Vasa previa: prenatal diagnosis and management

PURPOSE AND VIEW: 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. RECENT FINDINGS: 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. SUMMARY: 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

Prenatal diagnosis and management of vasa previa in twin pregnancies: a case series and systematic review

BACKGROUND: Twin pregnancies are at higher risks of velamentous cord insertion and vasa previa. In vitro fertilization is an additional risk factor of abnormal cord insertion and thus the incidence of vasa previa is likely to increase over the next decades. OBJECTIVE: We sought to evaluate the role of ultrasound imaging in optimizing the management of twins diagnosed with vasa previa antenatally. STUDY DESIGN: We searched our database for twin pregnancies diagnosed with vasa previa and managed antenatally using measurements of cervical length and performed a systematic review of articles that correlated prenatal diagnosis of vasa previa in twins and pregnancy outcome. PubMed and MEDLINE were searched for studies published from 1987 through October 20, 2016, using specific medical subject heading terms, key words, and their combination. The primary eligibility criteria were articles that correlated prenatal ultrasound imaging of vasa previa and pregnancy outcome in twins. The secondary eligibility criteria was the use of cervical length in the management of twin pregnancies diagnosed antenatally with vasa previa. Two authors independently assessed inclusion criteria, data extraction, and analysis. The final selection included 3 case report series, 9 retrospective cohort studies, and 1 retrospective case-control study of vasa previa diagnosed prenatally and confirmed at birth in twin pregnancies. RESULTS: The search of our databases identified 6 cases of dichorionic-diamniotic twins and 1 case of monochorionic-diamniotic twins diagnosed prenatally with vasa previa between 22-29 weeks and managed using cervical length. Two cases were delivered by emergency because of rapid changes in cervical length in one and bleeding on placenta previa in the other at 33 and 30 weeks, respectively. The systematic review identified data on 56 cases. The incidence of twin pregnancies diagnosed antenatally with vasa previa in the cohort and case-control studies was 11.0%. Data on chorionicity were available in only 34 cases and cervical length measurements were used by only the authors of 2 case reports and 4 cohort studies. Velamentous cord insertion was the most common additional ultrasound findings in twins presenting with vasa previa in both our series and the systematic review. CONCLUSION: Vasa previa is associated with specific prenatal and obstetric complications with different outcomes in singletons compared to twins. Data on the diagnosis and management of vasa previa in twin pregnancies are limited but there is enough evidence to warrant guidelines for targeted screening. To enable the development of efficient management protocols tailored to the need of individual cases, future studies of the screening, diagnosis, and management of vasa previa should be prospective and multicentric with detailed data on twins including chorionicity and use of cervical length

Prospective Evaluation of the Ultrasound Signs Proposed for the Description of Uterine Niche in Nonpregnant Women

OBJECTIVES: To evaluate the new ultrasound-based signs for the diagnosis of post-cesarean section uterine niche in nonpregnant women. METHODS: We investigated prospectively a cohort of 160 consecutive women with one previous term cesarean delivery (CD) between December 2019 and 2020. All women were separated into two subgroups according to different stages of labor at the time of their CD: subgroup A (n = 109; 68.1%) for elective CD and CD performed in latent labor at a cervical dilatation (≤4 cm) and subgroup B (n = 51; 31.9%); for CD performed during the active stage of labor (>4 cm). RESULTS: Overall, the incidence of a uterine niche was significantly (P  3 mm in subgroup A than in subgroup B and a significant negative relationship was found between the RMT and the cervical dilatation at CD (r = -0.22; P = .008). CONCLUSIONS: Sonographic cesarean section scar assessment indicates that the type of CD and the stage of labor at which the hysterotomy is performed have an impact on the location of the scar and the scarification process including the niche formation and RMT

Comparison between a prenatal sonographic scoring system and a clinical grading at delivery for Placenta Accreta Spectrum disorders

OBJECTIVE: Placenta Accreta Spectrum (PAS) disorders have become a major iatrogenic obstetric complication worldwide. Data on the accuracy of ultrasound examination diagnosis are limited by incomplete confirmation and variability in the description of the different grades of PAS at delivery. The aim of this study was to compare our prenatal routine sonographic screening and diagnostic scoring system with a standardized clinical grading system at birth in patient at risk of PAS. STUDY DESIGN: This is a retrospective cohort study of 607 pregnant patients with at least one prior cesarean delivery between December 2013 and December 2018. All patients were assessed for PAS using our institutional prenatal sonographic scoring system and the corresponding ultrasound findings were compared with those of a standardized clinical intra-operative macroscopic grading system of the degree of accreta placentation at vaginal birth or laparotomy. RESULTS: PAS was diagnosed clinically at birth in 50 (8.2%) cases, 17 of which were confirmed by histopathology. A low (score ≤ 5), medium (score 6-7), high (score ≥ 8) probability for PAS was reported in 502, 61 and 44 cases, respectively. The probability score increased significantly (p < .001) in women ≥2 prior cesarean deliveries, with an anterior low-lying/placenta previa, with absent clear space, increased in retroplacental vascularity and with the size and numbers of lacunae. The number of cases classified clinically as grade 1 (non-PAS) and 3 (adherent PAS) was significantly (p < .001) lower in women with a high probability score whereas the rates of the other grades was significantly (p < .001) higher. The widest discrepancy between ultrasound probability score and clinical grade was found for grade 2 which, describes a partial placental adherence and grades 4 and 5 which, refer to placental percreta which describes tissue having invade trough the uterine serosa and beyond. CONCLUSIONS: Both ends of the spectrum of accreta placentation remain difficult to diagnose antenatal and clinically at birth, in particular when no histopathologic confirmation is available. There is a need to develop ultrasound accuracy score systems that can differentiate between the different grades of PAS and which are validated by standardized clinical and pathology protocols

Second-trimester levels of fetoplacental hormones among women with placenta accreta spectrum disorders

Maternal serum human chorionic gonadotropin could be a useful biomarker in the prenatal diagnosis of placenta accreta spectrum disorders

Evaluation of the impact of vasa previa on feto-placental hormonal synthesis and fetal growth

Introduction A vasa previa (VP) refers to aberrant chorionic vessels which can either connect the chorionic plate to a velamentous cord (type I) or a succenturiate or accessory lobe to the main placental mass (type II). Methods We performed retrospective cohort study of 32 singleton pregnancies diagnosed with VP. The levels of maternal serum alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG) and unconjugated estriol (uE3) were measured at 15–18 weeks as part of the triple test screening for Trisomy 21. The data were subdivided according to the type of VP and compared with those of a control group with central cord insertion and no succenturiate or accessory placental lobe. Results Twenty one (65.6%) parturient women presented with VP type I and 11 (34.4%) with VP type II. The mean birthweight and placental weight was significantly higher in pregnancies with VP type II than in pregnancies with VP with VP type I (3037.3 ± 400.9 gr vs 2493.5 ± 491.6 gr; p = 0.004 and 511.0 ± 47.2 gr vs 367.1 ± 64.3 gr; p < 0.0001; respectively). The mean hCG level in VP type II was significantly (p < 0.001) higher than those with type I (2.38 MoM vs 1.17 MoM) and compared to controls (2.38 MoM vs 0.99 MoM). Conclusions There is no obvious impact on both placental and fetal growth in VP type II. By contrast, VP type I is associated with slower feto-placental growth secondary to impaired development and biological functions of the placenta during the first half of pregnancy

Impact of targeted scanning protocols on perinatal outcomes in pregnancies at risk of placenta accreta spectrum or vasa previa

Background Placenta accreta spectrum and vasa previa (VP) are congenital disorders of placentation associated with high morbidity and mortality for both mothers and newborns when undiagnosed before delivery. Prenatal diagnosis of these conditions is essential to allow multidisciplinary management and thus improve perinatal outcomes. Objective The objective of the study was to compare perinatal outcome in women with placenta accreta spectrum or vasa previa before and after implementation of targeted scanning protocols. Study Design This retrospective study included 2 nonconcurrent cohorts for each condition before and after implementation of the corresponding protocols (2004–1012 vs 2013–2016 for placenta accreta spectrum and 1988–2007 vs 2008–2016 for vasa previa). Clinical reports of women diagnosed with placenta accreta spectrum and vasa previa during the study periods were reviewed and outcomes were compared. Results In total, there were 97 cases of placenta accreta spectrum and 51 cases with vasa previa, all confirmed at delivery. In both cohorts, the prenatal detection rate increased after implementation of the scanning protocols (28 of 65 cases [43.1%] vs 31 of 32 cases [96.9%], P < .001, for placenta accreta spectrum and 9 of 18 cases [50%] vs 29 of 33 cases [87.9%], 87.9%, P < .01 for vasa previa). The perinatal outcome improved also significantly in both cohorts after implementation of the protocols. In the placenta accreta spectrum cohort, the estimated blood loss and the postoperative hospitalization stay decreased between periods (1520 ± 845 vs 1168 ± 707 mL, P < .01, and 10.9 ± 14.1 vs 5.7 ± 2.2 days, P < .05, respectively). In the vasa previa cohort, the number of 5 minute Apgar score ≤5 and umbilical cord pH <7 decreased between periods (5 of 18 cases [27.8%] vs 1 of 33 cases [3%]; P < .05, and 4 of 18 cases [22.2%] vs 1 of 33 cases [3%], P < .05, respectively). Conclusion The implementation of standardized prenatal targeted scanning protocols for pregnant women with risk factors for placenta accreta spectrum and vasa previa was associated with improved maternal and neonatal outcomes. The continuous increases in the rates of caesarean deliveries and use of assisted reproductive technology highlights the need to develop training programs and introduce targeted scanning protocols at the national and international levels

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

Background: There are limited data to guide the diagnosis and management of vasa previa. Currently, what is known is largely based on case reports or series and cohort studies. Objective: This study aimed to systematically collect and classify expert opinions and achieve consensus on the diagnosis and clinical management of vasa previa using focus group discussions and a Delphi technique. Study design: A 4-round focus group discussion and a 3-round Delphi survey of an international panel of experts on vasa previa were conducted. Experts were selected on the basis of their publication record on vasa previa. First, we convened a focus group discussion panel of 20 experts and agreed on which issues were unresolved in the diagnosis and management of vasa previa. A 3-round anonymous electronic survey was then sent to the full expert panel. Survey questions were presented on the diagnosis and management of vasa previa, which the experts were asked to rate on a 5-point Likert scale (from "strongly disagree"=1 to "strongly agree"=5). Consensus was defined as a median score of 5. Following responses to each round, any statements that had median scores of ≤3 were deemed to have had no consensus and were excluded. Statements with a median score of 4 were revised and re-presented to the experts in the next round. Consensus and nonconsensus statements were then aggregated. Results: A total of 68 international experts were invited to participate in the study, of which 57 participated. Experts were from 13 countries on 5 continents and have contributed to >80% of published cohort studies on vasa previa, as well as national and international society guidelines. Completion rates were 84%, 93%, and 91% for the first, second, and third rounds, respectively, and 71% completed all 3 rounds. The panel reached a consensus on 26 statements regarding the diagnosis and key points of management of vasa previa, including the following: (1) although there is no agreement on the distance between the fetal vessels and the cervical internal os to define vasa previa, the definition should not be limited to a 2-cm distance; (2) all pregnancies should be screened for vasa previa with routine examination for placental cord insertion and a color Doppler sweep of the region over the cervix at the second-trimester anatomy scan; (3) when a low-lying placenta or placenta previa is found in the second trimester, a transvaginal ultrasound with Doppler should be performed at approximately 32 weeks to rule out vasa previa; (4) outpatient management of asymptomatic patients without risk factors for preterm birth is reasonable; (5) asymptomatic patients with vasa previa should be delivered by scheduled cesarean delivery between 35 and 37 weeks of gestation; and (6) there was no agreement on routine hospitalization, avoidance of intercourse, or use of 3-dimensional ultrasound for diagnosis of vasa previa. Conclusion: Through focus group discussion and a Delphi process, an international expert panel reached consensus on the definition, screening, clinical management, and timing of delivery in vasa previa, which could inform the development of new clinical guidelines

A cost minimisation analysis of a telepaediatric otolaryngology service

Background: Paediatric ENT services in regional areas can be provided through telemedicine (tele-ENT) using videoconferencing or with a conventional outpatient department ENT service (OPD-ENT) in which patients travel to see the specialist. The objective of this study was to identify the least-cost approach to providing ENT services for paediatric outpatients

Calibration of a complex activated sludge model for the full-scale wastewater treatment plant

In this study, the results of the calibration of the complex activated sludge model implemented in BioWin software for the full-scale wastewater treatment plant are presented. Within the calibration of the model, sensitivity analysis of its parameters and the fractions of carbonaceous substrate were performed. In the steady-state and dynamic calibrations, a successful agreement between the measured and simulated values of the output variables was achieved. Sensitivity analysis revealed that upon the calculations of normalized sensitivity coefficient (Si,j) 17 (steady-state) or 19 (dynamic conditions) kinetic and stoichiometric parameters are sensitive. Most of them are associated with growth and decay of ordinary heterotrophic organisms and phosphorus accumulating organisms. The rankings of ten most sensitive parameters established on the basis of the calculations of the mean square sensitivity measure (δjmsqr) indicate that irrespective of the fact, whether the steady-state or dynamic calibration was performed, there is an agreement in the sensitivity of parameters