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

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

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

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

Prenatal diagnosis of a lean umbilical cord: A simple marker for the fetus at risk of being small for gestational age at birth

Objective. The purpose of this study was to investigate whether the prenatal diagnosis of a 'lean' umbilical cord in otherwise normal fetuses identifies fetuses at risk of being small for gestational age (SGA) at birth and of having distress in labor. The umbilical cord was defined as lean when its cross-sectional area on ultrasound examination was below the 10th centile for gestational age. Method. Pregnant women undergoing routine sonographic examination were included in the study. Inclusion criteria were gestational age greater than 20 weeks, intact membranes, and singleton gestation. The sonographic cross-sectional area of the umbilical cord was measured in a plane adjacent to the insertion into the fetal abdomen. Umbilical artery Doppler waveforms were recorded during fetal apnea and fetal anthropometric parameters were measured. Results. During the study period, 860 patients met the inclusion criteria, of whom 3.6% delivered a SGA infant. The proportion of SGA infants was higher among fetuses who had a lean umbilical cord on ultrasound examination than among those with a normal umbilical cord (11.5% vs. 2.6%, p < 0.05). Fetuses with a lean cord had a risk 4.4-fold higher of being SGA at birth than those with a normal umbilical cord. After 25 weeks of gestation, this risk was 12.4 times higher when the umbilical cord was lean than when it was of normal size. The proportion of fetuses with meconium-stained amniotic fluid at delivery was higher among fetuses with a lean cord than among those with a normal umbilical cord (14.6% vs. 3.1%, p < 0.001). The proportion of infants who had a 5-min Apgar score < 7 was higher among those who had a lean cord than among those with normal umbilical cord (5.2% vs. 1.3%, p < 0.05). Considering only patients admitted in labor with intact membranes and who delivered an appropriate-for-gestational-age infant, the proportion of fetuses who had oligohydramnios at the time of delivery was higher among those who had a lean cord than among those with a normal umbilical cord (17.6% versus 1.3%, p < 0.01). Conclusion. We conclude that fetuses with a lean umbilical cord have an increased risk of being small for gestational age at birth and of having signs of distress at the time of delivery

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

Balance between matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) in the cervical mucus plug estimated by determination of free non-complexed TIMP

<p>Abstract</p> <p>Background</p> <p>The cervical mucus plug (CMP) is a semi-solid structure with antibacterial properties positioned in the cervical canal during pregnancy. The CMP contains high concentrations of matrix metalloproteinase 8 and 9 (MMP-8, MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1). This indicates a potential to degrade extracellular matrix components depending on the balance between free non-complexed inhibitors and active enzymes.</p> <p>Methods</p> <p>Thirty-two CMPs collected during active labor at term were analyzed. Twelve CMPs were separated into a cellular and an extracellular/fluid phase and analyzed by gelatin and reverse zymography to reveal MMP and TIMP location. Twenty samples were homogenized, extracted and studied by the TIMP activity assay based on gelatin zymography. Enzyme-linked immunosorbent assay (ELISA) was used to determine TIMP-1, MMP-8 and MMP-9 protein concentrations, and gelatin and reverse zymography used to identify gelatinases and TIMPs, respectively. The Western blotting technique was applied for semi-quantification of alpha2-macroglobulin. An ELISA activity assay was used to detect MMP-8 and MMP-9 activity.</p> <p>Results</p> <p>ProMMP-2, proMMP-9, TIMP-1 and TIMP-2 were almost exclusively located in the fluid phase compared to the cellular phase of the CMP. All the extracted samples contained MMP-8, MMP-9, TIMP-1, TIMP-2 and alpha2-macroglobulin. Free non-complexed TIMP was detected in all the samples analyzed by the TIMP activity assay and was associated with TIMP-1 protein (R = 0.71, p < 0.001) and with the TIMP/MMP molar ratio (1.7 (1.1–2.5) (mean (95% confidence interval)) (R = 0.65, p = 0.002). The ELISA activity assay showed no activity from MMP-8 or MMP-9.</p> <p>Conclusion</p> <p>Due to their extracellular location, potential proteolytic activity from neutrophil-derived MMPs in the CMP could exert a biological impact on cervical dilatation and fetal membrane rupture at term. The functional TIMP activity assay, revealing excess non-complexed TIMP, and a molar inhibitor/enzyme ratio above unity, indicate that refined MMP control prevents CMP-originated proteolytic activity in the surrounding tissue.</p