Sonographic prenatal diagnosis of marginal placental cord insertion: clinical importance

Placental and Umbilical Cord Anomalies Detected by Ultrasound as Clinical Risk Factors of Adverse Perinatal Outcome: Case Series Review of Selected Conditions. Part 2: Umbilical Cord Abnormalities

The aim of this second extended review is to describe the pathogenetic mechanisms underlying umbilical cord (UC) anomalies and their relationship with adverse perinatal outcomes. Review of the literature with case presentations to illustrate the relationship between UC pathologies and adverse perinatal outcomes are also reported. Prenatal ultrasound findings and perinatal care in these cases are presented. Our review confirms the ethiopathogenetic role and involvement of UC pathology in a wide variety of obstetric diseases that may jeopardize fetal well-being. Some of these specific pathologies are strongly associated with a high risk of poor perinatal outcomes.

Umbilical Cord Abnormalities

The umbilical cord is the connection between mother and fetus through which gases and nutrients are exchanged. It's remarkable structure allows for freedom of movement while providing a cushioned, protected conduit from mother to fetus. Fetal development and survival are dependent upon the umbilical cord. This article reviews abnormalities of the umbilical cord that can be seen with structural and chromosomal abnormalities and altered umbilical cord flow associated with fetal growth restriction and poor pregnancy outcomes.

Imaging of the Placenta

Placental imaging is crucial in prenatal care, offering insights into both normal and abnormal pregnancies. Traditional methods like grayscale ultrasound and magnetic resonance imaging evaluate placental anatomy, whereas Doppler ultrasound is used for functional assessment. Recent advancements include functional magnetic resonance imaging and advanced Doppler software for demonstrating placental density and visualizing spiral arteries. B-flow and spatio-temporal image correlation are pivotal, sensitive tools for quantifying spiral artery distensibility and volume flow in early pregnancy. These techniques enhance our understanding of placental vascular architecture and promise early diagnosis and intervention for pregnancies at risk. This paper emphasizes the importance of advanced imaging in prenatal care.

Placental cord insertion migration: Implications for ultrasound documentation and follow-up of abnormal placental cord insertion site

Introduction/Purpose

It is well-documented in the literature that the placenta migrates during pregnancy; however, studies regarding placental cord insertion (PCI) migration are scarce. This longitudinal, prospective study aimed to determine whether PCI migration is a true phenomenon, to assess whether the PCI can change classification during pregnancy and to determine the validity of PCI site documentation including follow-up of abnormal PCI.

Methods

Eighty-three participants who had first, second and third trimester ultrasound examinations at a Western Australian private imaging practice over a 12-month period between November 2021 and November 2022 were recruited. The measured distance of the lower margin of the placenta to the cervix, the distance of the PCI to the closest placental edge and the PCI classification were documented in each trimester. Data analysis was conducted to determine PCI migration rates during pregnancy and to test for association between PCI migration and maternal and placental factors.

Results

The PCI migrated during pregnancy and the PCI classification has the potential to evolve. All identifiable PCIs that were normal in first trimester remained so throughout the pregnancy. The majority (67.6%) of cord insertions that were marginal in first trimester progressed to a normal insertion site by third trimester; 23.5% remained marginal and 8.8% evolved to a velamentous insertion. Three velamentous cord insertions were recorded in first trimester, none of which normalised-two remained velamentous during the pregnancy and one evolved to marginal in second trimester. Marginal cord insertions (MCIs) ≤10 mm from the placental edge in second trimester remained marginal in third trimester; MCIs that were >15 mm from the placental edge in second trimester normalised in third trimester.

Conclusions

Placental cord insertion migration is a phenomenon that occurs during pregnancy with the potential for PCI classification to evolve. Due to the association between abnormal PCI and perinatal complications, coupled with the potential for marginal cord insertion to evolve, documentation of PCI and follow-up of abnormal PCI is beneficial, particularly in cases of velamentous insertion and marginal insertion at the placental edge or in the lower uterus.

Marginal cord insertion in the first trimester is associated with furcate cord insertion

OBJECTIVES

To evaluate the potential connections between marginal cord insertion during the first trimester and furcate cord insertion later in pregnancy.

METHODS

This is a prospective study of screening data on the cord insertion site in 3178 singleton pregnancies. The cord insertion site was examined in two stages. The first stage was screening for the cord insertion site between 10-13 weeks of gestation, the purpose is to determine the category of umbilical cord insertion. The second stage, performed at 22-28 weeks of gestation, was to follow up on the relationship between the cord insertion site and the placenta and to identify any changes in the category of umbilical cord insertion. This was performed to diagnose or exclude furcate cord insertion by identifying whether the umbilical cord trunk separated or branched before it reached the placenta. Factors influencing progression to furcate cord insertion and perinatal complications were assessed.

RESULTS

Fourteen cases (0.44%) with progression to furcate cord insertion, all of which showed marginal cord insertion on ultrasound in the first trimester (p < 0.001). without progression to furcate cord insertion, there were no changes in the category of umbilical cord insertion in 3050 cases (96.40%) compared to the early pregnancy. 114 cases (3.60%) with changes in the category of umbilical cord insertion that was not consistent with furcate cord insertion. A total of 14 cases progressed to furcate cord insertion, all showed the cord insertion site were in close proximity, and 11 (78.57%) cases showed a low insertion site (p < 0.001). Regarding the choice of mode of delivery, elective caesarean delivery was done in 8/14 (57.14%). The incidences of spontaneous vaginal delivery were 5/14 (35.71%) (p < 0.001). One (7.14%) case of progression to furcate cord insertion due to haematoma at the root of the umbilical cord ended with an emergency caesarean section. In terms of perinatal complications, marginal cord insertion that progressed to furcate cord insertion had higher incidences of SGA infants, abnormal placental morphology, retention of the placenta, and cord-related adverse pregnancy outcomes than not progressed to furcate cord insertion (p < 0.05).

CONCLUSIONS

Marginal cord insertion in the first trimester has the potential to progress to furcate cord insertion. We suggest that ultrasound-diagnosed marginal cord insertion in the first trimester should be watched carefully in the second trimester, which is clinically useful to accurately determine the category of cord insertion and to improve the rate of prenatal diagnosis of furcate cord insertion.

Peripheral cord insertion is associated with adverse pregnancy outcome only when accompanied by clinically significant placental pathology

OBJECTIVE

To examine the relationship between umbilical cord insertion site, placental pathology and adverse pregnancy outcome in a cohort of normal and complicated pregnancies.

METHODS

Sonographic measurement of the cord insertion and detailed placental pathology were performed in 309 participants. Associations between cord insertion site, placental pathology and adverse pregnancy outcome (pre-eclampsia, preterm birth, small-for-gestational age) were examined.

RESULTS

A total of 93 (30%) participants were identified by pathological examination to have a peripheral cord insertion site. Only 41 of the 93 (44%) peripheral cords were detected by prenatal ultrasound. Peripherally inserted cords were associated significantly (P < 0.0001) with diagnostic placental pathology (most commonly with maternal vascular malperfusion (MVM)); of which 85% had an adverse pregnancy outcome. In cases of isolated peripheral cords, without placental pathology, the incidence of adverse outcome was not statistically different when compared to those with central cord insertion and no placental pathology (31% vs 18%; P = 0.3). A peripheral cord with an abnormal umbilical artery (UA) pulsatility index (PI) corresponded to an adverse outcome in 96% of cases compared to 29% when the UA-PI was normal.

CONCLUSIONS

This study demonstrates that peripheral cord insertion is often part of the spectrum of findings of MVM disease and is associated with adverse pregnancy outcome. However, adverse outcome was uncommon when there was an isolated peripheral cord insertion and no placental pathology. Therefore, additional sonographic and biochemical features of MVM should be sought when a peripheral cord is observed. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Current practice of placental cord insertion documentation in Australia - A sonographer survey

Introduction

During pregnancy, the umbilical cord attaches to the placenta in a central, eccentric, marginal or velamentous location. Maternal and fetal complications are associated with marginal and velamentous cord insertions, the most clinically significant being perinatal mortality due to undiagnosed vasa praevia. Current literature describes a wide variation regarding regulation of placental cord insertion (PCI) documentation during antenatal ultrasound examinations. This prospective cross-sectional study aimed to assess the current practice of antenatal PCI documentation in Australia.

Methods

Members of the Australian Sonographer Accreditation Registry were invited to participate in an online survey which was distributed between February and March 2022.

Results

Four hundred ninety sonographers met the inclusion criteria for the study of which 330 (67.3%) have more than 10 years' experience as a sonographer and 375 (76.5%) are employed primarily in a public or private setting offering general ultrasound. Most respondents (89.6%) indicated documentation of the PCI site is departmental protocol at the second trimester anatomy scan (17-22 weeks gestation), but PCI documentation is protocol in less than 50% of other obstetric ultrasound examinations listed in the survey. The PCI site is included in the formal ultrasound report at a rate significantly less than inclusion in the departmental protocol and the sonographer's worksheet.

Conclusions

Considering the potential maternal and fetal complications associated with abnormal PCI and the ease at which the PCI site is identified in the first and second trimesters, we believe that standard inclusion of the PCI site in departmental protocol and in the formal ultrasound report from 11 weeks gestation, regardless of whether it is normal or abnormal, would prove invaluable.

Impact of Marginal and Velamentous Cord Insertion on Uterine Artery Doppler Indices, Fetal Growth, and Preeclampsia

OBJECTIVES

To assess the impact of marginal (MCI) or velamentous (VCI) cord insertion on uterine artery pulsatility index (UtA PI), preeclampsia (PE), and offspring's birthweight (BW).

METHODS

A retrospective cohort study of singleton pregnancies, undergoing routine anomaly scan at 20⁺⁰ -23⁺⁶ gestational weeks, was conducted between 2016 and 2020. The effect of placental cord insertion on BW and UtA mean PI z-scores was assessed using the t test or analysis of variance and post-hoc tests; their association with PE was evaluated with the chi-square test. A multivariate logistic regression model was employed to assess the independent association of placental cord insertion and UtA PI z-score with PE, BW <10th, <5th centile, and intrauterine death (IUD), using specific confounders.

RESULTS

The study population included 4453 pregnancies. Conception via assisted reproductive technology (ART) was associated with increased risk of abnormal cord insertion (odds ratio [OR]: 2.237; 95% confidence interval [CI]: 1.561-3.206; P < .001). Women with MCI/VCI had higher mean UtA PI z-score than those with central/eccentric (0.29 vs 0.01; mean difference: -0.28; 95% CI: -0.399 to -0.165; P < .001). MCI/VCI were associated with higher rates of BW <10th centile (central/eccentric: 16.2% vs MCI: 21.9% vs VCI: 35.7%; P < .001) and BW <5th centile (9.8 vs 15.1 vs 23.2%, respectively; P < .001). No association was identified between MCI/VCI and PE (P = .968). Finally, VCI (aOR: 13.717; 95% CI: 1.576-119.379; P = .018) and increased BMI (aOR: 1.167; 95% CI: 1.071-1.271; P < .001) significantly correlated with IUD.

CONCLUSIONS

Abnormal cord insertion is more common in ART pregnancies. MCI/VCI are associated with higher mean UtA PI and lower BW centile, but not with increased risk of PE.

Sonographic Diagnosis of Velamentous and Marginal Placental Cord Insertion

Routine second trimester ultrasound (US) examinations include an assessment of the umbilical cord given its vital role as a vascular conduit between the maternal placenta and fetus during fetal development. Placental cord insertion abnormalities can be identified during prenatal US screening and are increasingly recognized as independent risk factors for various complications during pregnancy and delivery. The purpose of this pictorial review is to illustrate examples of velamentous and marginal placental cord insertion with an emphasis on how to differentiate their morphology using color Doppler US.

Performance of ultrasound for the visualization of the placental cord insertion

PURPOSE OF REVIEW

The purpose of this review was to review the literature on the performance of ultrasound for the visualization of the placental cord insertion (PCI) and for the diagnosis of abnormal placental cord insertion (APCI). APCI included both marginal cord insertion (MCI) and velamentous cord insertion (VCI) PCI.

RECENT FINDINGS

The overall rate of visualization of the PCI across all trimesters is 90.3% and for those studies routinely using color Doppler, 98.1% (P < 0.0001). Although the visualization was lower with advancing gestational age, it remained high even into the late third trimester. In all studies, where time was reported, the PCI was visualized in most cases in less than 1 min. Ultrasound performed best for the diagnosis of VCI with a sensitivity, specificity and positive predictive value of 100, 99.9 and 85.7%, respectively, with routine use of color Doppler.

SUMMARY

Ultrasound is an excellent screening test for the evaluation of PCI across all trimesters. The use of color Doppler increases the rate of visualization and should be routinely used. Ultrasound with color Doppler is also an excellent screening test for the diagnosis of VCI. However, the performance of ultrasound is reduced with the inclusion of MCI.

Placental cord insertion distance from the placental margin and its association with adverse perinatal outcomes

OBJECTIVE

The placental cord insertion (PCI) to the placental margin has not been well studied as a continuous variable in relation to birth outcomes. We sought to evaluate the impact of PCI distance on outcomes associated with placental function and development of fetal growth restriction (FGR).

STUDY DESIGN

This was a retrospective study of singleton gestations that underwent a fetal anatomy ultrasound from 2011-2013. The PCI was recorded as the distance in centimeters from the placental margin. Patients had FGR if the overall estimated fetal weight was <10 % for gestational age or abdominal circumference <5 % in the third trimester. Delivery, obstetric, and neonatal outcomes were obtained via medical chart review. Logistic and linear regression models were used to assess the impact of PCI distance on maternal and neonatal delivery outcomes.

RESULTS

Of the 1443 women who met inclusion criteria, 93.6 % delivered at term. The mean (±SD) PCI distance was 4.4 ± 1.4 cm. There was no association between PCI and cesarean delivery, peripartum hemorrhage (PPH), pre-eclampsia, 5-min Apgar, or intrauterine fetal demise. PCI distance was statistically significantly shorter in patients requiring neonatal intensive care unit (NICU) admission (4.1 ± 1.5 cm vs. 4.4 ± 1.4 cm, p = 0.02) and was associated with lower birthweight (p = 0.01), though this association was no longer seen when corrected for gestational age. There were 3.5 % of patients who developed FGR; PCI distances from the placental edge were not significantly different for patients who developed FGR compared to those who did not (4.2 ± 1.4 cm vs. 4.5 ± 1.4 cm, p = 0.18). Furthermore, a receiver operating characteristic (ROC) curve for PCI had poor sensitivity (area under the curve [AUC] 0.57, 95 % CI 0.49-0.65).

CONCLUSION

PCI distance at the time of fetal anatomic survey is significantly associated with NICU admission, though does not appear to impact rates of preterm birth, pre-eclampsia, PPH or cesarean delivery. PCI distance in singleton gestations does not appear to be predictive of FGR.

Antenatal Diagnosis of Marginal and Velamentous Placental Cord Insertion and Pregnancy Outcomes

OBJECTIVE

To evaluate the association between antenatal diagnosis of velamentous and marginal placental cord insertions with adverse perinatal outcomes of small-for-gestational-age (SGA) birth weight (less than the 5th percentile), caesarean birth, and perinatal mortality.

METHODS

Using a diagnostic imaging database, we performed a cohort study of all consecutive singleton pregnancies (35,391), including 1,427 cases of marginal and 107 cases of velamentous cord insertion, delivered after 24 6/7 weeks of gestation between January 1, 2012, and December 31, 2015, at a single Canadian tertiary care center. Cases with placenta previa, vasa previa, no documented cord insertion, or fetal anomalies were excluded.

RESULTS

In the overall cohort, the rate of birth weight less than the 5th percentile was 5.2%, the rate of cesarean delivery was 27.1%, and the rate of perinatal mortality was 0.24%. Velamentous cord insertion was associated with SGA (relative risk [RR] 2.19, 95% CI 1.28-3.74). This persisted after controlling for smoking during pregnancy, diabetes, and hypertension (adjusted odds ratio [aOR] 1.98, 95% CI 1.03-3.84). Velamentous cord insertion was also associated with an increased risk of caesarean birth (RR=1.38, 95% CI=1.08-1,77) and perinatal death (1.87%, RR 8.15, 95% CI 2.02-32.8), a relationship that persisted after controlling for smoking during pregnancy, diabetes, and hypertension (aOR 1.53, 95% CI 1.01-2.32). Marginal cord insertion was not associated with birth weight less than the 5th percentile (RR 1.23, 95% CI 1.00-1.51), cesarean delivery (RR 1.01, 95% CI 0.92-1.10), or perinatal death (RR 1.53, 95% CI 0.62-3.78).

CONCLUSION

Antenatal diagnosis of velamentous placental cord insertion is associated with birth weight less than the 5th percentile.

Placental vascular tree characterization based on ex-vivo MRI with a potential application for placental insufficiency assessment

INTRODUCTION

Understanding regarding the whole placental vascular network structure is limited. Our aim was to quantitatively characterize the human placental vascular tree ex-vivo using high-resolution MRI.

METHODS

34 normal placentas were rinsed and injected with a solution of gelatin and contrast agent through the umbilical vessels. A sample of six placentas taken from pregnancies with intrauterine-growth-restriction (IUGR) was used to demonstrate the potential application to cases with placental insufficiency. Structural ex-vivo MR scans of the placenta were performed using high resolution T₁ weighted images. A semi-automatic method was developed to segment and characterize the placental vascular architecture: placental volume and cord insertion location; number of bifurcations, generations and vessels diameters.

RESULTS

Different vascular patterns were found in placentas with central versus marginal cord-insertion. Based on the placental volume and number of bifurcations we were able to predict birth weight. Furthermore, preliminary results on IUGR sample demonstrated the potential of this method to differentiate between small newborns with suspected IUGR from small normal newborns who reached their full growth potential. Results obtained using the automatic method were validated against manual values demonstrating no significant differences or bias. Histopathology supported the imaging findings.

DISCUSSION

This is the first study to quantitatively characterize the human placental vascular architecture using high resolution ex-vivo MRI. Different patterns of vascular architecture may be related to different functioning of the placenta and affect fetal development. This method is simple, relatively fast, provides detailed information of the placental vascular architecture, and may have important clinical applications.

Placental vascular tree characterization based on ex-vivo MRI with a potential application for placental insufficiency assessment

INTRODUCTION

Understanding regarding the whole placental vascular network structure is limited. Our aim was to quantitatively characterize the human placental vascular tree ex-vivo using high-resolution MRI.

METHODS

34 normal placentas were rinsed and injected with a solution of gelatin and contrast agent through the umbilical vessels. A sample of six placentas taken from pregnancies with intrauterine-growth-restriction (IUGR) was used to demonstrate the potential application to cases with placental insufficiency. Structural ex-vivo MR scans of the placenta were performed using high resolution T₁ weighted images. A semi-automatic method was developed to segment and characterize the placental vascular architecture: placental volume and cord insertion location, number of bifurcations, generations and vessels diameters.

RESULTS

Different vascular patterns were found in placentas with central versus marginal cord-insertion. Based on the placental volume and number of bifurcations we were able to predict birth weight. Furthermore, preliminary results on IUGR sample demonstrated the potential of this method to differentiate between small newborns with suspected IUGR from small normal newborns who reached their full growth potential. Results obtained using the automatic method were validated against manual values demonstrating no significant differences or bias. Histopathology supported the imaging findings.

DISCUSSION

This is the first study to quantitatively characterize the human placental vascular architecture using high resolution ex-vivo MRI. Different patterns of vascular architecture may be related to different functioning of the placenta and affect fetal development. This method is simple, relatively fast, provides detailed information of the placental vascular architecture, and may have important clinical applications.

Marginal placental cord insertion: the need for follow up?

Objective: The objectives of this study were (1) to estimate the association between marginal placental cord insertion (PCI) and small for gestational age (SGA) and other adverse perinatal outcomes and (2) to determine if pregnancy-associated plasma protein A (PAPP-A) levels was altered in these patients.Methods: It was a retrospective cohort study of singleton pregnancies undergoing ultrasound between 2016 and 2018. Marginal PCI was defined as a distance of ≤2 cm from placental edge to PCI site, visualized in both sagittal and transverse planes, and diagnosed between 16 and 32 weeks. Velamentous PCI were excluded. The primary outcome was SGA, defined as birthweight below 10th percentile for gestational age. Pregnancies with marginal PCI were compared to those with normal PCI with respect to maternal characteristics, PAPP-A levels and adverse perinatal and delivery outcomes.Results: The incidence of marginal PCI was 4.2% (76/1819). Compared to those with a normal PCI, patients with a marginal PCI were more likely to be nulliparous and less likely to be African American or morbidly obese (p < .05). SGA rate was similar between the groups (17.6% vs. 18.1%). There was a trend toward an increased incidence of oligohydramnios, polyhydramnios and breech presentation in patients with marginal PCI; however, these did not reach statistical significance. The incidence of low PAPP-A level was comparable between the groups (18.4% vs. 14.3%, p > .05).Conclusion: Our study did not demonstrate any increase in adverse pregnancy outcomes in the presence of marginal PCI. These findings may provide reassurance for counseling patients with this sonographic finding.

Second-Trimester Ultrasound-Measured Umbilical Cord Insertion-to-Placental Edge Distance: Determining an Outcome-Based Threshold for Identifying Marginal Cord Insertions

OBJECTIVES

We sought to study potential diagnostic criteria for marginal placental cord insertions as determined by associations with obstetric outcomes.

METHODS

This single-center retrospective cohort investigation included singleton gestations delivering from January 1, 2012, to December 31, 2016, and having a standard or detailed fetal ultrasound examination from 18 weeks to 21 weeks 6 days. Cord insertion-to-placental edge distances were used to create a referent comparison group and 3 patient groups: greater than 3.0 cm (comparison); greater than 2.0 to 3.0 cm (group 1); greater than 1.0 to 2.0 cm (group 2); and 1.0 cm or less (group 3). The primary outcome consisted of any one of spontaneous delivery before 37 weeks, fetal growth restriction, oligohydramnios, placental abruption, or intrauterine fetal demise.

RESULTS

The numbers of participants and mean distances ± SDs for the comparison group and groups 1 to 3, respectively, were 628 and 4.68 ± 1.17 cm, 106 and 2.52 ± 0.26 cm, 131 and 1.60 ± 0.29 cm, and 77 and 0.36 ± 0.37 cm, respectively. The primary outcome was significantly associated only with cord insertion-to-placental edge distances of 1.0 cm or less (adjusted odds ratio, 3.05; 95% confidence interval, 1.73-5.38).

CONCLUSIONS

Marginal cord insertions may be diagnosed when the cord insertion-to-placental edge distance is 1.0 cm or less.

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.

First trimester ultrasound prediction of velamentous cord insertions: a prospective study

INTRODUCTION

The marginal and velamentous cord insertions complicate around 8% of pregnancies and are at higher risk of adverse perinatal outcomes. Their visualisation seems to decrease with advancing gestational age. Our aim was to analyse whether an umbilical cord insertion in the lower third of the uterus during the first trimester could predict abnormal cord insertions later in pregnancy.

METHODS

This was a prospective multicentre study in two hospitals. During the first trimester, the cord insertions were inspected as well as their location (lower third of the uterus or not). Finally, all cord insertions were described at delivery.

RESULTS

During the study period the cord insertion was described in 1620 patients of which 87.7% had a normal cord insertion, 11.9% (n = 192) a low cord insertion, and in 3.8% the insertion could not be situated. We find that 4.7% of those who have a low-lying cord insertion versus 0.7% in the normal cord insertion group during the first trimester will have a velamentous cord insertion subsequently (OR = 6.67; 95% CI = 2.67-16.63).

CONCLUSION

The detection of a low lying umbilical cord insertion during the first-trimester ultrasound can help to predict an abnormal cord insertion at delivery particularly a velamentous cord insertion.

Second trimester marginal cord insertion is associated with adverse perinatal outcomes

Objectives: To determine the feasibility in visualizing placental cord insertion (PCI) during second-trimester fetal anatomical survey and the association between marginal cord insertion (MCI) and preterm delivery (PTD) and low birth weight (LBW). Our secondary objectives were to evaluate the association of MCI with adverse composite obstetrical and neonatal outcomes. Methods: A prospective cohort study was performed over a 28-month period. Women with singleton pregnancies presenting for routine anatomical survey between 18 and 22 weeks' gestation were included. PCI site was visualized on 2D grayscale and color Doppler and the shortest distance from the sagittal and transverse planes to the placental edge were recorded. MCI was diagnosed when any of measured distances was ≤2 cm. Correlations were assessed via bivariate chi-squared, independent t-test analyses and Fisher's exact tests. Regression models evaluated associations between MCI and adverse composite outcomes. Results: Three hundred one women were included and PCI was feasible in all cases. The incidence of MCI was 11.3% (n = 34). Baseline characteristics between those with and without MCI were similar, except for story of prior PTD, which was greater among those with MCI (17.65 versus 7.17%, p = .04). MCI was associated with increased likelihood of LBW (RR four; 95%CI, 1.46-10.99) and PTD (RR 3.2; 95%CI, 1.53-6.68); in multivariate analysis, we found associations between MCI and composite adverse obstetrical (RR 2.33; 95%CI, 1.30-4.19) and neonatal (RR 2.46; 95%CI, 1.26-4.81) outcomes. Conclusions: Evaluation of PCI is feasible in all cases. Second-trimester MCI is associated with increased likelihood for LBW, PTD, and composite adverse obstetrical and neonatal outcomes.

Placental Imaging: Normal Appearance with Review of Pathologic Findings

The placenta plays a crucial role throughout pregnancy, and its importance may be overlooked during routine antenatal imaging evaluation. Detailed systematic assessment of the placenta at ultrasonography (US), the standard imaging examination during pregnancy, is important. Familiarity with the normal and abnormal imaging appearance of the placenta along with the multimodality and methodical approach for evaluation of its related abnormalities is necessary, so that radiologists can alert clinicians regarding appropriate prompt management decisions. This will potentially decrease fetal and maternal morbidity and mortality. This article reviews early placental formation and the expected imaging appearance of the placenta during pregnancy, as well as variations in its morphology. It also discusses various placental diseases and their potential clinical consequences. Placental pathologic conditions include abnormalities of placental size, cord insertion, placental and cord location, and placental adherence. Other conditions such as bleeding in and around the placenta, as well as trophoblastic and nontrophoblastic tumors of the placenta, are also discussed. US with Doppler imaging is the initial imaging modality of choice for placental evaluation. Magnetic resonance (MR) imaging is reserved for equivocal cases or when additional information is needed. Computed tomography (CT) has a limited role in evaluation of placental abnormalities because of the ionizing radiation exposure and the relatively limited assessment of the placenta; however, CT can provide important information in specific circumstances, particularly evaluation of trauma and staging of choriocarcinoma. This article also addresses recent techniques and updates in placental imaging, including elastography, diffusion-weighted MR imaging, and blood oxygen level-dependent (BOLD) MR imaging. These advanced imaging techniques may provide additional information in evaluation of abnormal placental adherence and new insights into placental pathophysiology in selected patients. Online supplemental material is available for this article. ^©RSNA, 2017.

Is complete umbilical cord scanning possible at the second-trimester ultrasound scan?

PURPOSE

To evaluate the feasibility of umbilical cord scanning during the second-trimester sonographic examination, we looked at the method of scanning, the findings, and the time spent.

METHODS

Five hundred forty-nine singleton pregnancies were evaluated at 18-23 weeks' menstrual age with two-dimensional sonography (US). Color Doppler US was used when needed. The umbilical cord was traced from the fetal insertion site to the placental insertion site. Fetal and placental sites of insertion; number of vessels; presence of knots, cysts, tumors, nuchal cords, or placental anomalies; time spent for scanning; and the use of color Doppler US were noted.

RESULTS

The mean maternal age was 33.1 ± 4.1 years, and the mean menstrual age of the fetuses during scanning was 20.4 ± 2.4 weeks. The mean time spent for umbilical cord scanning was 41.5 ± 46.7 seconds. In one case (0.2%), the umbilical cord could not be scanned completely. Color Doppler US was needed in 125 (22.8%) of the scans. Scan results were positive in 153 (27.9%) cases. We observed six cases (1.1%) of a single umbilical artery, two (0.4%) umbilical cord knots, one (0.2%) umbilical cord hernia, and 104 (18.9%) nuchal cords. We also documented 27 (5.0%) marginal insertions, four placenta previa totalis (0.7%), four placenta previa marginalis (0.7%), and eight velamentous insertions (1.5%).

CONCLUSIONS

Umbilical cord US scanning is feasible during the second trimester of pregnancy, and complete scanning can be performed in the majority of the cases. Color Doppler analysis may aid scanning when needed. © 2014 Wiley Periodicals, Inc. J Clin Ultrasound 43:249-253, 2015.

A practical approach to fetal growth restriction

Fetal growth restriction is one of the most complex problems encountered by obstetricians. Ultrasound-estimated fetal weight less than the 10th percentile for the gestational age is the most widely accepted diagnostic criterion. Management protocols vary from institution to institution. Doppler velocimetry provides valuable information about fetal status. We offer a practical approach to management and timing of delivery based on available data in the literature.

Comprehensive imaging review of abnormalities of the umbilical cord

A complete fetal ultrasonographic (US) study includes assessment of the umbilical cord for possible abnormalities. Knowledge of the normal appearance of the umbilical cord is necessary for the radiologist to correctly diagnose pathologic conditions. Umbilical cord abnormalities can be related to cord coiling, length, and thickness; the placental insertion site; in utero distortion; vascular abnormalities; and primary tumors or masses. These conditions may be associated with other fetal anomalies and aneuploidies, and their discovery should prompt a thorough fetal US examination. Further workup and planning for a safe fetal delivery may include fetal echocardiography and karyotype analysis. Doppler US is a critical tool for assessment and diagnosis of vascular cord abnormalities. US also can be used for follow-up serial imaging evaluation of conditions that could result in fetal demise. Recent studies suggest that three- or four-dimensional Doppler US of the fetal umbilical cord and abdominal vasculature allows more accurate diagnosis of vascular abnormalities. Doppler US also is invaluable in assessment of fetal growth restriction since hemodynamic changes in the placenta or fetus would appear as a spectral pattern of increased resistance to forward flow in the fetal umbilical artery. Early detection of umbilical cord abnormalities and close follow-up can reduce the risk of morbidity and mortality and assist in decision making.

Influence of the umbilical cord insertion site on the optimal individual birth weight achievement

Study Question. To determine whether the umbilical cord insertion site of singleton pregnancies could be linked to the newborn birth weight at term and its individual growth potential achievement. Material and Methods. A cohort study including 528 records of term neonates was performed. Each neonate was assessed for growth adjusted for gestational age according to the infant's growth potential using the AUDIPOG module. We considered two categories of umbilical cord insertions: central and peripheral. Intrauterine growth restriction was defined as birth weight below the 10th percentile. Statistical analysis was performed using Chi-square, Student's t test, Wilcoxon test, ANOVA, and logistic regression. Results. We observed a total of 343 centrally inserted cords versus 185 peripheral cords. There were twice as many smokers in the mothers of the peripheral category compared to the centrally inserted ones. More importantly, we demonstrated that only 17/343 (5.0%) of infants with central cord insertion were growth restricted, compared to 37/185 (20.0%) of the infants born with a peripheral insertion. Neonates with centrally inserted cord were significantly heavier. Conclusion. The umbilical cord insertion site of singleton pregnancies is associated with the newborn's birth weight at term and its individual growth potential achievement.

Peripheral insertion of umbilical cord

Numerous studies have addressed the significance of marginal and membranous umbilical cord (UC) insertion. Recent reports suggest that an eccentrically inserted UC may also be important. This case-control study assessed the potential relevance of peripheral insertion of UC (PIUC), defined as <3 cm from the nearest margin. Singleton placentas (n  =  1418) submitted to the pathology department over an 18-month period were analyzed. Each case of PIUC (n  =  119) was matched with a control placenta of the same gestational age. Placentas with marginal or membranous UC and multiple gestations were excluded. The overall prevalence of PIUC was 8.4%, but PIUC frequency was significantly increased in premature births at <28 weeks (21.4%, P < 0.001). There was no association with other adverse pregnancy outcomes. PIUC was associated with decreased placental weight Z-score (-0.69 ± 0.92 versus -0.22 ± 1.3, P  =  0.0056), but not fetal weight Z-score, suggesting increased utilization of placental reserve. PIUC was also associated with relatively elongated placentas (length minus width: 2.6 ± 3.2 versus 1.0 ± 3.1, P  =  0.006). PIUC tended to be more frequent in young primiparous mothers and was significantly less common in women with a history of prior curettage (66% vs 50%, P  =  0.013). These data, together with equivalent rates of prior cesarean section, multiparity, and advanced maternal age, support a primary developmental disorder as opposed to secondary placental migration due to underlying uterine abnormalities ("trophotropism"). Except for a borderline significant association with findings suggestive of maternal malperfusion (P  =  0.078), PIUC was not associated with other placental lesions.

Unequal placental sharing and birth weight discordance in monochorionic diamniotic twins

OBJECTIVE

The purpose of this study was to define the association between unequal placental sharing and birth weight discordance in monochorionic/diamniotic twin pregnancies.

STUDY DESIGN

The study comprised a prospective cohort of monochorionic/diamniotic twin pregnancies who were delivered in Kaiser Permanente-Northern California, 1997-2003. Dye injection studies of fresh postpartum placentas were performed. Placental sharing, cord insertion combinations, vascular anastomoses, gestational age, and birth weights were recorded. Statistical comparisons of birth weight and gestational age were made with the Student t test. Rates of birth weight discordance were compared with the chi-square test. Multivariate logistic regression models analyzed the relationship between variables of interest.

RESULTS

Mean birth weights for larger and smaller twins were 2400 g and 2109 g, respectively. Twenty-two percent of the monochorionic/diamniotic twin pairs had birth weight discordance > or = 20%, and 8% of these pairs had twin-twin transfusion syndrome. Monochorionic/diamniotic twin pairs with unequal placental sharing had a 9.8 times greater likelihood of birth weight discordance (95% CI, 5.4-17.9) as compared with those pairs with equal placental sharing.

CONCLUSION

Unequal placental sharing is a significant risk factor for birth weight discordance in monochorionic/diamniotic twins. Antenatal diagnosis of unequal placental sharing would enable improved counseling in the setting of monochorionic/diamniotic twins.

Ultrasound detection of placental insufficiency in women with 'unexplained' abnormal maternal serum screening results

Serious placental insufficiency results in perinatal death or preterm birth from ischemic-thrombotic pathology, a process which has its origins in placental maldevelopment in the first trimester. A proportion of at-risk pregnancies may be identified from abnormalities in first or second trimester serum screening data, uterine artery Doppler waveforms or placental shape and texture at the time of the 18-20-week anatomical examination. In combination, these tests may be capable of recognizing a subset of at-risk pregnancies with 50% positive predictive values. Early recognition before fetal viability affords opportunities to direct women to regional perinatal care centres for enhanced maternal-fetal surveillance, corticosteroids to enhance fetal lung maturation, prophylactic measures to prevent pre-eclampsia and optimal decision making around the time of delivery. The creation of regional screening programs to use screening data with a placental focus is likely to be cost-effective, because existing patterns of care are utilized. More importantly, this strategy can direct women to participate in clinical research programs designed to reduce morbidity and mortality from this common group of conditions.