Vasa Previa and the Role of Fetal Fibronectin and Cervical Length Surveillance: A Review.

Vasa previa is a pregnancy complication that occurs when unprotected fetal blood vessels traverse the cervical os, placing the fetus at high risk of exsanguination and fetal death. These fetal vessels may be compromised by fetal movement and compression, leading to poor oxygen distribution and asphyxiation. Diagnostic tools for vasa previa management and preterm labor (PTL) include transvaginal ultrasound, cervical length (CL) surveillance and use of fetal fibronectin (FFN) testing. These tools can prove to be quite useful as they allow for lead time in the prediction of PTL and spontaneous rupture of membranes which can result in devastating outcomes for pregnancies affected by vasa previa. We conducted a literature review on vasa previa management and the usefulness of FFN and CL surveillance in predicting PTL and found 36 related papers. Although there is limited research available to show the impact of FFN and CL surveillance in the management of vasa previa, there is sufficient evidence to support FFN and CL surveillance in predicting the onset of PTL, which can have devastating consequences for the pregnancies affected. It can be extrapolated that these tools, by helping to determine pregnancies at risk for PTL, could improve management and outcomes in patients with vasa previa. Future studies investigating the management of vasa previa with FFN and CL surveillance to reduce the burden of PTL and its associated comorbidities are warranted.

Pulsatile vessel at the posterior bladder wall: A new sonographic marker for placenta percreta.

OBJECTIVE: We investigated using "pulsatile vessels at the posterior bladder wall" as a novel sonographic marker to demonstrate the severity of placenta accreta spectrum (PAS). METHODS: This observational case-control study of 30 pregnant women was performed at Hackensack Meridian Health's Center for Abnormal Placentation in 2020. The case group was made up of women with historically described sonographic signs of PAS and was compared against two control groups: (1) women with uncomplicated placenta previa and (2) women with no evidence of placenta previa sonographically. All patients were evaluated with Color Flow Doppler ultrasound to assess the presence of arterial vessels at the posterior bladder wall. The flow characteristics and resistance indices (RI) were noted in the presence of pulsatile vessels. All patients' placentation was clinically confirmed at delivery. Patients with clinical invasive placentation underwent histopathological diagnosis to confirm disease presence. RESULTS: Hundred percent of subjects in our series with suspected PAS exhibited pulsatile arterial vessels at the posterior bladder wall sonographically with a low RI of 0.38 ± 0.1 at an average of 24.6 ± 5.2 gestational weeks. Cases were histopathologically confirmed to have placenta percreta after delivery. Patients in either of the control groups did not display pulsatile vessels at the posterior bladder wall during antenatal sonographic evaluations and had no clinical evidence of PAS. CONCLUSION: The presence of posterior urinary bladder wall pulsatile arterial vessels with low RI, in addition to traditional sonographic markers increases the suspicion of severe PAS. Thus, these findings allow for the greater opportunity for coordination of patient care prior to delivery.

Preoperative cystoscopy could determine the severity of placenta accreta spectrum disorders: An observational study.

AIM: In the surgical treatment of placenta accreta spectrum disorders, cystoscopy for prophylactic stent placement is performed to protect the ureters from potential injury. Despite its frequent use, the use of cystoscopy in assessing the severity of these disorders has not been explored. Our objective was to find out if the abnormal findings documented during cystoscopy are associated with disease severity. METHODS: In this retrospective, observational cohort study (n = 56), the bladder wall was evaluated at the time of ureteral stent placement via cystoscopy in prenatally diagnosed placenta accreta spectrum cases. Three abnormal findings were commonly present in these cases: bulging of the posterior bladder wall, neovascularization and arterial pulsatility in the area of neovascularization. These findings were stratified according to severity in histologically confirmed specimens. Continuous variables were compared via two-tailed t-tests and Wilcoxon rank sum tests. Categorical data were evaluated using logistic regression analysis. RESULTS: Neovascularization affected 84%, bulging 71% and pulsatility 54% of the cases. Bulging and neovascularization increased with disease severity. Pulsatility occurred exclusively in percretas. Bulging was associated with a 12-fold (OR = 11.6, 95% CI 2.94-46.33, P = 0.0005) increased likelihood of percreta and neovascularization with a 17-fold (OR = 17.06, 95% CI 2.98-97.79, P = 0.0014) increase. Neovascularization and/or the presence of bulging of the bladder have high positive predictive value for placenta increta and percreta (91.5% and 95.0%, respectively). Cystoscopy can be used to assess the severity of placenta accreta spectrum cases preoperatively, especially when placentation is over the previous uterine scar and is in proximity to the bladder wall.

Interpregnancy interval and abnormally invasive placentation.

INTRODUCTION: The presence of a previous uterine scar is a strong risk factor for developing abnormally invasive placentation (AIP). We sought to determine whether a short interpregnancy interval predisposes to AIP. We hypothesized that a short interpregnancy interval after a previous cesarean delivery increases the risk of AIP in comparison with a longer interpregnancy interval. MATERIAL AND METHODS: We performed a retrospective cohort study of women with a histological diagnosis of AIP and a history of a previous cesarean section. Women were included in the control group if they had a previous cesarean section with a placenta underlying the previous uterine scar or an anterior previa. The time interval between pregnancy and AIP data was analyzed using the chi-square test and two-tailed Fisher's exact test. RESULTS: There was no statistical difference in the interpregnancy interval between women who had AIP vs the control group. Gravidity and parity were found to be significantly higher in the women with AIP vs the controls. CONCLUSIONS: These results suggest that a short interpregnancy interval may not increase the risk of developing AIP.

Prophylactic Hypogastric Artery Ligation during Placenta Percreta Surgery: A Retrospective Cohort Study.

Objective To evaluate if prophylactic hypogastric artery ligation (HAL) decreases surgical blood loss and blood products transfused. Study Design This is a retrospective cohort study comparing patients with placenta percreta undergoing prophylactic HAL at the time of cesarean hysterectomy versus those who did not. Data were presented as means ± standard deviations, proportions, or medians with interquartile ranges. Demographic and clinical data were compared in the groups using Student's t -test for normally distributed data or the Mann-Whitney U test for nonnormally distributed data. Fisher's exact test was used for proportions and categorical variables. Data are reported as significant where p was <0.05. Results There were 26 patients included in the control group with no HAL and 11 patients included in the study group. Estimated blood loss for the study group was 1,000 mL versus 800 mL in the control. Units of PRCBs transfused were 4.5 units in the study group versus 2 units for the control group. None of these measures were found to be statistically significant. Conclusion Our data suggest there was no benefit in the use of prophylactic HAL in decreasing surgical blood loss or amount of blood products transfused in patients who had a cesarean hysterectomy performed for placenta percreta. Précis Prophylactic HAL does not decrease blood loss during surgery for placenta percreta.

Increased incidence of respiratory distress syndrome in neonates of mothers with abnormally invasive placentation.

BACKGROUND: The incidence of abnormally invasive placentation (AIP) is increasing. Most of these pregnancies are delivered preterm. We sought to characterize neonatal outcomes in AIP pregnancies. METHODS: In this retrospective case-control study (2006-2015), AIP neonates (n = 108) were matched to two controls each for gestational age, antenatal glucocorticoid exposure, sex, plurity, and delivery mode. Medical records were reviewed for neonatal and maternal characteristics/outcomes. Univariate and multivariate Poisson regressions were performed to determine relative risk ratios (RR). RESULTS: There were no mortalities. All neonatal outcomes were similar except for respiratory distress syndrome (RDS), which affected 37% of AIP neonates (versus 21% of controls). AIP neonates required respiratory support (64.8% vs. 51.9%) and continuous positive airway pressure (53.7% vs. 42.1%) for a longer duration. Univariate regression yielded elevated RRs for RDS for AIP (RR 1.78, 95% CI 1.24-2.54), placenta previa (RR = 1.94, 95% CI 1.36-2.76), and placenta previa with bleeding (RR 2.29, 95% CI 1.36-3.86). One episode of bleeding had a RR of 2.43 (95% CI 1.57-3.76), 2 or more episodes had a RR of 2.95 (95% CI 1.96-4.44), and bleeding/abruption as the delivery indication had a RR of 2.57 (95% CI 1.82-3.64). A multivariate regression stratifying for AIP and evaluating the combined and individual associations of AIP, bleeding, placenta previa, and GA, resulted in elevated RRs for placenta previa alone (RR 2.16, 95% CI 1.15-4.06) and placenta previa and bleeding (RR 1.69, 95% CI 1.001-2.85). CONCLUSIONS: The increased incidence of RDS at later gestational ages in AIP is driven by placenta previa. AIP neonates required respiratory support for a longer duration than age-matched controls. Providers should be prepared to counsel expectant parents and care for affected neonates.

Use of the Tei Index in the Conservative Management of TRAP Sequence Pregnancies Diagnosed during the Periviable Period: A Case Series.

Twin Reverse Arterial Perfusion (TRAP) Sequence is a rare complication of monochorionic pregnancies. Without intervention, the viable pump twin in a case of TRAP Sequence may develop high output cardiac failure leading to an intrauterine fetal demise. We present 3 cases of TRAP Sequence pregnancy diagnosed during the second or third trimesters of pregnancy. There are minimal sonographic tools for the guidance of a fetal therapeutic interventional procedure during the second trimester or timing of delivery during the third trimester to reduce morbidity and mortality of a viable fetus. Tei index may be a useful sonographic tool in the management of TRAP Sequence during the second or third trimester of pregnancy.

Human trophoblast epithelial-mesenchymal transition in abnormally invasive placenta.

Differentiation of first trimester human placental cytotrophoblast (CTB) from an anchorage-dependent epithelial phenotype into the mesenchymal-like invasive extravillous trophoblast (EVT) is crucial in the development of the maternal-fetal interface. We showed previously that differentiation of first trimester CTB to EVT involves an epithelial-mesenchymal transition (EMT). Here we compare the epithelial-mesenchymal characteristics of CTB and EVT derived from normal third trimester placenta or placenta previa versus abnormally invasive placenta (AIP). CTB and EVT were isolated from normal term placenta or placenta previa following Caesarean section and EVT from AIP following Caesarean hysterectomy. Cell identity was validated by measurement of cytokeratin-7 and HLA-G. Comparing normal term CTB with EVT from normal term placenta or placenta previa for differential expression analysis of genes associated with the EMT showed changes in >70% of the genes probed. While demonstrating a mesenchymal phenotype relative to CTB, many of the gene expression changes in third trimester EVT were reduced relative to the first trimester EVT. We suggest that third trimester EVT are in a more constrained, metastable state compared to first trimester equivalents. By contrast, EVT from AIP demonstrate characteristics that are more mesenchymal than normal third trimester EVT, placing them closer to first trimester EVT on the EMT spectrum, consistent with a more invasive phenotype.