessed two or more known risk factors, such as velamentous cord insertion, whereas all Type 3 cases only had one. Difficulties were associated with diagnosing two out of the 14 cases of vasa previa using routine transvaginal ultrasonography (TVUS). In these cases, the aberrant fetal vessel of vasa previa was only one vein with a thin wall that was not clearly visualized by gray-scale TVUS as well as slow flow that was easily misread by color-Doppler. These cases were ultimately diagnosed as vasa previa based on non-pulsatile flow detected by color and pulsed Doppler. Conclusions The present results suggest that Type 3 may account for a large proportion of vasa previa cases. Most Type 3 cases may present with only one fetal aberrant vessel of vasa previa and fewer risk factors, suggesting that the diagnosis of vasa previa may be more challenging in Type 3 cases than in the other types. Vasa previa with a venous vasa previa needs to be considered because of the difficulties associated with an antenatal diagnosis due to unclear imaging of the vasculature or the lack of specific color Doppler flow patterns. Pulsed Doppler imaging may be helpful for the diagnosis of these cases.

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.

VP46.21: Prenatal diagnosis of vasa praevia in a district hospital over 20 years

VP46.21: Prenatal diagnosis of vasa praevia in a district hospital over 20 years

Ultrasound screening and management of vasa previa in Japan.

This study aimed to clarify ultrasound screening and management for vasa previa (VP) in perinatal centers and primary facilities in Japan. A questionnaire survey about antepartum ultrasound screening and management for VP was delivered in 2018. Questions were sent by email or post to perinatal centers and randomly selected primary hospitals or clinics throughout Japan. Seventy-seven perinatal centers and 300 primary facilities answered. VP was screened in 85.7% of perinatal centers and 81.3% of primary facilities. The reported incidence of VP was 0.05% (86/158 323) and 0.05% (28/54 791) in perinatal centers and primary facilities, respectively. When patients were diagnosed with VP, 88.7% of primary facilities referred the patient to a tertiary hospital. Routine hospitalization (100%) and steroid administration (46%) were frequently performed in perinatal centers. The median gestational age at planned cesarean section was significantly earlier in perinatal centers (34 weeks) than in primary facilities (37 weeks). Of the 31 reported cases of VP, 30 were reported as intact survival, but 1 case required an emergency cesarean section at 38 weeks of gestation without an antenatal diagnosis, resulting in neonatal death. More than 80% of obstetric facilities both perinatal centers and clinics in Japan perform ultrasound screening with for VP with similar detection rate. However, to further improve perinatal outcomes related to VP, pathophysiology and diagnosis of VP should be more widely recognized by obstetric caregivers throughout Japan.

Vasa previa: prenatal diagnosis and management.

Vasa previa is a rare disorder of placentation associated with a high rate of perinatal morbidity and mortality when undetected before delivery. We have evaluated the recent evidence for prenatal diagnosis and management of vasa previa. Around 85% of cases of vasa previa have one or more identifiable risk factors including in-vitro fertilization, multiple gestations, bilobed, succenturiate or low-lying placentas, and velamentous cord insertion. The development of standardized prenatal targeted scanning protocols may improve perinatal outcomes. There is no clear consensus on the optimal surveillance strategy including the need for hospitalization, timing of corticosteroids administration and the value of transvaginal cervical length measurements. Outpatient management is possible if there is no evidence of cervical shortening on ultrasound and there are no symptoms of bleeding or uterine contractions. Recent national guidelines and expert reviews have recommended scheduled cesarean section of all asymptomatic women presenting with vasa previa between 34 and 36 weeks' gestation. Prenatal diagnosis of vasa previa is pivotal to prevent intrapartum fetal death. Although there is insufficient evidence to support the universal mid-gestation ultrasound screening for vasa previa, recent evidence indicates the need for standardized prenatal targeted screening protocols of pregnancies at high-risk of vasa previa.

P21.09: Incorporation of vasa previa screening into a routine anomaly scan

Vasa previa (VP) has a reported fetal mortality of 60% if not recognised before attempt at vaginal delivery. Prenatal detection by ultrasound is possible in nearly all cases, but can be notoriously difficult unless there is a high index of suspicion. We report our experience in detection of VP using a structured protocol as part of the routine fetal anomaly scan at 20-22 weeks. Patients attending anomaly screening at a single centre over a 5 year period (2012-2016) underwent assessment for VP using a structured protocol as a part of a routine fetal anatomy scan. Suspected cases of VP were then re-scanned by a specialist sonographer and subsequently followed up. The diagnosis of VP was assigned by documentation of fetal vessels beneath the membranes, within 20 mm of the internal cervical os. 24690 anatomy scans were performed during the study period and 56 of these were identified as potential VP at the 20 -22 week anomaly scan. Of these, 20 were confirmed by the ultrasound specialist at 28 weeks or later. In five patients the only risk factor was a velamentous insertion. All 20 patients had planned Caesarean delivery but one patient bled at 35 weeks before planned delivery and this fetus died. Another patient experienced bleeding and an emergency Caesarean delivery at 31 weeks 3 days, and this baby lived. The remaining 18 had Caesarean delivery as planned. Placental histology was available in 11 cases. No case of VP was unexpectedly found at delivery during the study period (100% detection). The incidence of vasa previa in this unselected population is 1:1234. Use of a specific protocol as part of routine screening, permits high detection rate (100%), resulting in a low (5%) fetal mortality. We suggest that assessment for VP should be incorporated into routine fetal anatomy screening at 20-22 weeks using a structured protocol similar to one presented here.

Vasa Previa: Diagnosis and Management

(Am J Obstet Gynecol. 2016;215(2):223.e1–223.e6) Data from ultrasound scans and hospital records were examined for patients who gave birth from years 2000 to 2012. Patients with a diagnosis of vasa previa or a suspected vasa previa were considered for inclusion in the study. Only patients in whom the operative, delivery and/or pathology report specifically described a vasa previa met the criteria for a confirmed diagnosis. Among 68 pregnancies, 49 of them were confirmed to have vasa previa, either based on the operative report or the pathology report or both; 47 cases (96%) were diagnosed by antenatal ultrasound scanning, and 2 cases (4%) were documented at delivery. It was found that 86% of the cases had an identifiable placental and/or maternal risk factor. Women who were confirmed to have vasa previa delivered at a mean gestational age of 34.7 weeks. A total of 8 patients needed emergent cesarean delivery at a mean gestational age of 34.6 weeks, while the remaining 41 cases underwent planned cesarean delivery at a mean gestational age of 34.7 weeks. About 20% of the neonates (n=10) were found to have respiratory distress syndrome. However, there was no report of neonatal death or other major neonatal complications.

A Survey of Australasian Obstetric opinion regarding the antenatal diagnosis of Vasa Praevia

A Survey of Australasian Obstetric opinion regarding the antenatal diagnosis of Vasa Praevia

Prenatally Diagnosed Vasa Previa: A Single-Institution Series of 96 Cases

Prenatally Diagnosed Vasa Previa: A Single-Institution Series of 96 Cases

Descendent migration in vasa previa.

‘Placental migration’ involves the translocation of the placental site to the upper uterine segment in the second and third trimesters [1]. Since the uterine isthmus is usually closed during early pregnancy, subsequently opening with advancing gestation, this phenomenon is thought to strongly involve placental migration. Vasa previa is a condition in which the lower velamentous vessels are located over the region of the internal os. We hypothesized that the velamentous vessels in the lower uterine segment (low VCI) might migrate toward the uterine cervix, in opposition to the direction of migration of the placenta (descendent migration), as the amniotic bag expands toward the uterine cervix and opens the uterine isthmus, resulting in vasa previa. It was supposed that a diagnosis of vasa previa should be made after the opening of the uterine isthmus to ensure an accurate antenatal ultrasound diagnosis. To clarify our hypothesis, a prospective cohort study was conducted, in which the condition of the uterine cervix and isthmus and location of low VCIs were carefully observed using transvaginal ultrasound until delivery. The diagnosis of low VCI with vasa previa at 20 weeks of gestation was made in 12 patients (0.4 % of 2,923 total deliveries). Among eight cases of an opened uterine isthmus at 20 weeks of gestation, six cases of vasa previa and one case of low VCI without vasa previa were diagnosed. The findings in these cases were consistent until the time of delivery. The remaining case of placenta previa with low VCI at 20 weeks of gestation progressed to a low-lying placenta with vasa previa at delivery due to atrophy of the placenta around the internal os (Type II vasa previa). On the other hand, among the four patients with a closed uterine isthmus at 20 weeks of gestation, three were diagnosed with low VCI without vasa previa at delivery. However, in the remaining one case with a low VCI, migration of velamentous vessels toward the cervical os with opening of the isthmus resulting in vasa previa was observed during uterine contractions induced by a transvaginal ultrasound examination at 20 weeks of gestation. Figure 1 presents a transvaginal ultrasonographic picture of such descendent migration. Although velamentous vessels were not running on the uterine os before the opening of the uterine isthmus, the velamentous vessels on the amniotic membrane were descending toward the uterine isthmus with the expansion of the amniotic bag after the opening of the uterine isthmus was induced by uterine contractions. In conclusion, in contradiction to the concept of ascendant migration of the placenta, the velamentous vessels in the lower uterine segment occasionally migrated in the direction of the uterine cervix, resulting in vasa previa. However, the location of velamentous vessels was generally consistent until the time of delivery, after opening the uterine isthmus. This phenomenon suggests that the diagnosis of vasa previa should be made following the complete opening of the uterine isthmus. J. Hasegawa (&) H. Takita T. Arakaki A. Sekizawa Department of Obstetrics and Gynecology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8666, Japan e-mail: hasejun@oak.dti.ne.jp

OC14.04: A systematic review on the diagnostic accuracy of sonography in the diagnosis of vasa previa

<scp>OC</scp>14.04: A systematic review on the diagnostic accuracy of sonography in the diagnosis of vasa previa

Natural History of Vasa Previa Across Gestation Using a Screening Protocol

The purpose of this study was to estimate the prevalence and persistence rate of vasa previa in at-risk pregnancies using a standardized screening protocol. We conducted a descriptive study of patients with a diagnosis of vasa previa from a single ultrasound unit between June 2005 and June 2012. Vasa previa was defined as a fetal vessel within 2 cm of the internal cervical os on transvaginal sonography. Screening for vasa previa using transvaginal sonography with color flow mapping was performed routinely in the following situations: resolved placenta previa, prior pregnancy with vasa previa, velamentous insertion of the cord in the lower uterine segment, placenta succenturiata in the lower uterine segment, and twin gestations. A total of 27,573 patients were referred to our unit for fetal anatomic surveys over the study period. Thirty-one cases of vasa previa were identified, for an incidence of 1.1 per 1000 pregnancies. Twenty-nine cases had full records available for analysis. Five patients (17.2%) had migration and resolution of the vasa previa. When the diagnosis was made during the second trimester (<26 weeks), there was a 23.8% resolution rate (5 of 21); when the diagnosis was made in the third trimester, none resolved (0 of 8 cases). Of the 24 pregnancies (5 twin gestations and 19 singleton gestations) with persistent vasa previa, there was 100% perinatal survival and a median length of gestation of 35 weeks (range, 27 weeks 5 days-36 weeks 5 days). No known missed cases were identified over the study period. The use of standardized screening for vasa previa based on focused criteria was found to be effective in diagnosing vasa previa, with a 100% survival rate. Vasa previa diagnosed during the second trimester resolves in approximately 25% of cases.

Vasa Praevia: a descriptive review of existing literature and the evolving role of ultrasound in prenatal screening.

Introduction: Literature addressing the feasibility of prenatal detection of vasa praevia during the mid‐trimester morphology ultrasound scan is scarce, as is a lack of consensus about the appropriate management of pregnancies once it is detected. Method: The following descriptive review will provide historical context about the clinical significance, epidemiology, diagnosis and outcomes of pregnancies complicated by vasa praevia. It will also examine the role of ultrasound in the diagnosis of vasa praevia, and will examine current evidence surrounding this debate of whether routine screening for vasa praevia is possible, beneficial, or cost‐effective. Conclusion: Finally, it will highlight the need for increased research into effective management of pregnancies at high risk of, or affected by vasa praevia to reduce fetal mortality and maternal and fetal morbidity associated with the condition.

Placental vasa previa

In April, 2010, a 25-year-old woman at 33 weeks’ gestation in her fi rst pregnancy presented to us for examination of a previously identifi ed velamentous umbilical cord insertion into the placenta. Ultrasonography showed a fundal placenta, and the cord insertion site was not visible inserting into the placental surface. Transvaginal ultrasonography was performed because of our patient’s reports of vaginal spotting. Doppler ultrasonography showed fetal blood vessels coursing over the internal cervical os, consistent with a diagnosis of vasa previa (fi gure A). Uterine tocometry demonstrated frequent contractions. After administration of betamethasone for enhancement of fetal lung maturity, a caesarean section was done because of the risk of impingement or laceration of the vulnerable cord vasculature. She delivered a vigorous male neonate weighing 2115 g. Examination of the placenta was consistent with our diagnosis of a velamentous cord insertion site, with fetal blood vessels present over the cervix indicating vasa previa (fi gure B). At last follow-up in June, 2010, our patient and her infant were doing well.

P24.15: Early ultrasound diagnosis of vasa praevia and succenturiate placenta

P24.15: Early ultrasound diagnosis of vasa praevia and succenturiate placenta

Two cases of vasa previa diagnosed prenatally using three‐dimensional ultrasonography

We report two cases in which we describe the impact of sonography (US) in the management of vasa previa. In the first case, with two-dimensional US, the diagnosis of vasa previa was made at 21 weeks gestation. In the second case, using three-dimensional US, the diagnosis of vasa previa was made at 19 weeks gestation. An elective Cesarean section was carried out at 34 weeks in both cases. Diagnosis of vasa previa is critical when low-lying placenta or velamentous insertion of the umbilical cord is detected during the pregnancy.

Guidelines for the Management of Vasa Previa

ObjectivesTo 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. OutcomesReduction of perinatal mortality, short-term neonatal morbidity, long-term infant morbidity, and short-term and long-term maternal morbidity and mortality. EvidencePublished 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. ValuesThe 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 CostsThe benefit expected from this guideline is facilitation of optimal and uniform care for pregnancies complicated by vasa previa. SponsorsThe Society of Obstetricians and Gynaecologists of Canada. Summary StatementA 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) Recommendations1.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)

P04.18: Pitfalls in the sonographic diagnosis of vasa previa: confounding conditions and their implications

by conventional 2D ultrasound, it was confirmed by another senior sonographer. 3D color and power Doppler were applied to delineate vascular anatomy of this area subsequently. Confirmation of antenatal diagnosis was made in all newborns. Results: Four fetuses with PRUV were detected in these 1067 cases. The estimate incidence is about 0.375% (1 : 267). Ductus venosus were found in all of the fetuses. All of them had no other additional malformation. Discussion: The diagnosis of persistent right umbilical vein was easily made in a transverse section of the fetal abdomen with ultrasound findings of the portal vein towards to the stomach and fetal gallbladder located medially to the umbilical vein by twodimensional sonography. The incidence of PRUV in our patients was similar to other articles. Reconstruction of portal system in fetus with PRUV by 3-dimensional ultrasound was easy to delineate the vascular anatomy of this area. We proposed this modality can be used to help to understand the vascular anatomy of the fetus with PRUV.

Magnetic resonance imaging of vasa praevia

A 34 year old primigravid woman had an ultrasound examination at 20 weeks of gestation that showed a complete placenta praevia. Follow up transvaginal sonography at 24 weeks of gestation revealed echolucent linear structures overlying the cervix, suggesting a vasa praevia. The placenta appeared to have two lobes, with vessels running over the cervix between them. Pulsed Doppler demonstrated a fetal pulse rate of 140 beats per minute in these vessels. We decided to perform magnetic resonance imaging on the patient in order to determine whether vasa praevia could be diagnosed using magnetic resonance imaging, and also to see whether magnetic resonance imaging could add any further information beyond that which we already had with ultrasound and Doppler. We obtained approval from our Institutional Review Board to perform a magnetic resonance imaging on the patient for further evaluation of the vasa praevia. The patient was counselled, and informed consent was obtained. T2-weighted magnetic resonance imaging revealed three areas of signal void overlying the cervix (Fig. 1). Using two-dimensional time-of-flight sequences, flow was demonstrated through these structures. There was flow through two vessels in one direction (Fig. 2A), and flow through the third vessel in the opposite direction (Fig. 2B), consistent with the expected directions of flow in the umbilical arteries and the vein. The placenta was shown to have an accessory lobe, and these vessels ran between the lobes. The woman was hospitalised in the third trimester and was delivered by elective caesarean section at 351⁄2 weeks of gestation. The diagnosis of vasa praevia was confirmed at delivery; the placenta had two lobes, with communicating vessels running over the cervix between them. The live male infant had Apgar scores of 8 and 9, and was discharged home eight days later. The infant is doing well at 10 months of age.