Vasa Praevia: Diagnosis and Management

Diagnosis and Analysis of Vasa Previa Types With Flow HD Glass Body

OBJECTIVES

To explore the value of applying flow high definition (HD) glass body in prenatal diagnosis of vasa previa and to preliminarily discuss the types of vasa previa.

METHODS

Two-dimensional ultrasound, flow HD, and flow HD glass body were used to image the umbilical cord insertion site and placenta, observe the cervical internal os and surrounding areas, and retrospectively analyze cases of vasa previa.

RESULTS

There were 15 cases of vasa previa, including 14 cases of singleton pregnancies and 1 case of twin pregnancy, with a total of 22 vasa previa, including 10 veins and 12 arteries. There was 1 case with 3 vessels, 5 cases with 2 vessels, and 9 cases with a single vessel. Among them, in 3 cases of vasa previa detected at 12, 14, and 24 weeks, respectively, the vasa previa were relocated to a normal position at 24, 29, and 35 weeks of gestation when re-examined. Routine 2-dimensional ultrasound examination in this group showed tubular or circular hypoechoic areas near the cervical internal os, but vasa previa could not be confirmed. Flow HD could display color blood flow at and near the cervical internal os in 15 cases, but it was difficult to continuously show the course and source of the blood vessels under the chorion. Flow HD glass body from multiple angles could display the relationship between 15 cases of 22 vasa previa and the placenta and cervix. Combined with color Doppler blood flow spectra, flow HD glass body could determine the types of vasa previa.

CONCLUSIONS

Flow HD glass body imaging can clearly display vasa previa, showing their origin and the spatial relationship with the cervix and placenta in a 3-dimensional manner, displaying the course and attachment points of umbilical vessels under the chorion. It can observe the area of interest at any angle, and combined with color Doppler blood flow spectra, it can judge the vasa previa of the umbilical vein, providing a more definite imaging basis for clinical management.

The potential impact of universal screening for vasa previa in the prevention of stillbirths

OBJECTIVES

To estimate the number of pregnancies complicated by vasa previa annually in nine developed countries, and the potential preventable stillbirths associated with undiagnosed cases. We also assessed the potential impact of universal screening for vasa previa on reducing stillbirth rates.

METHODS

We utilized nationally-reported birth and stillbirth data from public databases in the United States, United Kingdom, Canada, Germany, Ireland, Greece, Sweden, Portugal, and Australia. Using the annual number of births and the number and rate of stillbirths in each country, and the published incidence of vasa previa and stillbirth rates associated with the condition, we estimated the expected annual number of cases of vasa previa, those that would result in a livebirth, and the potential preventable stillbirths with and without prenatal diagnosis.

RESULTS

There were 6,099,118 total annual births with 32,550 stillbirths, corresponding to a summary stillbirth rate of 5.34 per 1,000 pregnancies. The total expected vasa previa cases was estimated to be 5,007 (95 % CI: 3,208-7,201). The estimated number of livebirths would be 4,937 (95 % CI: 3,163-7,100) and 3,610 (95 % CI: 2,313-5,192) in pregnancies with and without a prenatal diagnosis of VP. This implies that prenatal diagnosis would potentially prevent 1,327 (95 % CI: 850-1,908) stillbirths in these countries, corresponding to a potential reduction in stillbirth rate by 4.72 % (95 % CI: 3.80-5.74) if routine screening for vasa previa was performed.

CONCLUSIONS

Our study highlights the importance of universal screening for vasa previa and suggests that prenatal diagnosis of prevention could potentially reduce 4-5 % of stillbirths.

Incidence and outcomes of vasa praevia in the United Kingdom

Background

Vasa praevia is an obstetric condition in which the fetal vessels run through the membrane over the internal cervical os, unprotected by the placenta or umbilical cord. It is associated with perinatal mortality if not diagnosed antenatally. We investigated the incidence and outcomes of vasa praevia in the UK.

Methods

We conducted a population-based descriptive study using the UK Obstetric Surveillance System (UKOSS). Cases were identified prospectively through monthly UKOSS submissions form all UK hospitals with obstetrician-led maternity units. All women diagnosed with vasa praevia who gave birth between 1 st December 2014 and 30 th November 2015 were included. The main outcome was incidence of vasa praevia with 95% confidence intervals, using 2015 maternities as the denominator.

Results

Fifty-one women met the case definition. The incidence of diagnosed vasa praevia was 6.64 per 100,000 maternities (95% CI 5.05-8.73). Of 198 units, 10 (5%) had a vasa praevia screening programme; one of these 10 units identified 25% of the antenatally diagnosed cases. Among women who had vasa praevia diagnosed or suspected antenatally (n=28, 55%), there were no perinatal deaths or hypoxic ischaemic encephalopathy (HIE). Twenty-four women with antenatal diagnosis were hospitalised at a median gestation of 32 weeks and caesarean section was scheduled at a median gestation of 36 weeks. When vasa praevia was diagnosed peripartum (n=23, 45%), the perinatal mortality rate was 37.5% and 47% of survivors developed HIE.

Conclusions

The incidence of diagnosed vasa praevia was lower than anticipated. There was high perinatal mortality and morbidity for cases not diagnosed antenatally. The incidence of antenatally identified cases was much higher in the few centres that actively screened for this condition, and the perinatal outcomes were better. However, this group were all delivered by caesarean section and may include women who would not have experienced any adverse perinatal outcome.

Fetoscopic laser photocoagulation: a medically reasonable treatment option in the management of types II and III vasa previa

Vasa previa is a condition where unprotected fetal vessels cross the cervix within the membranes, posing a considerable risk of fetal death or severe morbidity if the membranes rupture before or during delivery. There has not been a definitive in utero treatment for this condition. Patients are typically closely monitored and hospitalized in the early third trimester and scheduled for cesarean delivery before term. This approach poses considerable physical, social, psychological, and financial challenges for pregnant patients and their families. Furthermore, fetal vessel rupture may lead to severe hypoxic-ischemic injury and consequent neurodevelopmental impairment. Finally, babies delivered early due to vasa previa may face both the short- and long-term consequences of prematurity. Recently, fetoscopic laser photocoagulation using a single-port fetoscope has emerged as a potential therapeutic option for patients with types II and III vasa previa. This innovative approach aims to reduce hospital stays, increases the chance of successful vaginal delivery, and potentially allows pregnancies to reach full term, providing lifelong benefits for the infant. Preliminary clinical studies on human subjects have demonstrated promising results concerning the feasibility, safety, and efficacy of this intervention for a subset of patients with types II and III vasa previa. After reviewing the current state of the art, we argued that offering fetoscopic laser photocoagulation in specialized centers under IRB supervision meets the ethical obligations of beneficence and non-maleficence for both pregnant and fetal patients, as well as the autonomy-based obligations for pregnant patients.

Incorporation of vasa previa screening into a routine anomaly scan: A single center cohort study

INTRODUCTION

Vasa previa (VP), defined as unprotected fetal vessels traversing the membranes over the cervix, is associated with a high perinatal mortality when undiagnosed prenatally. Conversely, prenatal diagnosis with ultrasound and cesarean delivery before the membranes rupture is associated with excellent outcomes. However, controversy exists regarding screening for VP. In the UK, routine screening for VP is not recommended. The objective of this study was to report the incidence of VP and our experience in the detection of VP with a universal screening protocol at the time of the second-trimester fetal anomaly scan with third-trimester confirmation in an unselected population of pregnancies.

MATERIAL AND METHODS

We performed a single-center historical cohort study of all pregnant women who underwent routine second-trimester anomaly screening scans at West Middlesex University Hospital, London, UK, between 2012 and 2016. Over 5 years, every patient undergoing routine anomaly screening was evaluated for VP using a systematic protocol during their 20-week anomaly scan. Suspected cases of VP were rescanned in the third trimester by specialist sonographers with an interest in VP. The primary outcomes were the incidence and detection of VP.

RESULTS

During the study period, 24 690 anatomy scans were performed. A total of 64 patients were identified as having potential VP at the second-trimester anomaly screening scan, of which 19 were confirmed by the specialist sonographer in the third trimester and at delivery. The screen positive rate was 0.26% (95% confidence interval [CI] 0.20%-0.32%). VP at birth was found in 19/24690 births (1:1299 [95% CI: 1:832-1:2030] births). Universal screening for VP using our protocol had a sensitivity of 100% and a specificity of 99.78% (95% CI: 99.72%-99.84%). The false-positive rate of the second-trimester screen was 0.18% (95% CI: 0.13-0.24). There were no false positives or false negatives at delivery. Of the 19 patients with confirmed VP, 17 had scheduled cesarean deliveries, and two required emergency deliveries due to antepartum hemorrhage. One baby died, giving a perinatal mortality of 5%.

CONCLUSIONS

VP complicates approximately 1:1300 pregnancies. Routine screening for VP yielded a 100% detection rate. We suggest the inclusion of structured VP assessment in standard fetal anomaly screening programs.

Canadian Association of Radiologists Obstetrics and Gynecology Diagnostic Imaging Referral Guideline

The Canadian Association of Radiologists (CAR) Obstetrics and Gynecology Expert Panel consists of radiologists specializing in obstetrics and gynecology, obstetrics and gynecology physicians, a patient advisor, and an epidemiologist/guideline methodologist. After developing a list of 12 clinical/diagnostic scenarios, a systematic rapid scoping review was undertaken to identify systematically produced referral guidelines that provide recommendations for one or more of these clinical/diagnostic scenarios. Recommendations from 46 guidelines and contextualization criteria in the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) for guidelines framework were used to develop 68 recommendation statements across the 12 scenarios related to the evaluation of obstetrics and gynecology clinical and diagnostic scenarios. This guideline presents the methods of development and the imaging recommendations for a variety of obstetrical and gynecological conditions including pregnancy assessment, recurrent first trimester pregnancy loss, post-partum indications, disorders of menstruation, localization of intra-uterine contraceptive device, infertility assessment, assessment of adnexal mass, pelvic pain of presumed gynecological origin, and pelvic floor evaluation.

Prenatal Ultrasound Diagnosis of Vasa Previa With Careful Intraoperative Management: A Case Report

Vasa previa is a rare but potentially life-threatening condition to the fetus. Timely antenatal diagnosis and delivery by cesarean section (CS) can lead to a favorable outcome. Here, we report a case of recurrent pregnancy loss (G3A2) with vasa previa, which was diagnosed prenatally by ultrasound. She was admitted at her 31st week with bleeding per vaginum (PV) provisionally diagnosed as antepartum hemorrhage (APH) and managed conservatively as placenta previa. Follow-up ultrasonography (USG) revealed vasa previa at 33 weeks. The fetus was delivered by lower segment cesarean section (LSCS) after careful separation of the membranes and avoiding damage to the vessels as there was velamentous insertion of cord with the lower margin of the placenta in the lower segment. The baby was cared for in the neonatal intensive care unit due to prematurity and discharged after six days. This case report highlights the importance of prenatal ultrasound in diagnosing vasa previa and planning an elective cesarean section with caution intraoperatively for the safe delivery of the baby.

Prenatal diagnosis and postnatal outcome of Type-III vasa previa: systematic review of literature

OBJECTIVE

Type-III vasa previa (VP) is a rare form of VP, not necessarily associated with other placental or vascular anomalies, in which aberrant vessels run from the placenta to the amniotic membranes, near the internal cervical os, before returning to the placenta. Early diagnosis of Type-III VP is important but technically challenging. The objective of this study was to gather the current available evidence on the perinatal diagnosis and outcome of Type-III VP.

METHODS

A systematic review of the literature on the perinatal diagnosis of atypical Type-III VP was carried out in PubMed, MEDLINE and EMBASE accordingto PRISMA guidelines from inception to March 2023. Data extraction and tabulation were performed by two operators and checked by a third senior author. The quality of the included studies was evaluated using the National Institutes of Health tool for the quality assessment of case-series studies. Our local ultrasound database was searched for previously unreported recent cases. Characteristics of prenatally and postnatally diagnosed Type-III VP, including clinical features and perinatal outcomes, were summarized using descriptive statistics.

RESULTS

Eighteen cases of Type-III VP were included, of which 16 were diagnosed prenatally (14 cases were retrieved from 10 publications and two were unpublished cases from our center) and two were diagnosed postnatally (retrieved from two publications). All prenatal cases were diagnosed on transvaginal ultrasound at a mean gestational age of 29 weeks (median, 31 weeks; range, 19-38 weeks). Conception was achieved with in-vitro fertilization in 4/16 (25.0%) cases. There were no prenatal symptoms in 15/18 (83.3%) cases, while in two (11.1%) cases there was vaginal bleeding and in one (5.6%) preterm labor occurred. In 15/18 (83.3%) cases, at least one placental abnormality was observed, including low-lying insertion (9/17), succenturiate or accessory lobe (1/17), velamentous cord insertion (3/18) and marginal insertion (9/18). All prenatally diagnosed cases were liveborn and were delivered by Cesarean section before rupture of membranes at a median gestational age of 35 weeks (range, 32-38 weeks) without neonatal complications. Emergency Cesarean section was performed in 2/16 (12.5%) cases with a prenatal diagnosis and 1/2 (50.0%) cases with a postnatal diagnosis (P = 0.179). Among those with data available, an Apgar score of ≤ 7 was observed in the prenatally vs postnatally diagnosed group in 5/13 vs 1/1 cases, respectively, at the 1-min evaluation and 3/13 vs 1/1 cases, respectively, at the 5-min evaluation.

CONCLUSIONS

The prenatal diagnosis of Type-III VP is challenging, with few cases reported in the literature; however, it is crucial for minimizing the risk of adverse outcome by enabling early-term elective Cesarean delivery prior to rupture of membranes. Given that clinical manifestations and risk factors are non-specific, and that Type-III VP cannot be excluded when there is a normal cord insertion or a singular placental mass, systematic screening by transvaginal ultrasound in the general pregnant population is recommended, particularly in those with a low-lying or morphologically abnormal placenta and those who conceived using assisted reproductive technology. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Individualized management of vasa previa and neonatal outcomes

OBJECTIVE

To describe our individualized management protocol for women with an antenatal diagnosis of vasa previa (VP) and to report maternal and neonatal outcomes in patients managed according to our protocol.

METHODS

A retrospective study of prospectively collected data of antenatally diagnosed VP managed at our hospital between 2014 and 2021. Obstetric and neonatal outcomes were reviewed and analyzed.

RESULTS

Fourteen cases of antenatally diagnosed VP in 5150 total deliveries were analyzed (0.3%) Five cases (36%) of VP were diagnosed during the routine fetal morphological ultrasound screening, and nine cases (64%) were referred to our hospital due to perinatal complications. There were nine cases that required hospitalization (due to fetal growth restriction [FGR] [1], preterm labor [3], patients' request [5]). The other five were asymptomatic. Eight patients were delivered by scheduled cesarean section at around 36 weeks and only three neonates were admitted to NICU with transient tachypnea of newborn. However, six patients required CS before the scheduled dates because of other complications (preterm labor [3], abnormal cardiotocogram patterns [1], FGR [1] and twin pregnancy [1]). Four neonates born by CS before their scheduled dates were admitted to NICU. No cases required prolonged hospitalization and there were no serious neonatal complications.

CONCLUSION

Individualized management may lead to favorable outcomes with VP. Outpatient management may be considered in patients without risk factors. However, maternal hospitalization and earlier scheduled CS should be considered in symptomatic patients or those at risk for preterm delivery.

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.

In vitro Fertilization: An Alert for the Association of Placenta Previa and Vasa Previa - Ultrasound and Magnetic Resonance Imaging Findings

A 33-year-old woman, gravida 2 para 0, with a history of two previous miscarriages, underwent an investigation for recurrent miscarriage. After genetic counseling, the couple were submitted to the karyotype, which resulted in 45, X/46, XX mosaicism (mosaic Turner syndrome) in the wife result, while the husband chromosomal resulted in 46, XY (normal). After evaluating the options, the couple opted for in vitro fertilization. During prenatal follow-up, placenta and vasa previa were identified, considerably increasing the maternal-fetal mortality rate in this case. However, despite being a delicate and challenging case, the early diagnose was possible due to transvaginal ultrasound using color Doppler. Due to good care in obstetric follow-up, involving a multidisciplinary team, a therapeutic program and a successful outcome were possible. The patient underwent a cesarean section at 35 weeks of pregnancy, without complications, with a newborn in good general condition, despite the prematurity.

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.

Promoter methylation changes in the placenta involved in the relationship between prenatal depression and small for gestational age

BACKGROUND

Recent studies suggest that the incidence of small for gestational age (SGA) birth related to maternal depression, but the mechanism is unclear. The aim of this study was to explore the changes of promoter methylation in the placenta which may be involved in the relationship between prenatal depression and SGA.

METHODS

Three hundred forty-five pregnant women were enrolled in this prospective cohort study. Perinatal emotion and sleep quality in the second and third trimesters were assessed using self-rating depression scale, self-rating anxiety scale, and Pittsburgh sleep quality index. According to the exposure (depressed emotion of mother) and outcome (SGA), the placentas were divided into four groups. Methylation of the promoter regions of the placental CRH, HSD11β2, SLA16A10, DIO3, and MTNR1B genes was determined using next generation sequencing based on bisulfite sequencing PCR.

RESULTS

There were 97 (28.1%) and 95 (27.5%) pregnant women who had depression in the second trimester and third trimester, respectively. Thirty-five pregnant women had an SGA birth. The incidence of SGA births in this prospective cohort was 10.1%. The risk factors of SGA birth were low BMI of pregnancy women (RR = 0.71, 95%CI = 0.54 ~ 0.92), hypertensive disorder complicating pregnancy (HDCP, RR = 4.7, 95%CI = 1.18 ~ 18.72), and maternal depression in the second trimester (RR = 3.71, 95%CI = 1.31 ~ 12.16). We found that the CRH and HSD11β2 methylation levels were higher in the depression group than those in the non-depression group. Methylation levels of DIO3 were higher in SGA group than that in the non-SGA group. Higher methylation levels of CRH correlated with higher methylation levels of DIO3 in the placenta.

CONCLUSIONS

Maternal depression in the second trimester may lead to the changes of methylation levels in the promoter region of CRH and HSD11β2 gene, while the changes of methylation of DIO3 in subsequent could related to SGA. This study suggests that maternal depressed emotion during pregnancy may result in SGA due to the epigenetic changes of placenta.

Doppler evaluation of normal and abnormal placenta

Doppler techniques are needed for the evaluation of the intraplacental circulation and can be of great value in the diagnosis of placental anomalies. Highly sensitive Doppler techniques can differentiate between the maternal (spiral arteries) and fetal (intraplacental branches of the umbilical artery) components of the placental circulation and assist in the evaluation of the placental functional units. A reduced number of placental functional units can be associated with obstetric complications, such as fetal growth restriction. Doppler techniques can also provide information on decidual vessels and blood movement. Abnormal decidual circulation increases the risk of placenta accreta. Doppler evaluation of the placenta greatly contributes to the diagnosis and clinical management of placenta accreta, vasa previa, placental infarcts, placental infarction hematoma, maternal floor infarction, massive perivillous fibrin deposition and placental tumors. However, it has a limited role in the diagnosis and clinical management of placental abruption, placental hematomas, placental mesenchymal dysplasia and mapping of placental anastomoses in monochorionic twin pregnancies. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Benckiser's hemorrhage: about an uncommon case report

Background

Benckiser's hemorrhage is a serious obstetric emergency caused by rupture of one or more umbilical vessels of velamentous insertion, putting the fetus in distress and leading to rapid fetal death through exsanguination in utero. It is an uncommon condition associated with a neonatal mortality rate of 75–100%. This hemorrhage of fetal origin happens most often when the membranes rupture, whether spontaneously or artificially.

This is why prenatal diagnosis via ultrasound can only be beneficial and make it possible to schedule a prophylactic caesarean section before the onset of fetal death as well as other adverse perinatal outcomes.

Case presentation

We hereby present an uncommon case of a 27-year-old female patient, with no antenatal check-ups, who presented to the emergency department for labor-like pain at a gestational age of 32 weeks. On examination, blood pressure was 140/89mmhg. Shortly after her hospitalization, the patient was experiencing steady vaginal bleeding as well as spontaneous rupture of the membranes. Retroplacental hematoma was suspected. It was then quickly decided to do an emergency caesarean section. It was only at the examination of the placenta that the diagnosis was corrected with the visualization of torn velamentous vessels, allowing immediate resuscitation of the newborn and admission in neonatal intensive care unit for blood transfusions.

Conclusions

Detailed prenatal ultrasonography screening for vasa previa in high risk pregnancies prevent the onset of complications related to their rupture. An elective caesarean section should be carried out prior to the onset of labor, most often at 35 weeks of amenorrhea, avoiding rupture of membranes and fetal exsanguination, while taking into consideration the impact of iatrogenic prematurity.

•

Routine evaluation of the placental cord insertion site can identify pregnancies with velamentous insertion.

•

Prenatal diagnosis makes it possible to schedule a prophylactic cesarean section before the onset of fetal death through exsanguination in utero.

•

Diagnosis of Benckiser's hemorrhage allows to orientate towards an immediate neonatal management of hypovolemic shock state.

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.

Clinically Relevant Prenatal Ultrasound Diagnosis of Umbilical Cord Pathology

Umbilical cord abnormalities are not rare, and are often associated with structural or chromosomal abnormalities, fetal intrauterine growth restriction, and poor pregnancy outcomes; the latter can be a result of prematurity, placentation deficiency or, implicitly, an increased index of cesarean delivery due to the presence of fetal distress, higher admission to neonatal intensive care, and increased prenatal mortality rates. Even if the incidence of velamentous insertion, vasa praevia and umbilical knots is low, these pathologies increase the fetal morbidity and mortality prenatally and intrapartum. There is a vast heterogeneity among societies’ guidelines regarding the umbilical cord examination. We consider the mandatory introduction of placental cord insertion examination in the first and second trimester to practice guidelines for fetal ultrasound scans. Moreover, during the mid-trimester scan, we recommend a transvaginal ultrasound and color Doppler assessment of the internal cervical os for low-lying placentas, marginal or velamentous cord insertion, and the evaluation of umbilical cord entanglement between the insertion sites whenever it is incidentally found. Based on the pathological description and the neonatal outcome reported for each entity, we conclude our descriptive review by establishing a new, clinically relevant classification of these umbilical cord anomalies.

Vasa previa: when antenatal diagnosis can change fetal prognosis

OBJECTIVES

Evaluate ultrasound diagnostic accuracy, maternal-fetal characteristics and outcomes in case of vasa previa diagnosed antenatally, postnatally or with spontaneous resolution before delivery.

METHODS

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 2 cm 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 >2 cm from uterine internal os during scheduled ultrasound follow-ups in pregnancy.

RESULTS

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.

CONCLUSIONS

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.

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.

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.

[Cardiac arrest under special circumstances]

These guidelines of the European Resuscitation Council (ERC) Cardiac Arrest under Special Circumstances are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required for basic and advanced life support for the prevention and treatment of cardiac arrest under special circumstances; in particular, specific causes (hypoxia, trauma, anaphylaxis, sepsis, hypo-/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), specific settings (operating room, cardiac surgery, cardiac catheterization laboratory, dialysis unit, dental clinics, transportation [in-flight, cruise ships], sport, drowning, mass casualty incidents), and specific patient groups (asthma and chronic obstructive pulmonary disease, neurological disease, morbid obesity, pregnancy).

European Resuscitation Council Guidelines 2021: Cardiac arrest in special circumstances

These European Resuscitation Council (ERC) Cardiac Arrest in Special Circumstances guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required to basic and advanced life support for the prevention and treatment of cardiac arrest in special circumstances; specifically special causes (hypoxia, trauma, anaphylaxis, sepsis, hypo/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), special settings (operating room, cardiac surgery, catheter laboratory, dialysis unit, dental clinics, transportation (in-flight, cruise ships), sport, drowning, mass casualty incidents), and special patient groups (asthma and COPD, neurological disease, obesity, pregnancy).

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.

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.

Effect of types of placenta previa on maternal and neonatal outcomes: a 10-year retrospective cohort study

PURPOSE

Through this study, we aimed to evaluate the effects of different types of placenta previa (PP) on maternal and neonatal outcomes.

METHODS

This study was conducted in The Third Affiliated Hospital of Guangzhou Medical University and Tongji Hospital between January 2009 and 2019. PP was traditionally classified into four types, namely low-lying placenta, marginal, partial, and complete PP. Previous studies have classified PP into two types, namely low-lying placenta and PP. Based on our clinical experience, we proposed the classification of PP into three types, for the first time, which included low-lying placenta, "marpartial" (marginal and partial) PP, and complete PP. Multivariate logistic regression analysis was performed to determine the effects of different types of PP on maternal and neonatal outcomes.

RESULTS

In total, 4490 singleton pregnancies were complicated with PP. In the four-classification method, compared with women with low-lying placenta, women with complete PP had a risk of placenta accrete spectrum disorders, postpartum hemorrhage (PPH), hemorrhagic shock, severe PPH, blood transfusion, hysterectomy, puerperal infection, preterm labor, NICU admission, and low birth weight. There was no difference in maternal and neonatal outcomes between marginal and partial PP, except for increased chances of preterm labor and low birth weight in partial PP. In the two-classification method, PP was the risk factor for most of the adverse maternal and neonatal outcomes, compared with low-lying placenta.

CONCLUSION

Complete PP and low-lying placenta were associated with the highest and lowest risks of adverse pregnancy outcomes, respectively, whereas clinically similar outcomes were observed between marginal and partial PP. The three-classification of PP may be practical from the clinical perspective.

Antenatal diagnosis of vasa previa: report of three cases in an African setting

Vasa previa is characterised by unprotected umbilical vessels that are crossing the internal cervical os or lying close to it. When vasa previa is not detected during antenatal period, the perinatal outcome could be grievous. Ultrasound is the modality of choice in detection of vasa previa. Despite the increasing availability of ultrasound in modern times, its use in diagnosing vasa previa still remain very low in Africa. We present the sonographic findings and perinatal outcomes of three cases of vasa previa which were detected antenatally within a period of nine months in an African setting.

Fetoscopic Laser Ablation Therapy for Type II Vasa Previa

BACKGROUND

In type II vasa previa, fetoscopic laser ablation has the potential to avoid prolonged hospitalization, elective prematurity, and cesarean delivery associated with traditional conservative management.

OBJECTIVE

To assess the feasibility and to report perinatal outcomes of type II vasa previa patients treated via fetoscopic laser ablation.

STUDY DESIGN

This is a retrospective descriptive study of all women with vasa previa treated with laser at our center between 2006 and 2019. After 2010, laser ablation of vasa previa was only offered after 31 gestational weeks. Continuous variables are expressed as means ± SD.

RESULTS

33 patients were evaluated for laser ablation of suspected vasa previa. Fifteen were not candidates (7 had type I vasa previa and 8 had no vasa previa), and the 18 remaining had type II vasa previa. Ten (56%) elected to undergo in utero laser ablation of the vasa previa vessel(s), which was successful in all patients. The mean gestational age (GA) at the time of the procedure was 28.8 ± 5.4 weeks, and the total operative time was 48.1 ± 21.3 min; there were no perioperative complications. The number of vessels lasered were distributed as follows: 1 (2 cases), 2 (5 cases), and 3 (3 cases). All patients except for 1 were subsequently managed as outpatients. The mean GA at delivery was 35.5 ± 3.2 weeks, and vaginal delivery occurred in 5 cases. The 5 patients with singletons who underwent laser ablation for primary diagnosis of type II vasa previa after the protocol change in 2010 had the following outcomes: mean GA of surgery was 32.5 ± 0.8 weeks, mean GA at delivery was 38.1 ± 1.4 weeks, vaginal delivery occurred in all cases, mean birth weight was 2,965 ± 596 g, and none were admitted to the neonatal intensive care unit.

CONCLUSION

This cohort represents the largest number of vasa previa cases treated via in utero laser reported to date. Laser occlusion of type II vasa previa was technically achievable in all cases and resulted in favorable outcomes.

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.

Diagnosis and Management of Vasa Previa: A Comparison of 4 National Guidelines

Importance

Vasa previa represents an uncommon and life-threatening condition for the fetus. The prenatal identification of the condition may improve the outcome.

Objective

The aim of this study was to synthesize and compare published evidence of 4 national guidelines on diagnosis and management of vasa previa.

Evidence Acquisition

A descriptive review of 4 recently published national guidelines on vasa previa was conducted: Royal College of Obstetricians and Gynaecologists on "Vasa Praevia: Diagnosis and Management," Society for Maternal-Fetal Medicine on "Diagnosis and Management of Vasa Previa," Society of Obstetricians and Gynaecologists of Canada on "Guidelines for the Management of Vasa Previa," and the Royal Australian and New Zealand College of Obstetricians and Gynaecologists on "Vasa Praevia." These guidelines were compared regarding recommendations on diagnosis and management, while the quality of evidence was also reviewed based on each method of reporting.

Results

There were many similar recommendations in the compared guidelines regarding the diagnosis and management of vasa previa. Early prenatal diagnosis using ultrasound and color Doppler imaging, hospitalization or management as outpatients, and cesarean delivery in a tertiary center with experienced clinicians are the main recommendations.

Conclusions

Evidence-based guidelines may increase the awareness of the diagnosis and management of vasa previa among health care professionals and lead to more favorable perinatal outcomes.

Placental Implantation Disorders

Primary disorders of placental implantation have immediate consequences for the outcome of a pregnancy. These disorders have been known to clinical science for more than a century, but have been relatively rare. Recent epidemiologic obstetric data have indicated that the rise in their incidence over the last 2 decades has been iatrogenic in origin. In particular, the rising numbers of pregnancies resulting from in vitro fertilization (IVF) and the increased use of caesarean section for delivery have been associated with higher frequencies of previa implantation, accreta placentation, abnormal placental shapes, and velamentous cord insertion. These disorders often occur together.

Role of 2-Dimensional Ultrasound Imaging in Placental and Umbilical Cord Morphometry: Literature and Pictorial Review

Abnormalities of the placenta and umbilical cord have been associated with adverse pregnancy outcomes. Antenatal detection of placental and umbilical cord abnormalities using ultrasound (US) imaging is now gaining popularity with the advancements in obstetric US. This article reviews the use of 2-dimensional obstetric US as a tool to measure and assess placental and umbilical cord morphometry. It highlights the potential role of placental and umbilical cord morphometry as a valuable component of the screening tool for high risk pregnancies and identifies the need for further research to examine its feasibility.