Two-dimensional sonographic placental measurements in the prediction of small-for-gestational-age infants

Placental volume as a potential early marker for metabolic pertubations during pregnancy

The placenta has a central function in fetal glucose supply and placental volume has received rising awareness as a potential predicting factor for adverse pregnancy outcomes. We aimed to examine whether placental volume is a prognostic marker for metabolic perturbations affecting both mother and child. Data from 100 women participating in a longitudinal cohort study of healthy pregnant women were obtained. Placental volume was assessed via transabdominal ultrasound at gestational weeks 12-14. Additional ultrasound measurements were conducted at gestational weeks 23-25, 28-30, and 34-36 to assess fetal anthropometry. HbA1c was measured in first trimester blood samples. Both cross-sectional and prospective associations between first trimester placental volume and selected fetal and maternal parameters were examined using multivariable linear regression models. Interactions by gender were observed for associations with HbA1c, anterior abdominal wall thickness (AAWT), gestational weight gain and estimated fetal weight. A higher first trimester placental volume was related to higher HbA1c levels in the first trimester, higher AAWT measures in the third trimester, and greater gestational weight gain in women carrying a male fetus only (all p = 0.02). In women carrying a female fetus, a positive association was observed between placental volume and estimated fetal weight at gestational week 34-36 (p = 0.045). None of the other maternal or fetal parameters were related to placental volume (p ≥ 0.1). Our results indicate first trimester placental volume to be a potential prognostic factor for maternal glucose metabolism and both fetal and maternal anthropometric perturbations particularly for those mothers carrying a male fetus.

Placental biophysical model for prediction of early onset fetal growth restriction in first and second trimester of pregnancy: A prospective cohort study

INTRODUCTION

To assess the placental biometry, placental biomarkers and uterine artery Doppler in each trimester of pregnancy for prediction of early-onset fetal growth restriction (EO FGR).

METHODS

In this prospective cohort study placental biometry; biomarkers PAPP-A, sFLT-1, and PlGF along with the uterine artery blood flow evaluation was done serially at 11-14, 20-24 and 28-32 weeks of gestation. The above parameters were compared between women with early onset FGR and controls.

RESULTS

Out of 1008 fully followed cases, the small for gestational age fetuses were 227/1008 (22.5 %), and EO FGR were 84/1008(8.3 %).The placental length, volume, and PlGF levels were significantly lower, whereas the uterine artery PI(Ut PI) was significantly higher at all time points among cases. The sFLT-1 level showed a significant increase among cases, whereas it decreased among controls from the first to the second trimester. The detection rate using PV/UtA PI was 60 % in the first trimester and 66.7 % in the second trimester at 30 % FPR.

CONCLUSION

The PV/Ut PI in first and the second trimester was a good marker for the prediction of pregnancies at increased risk of developing EO FGR.

Reference Ranges of 2-Dimensional Placental Biometry and 3-Dimensional Placental Volume between 11 and 14 Weeks of Gestation

OBJECTIVE

The purpose of this study was to provide gestational age (GA) specific reference ranges for 2-dimensional (2D) placental biometry and 3-dimensional (3D) placental volume between 11 and 14 weeks of gestation.

METHODS

Placental biometry including 2D and 3D variables was calculated in 1142 first-trimester singleton pregnancies with non-complicated outcome between September 2016 and February 2020. Ultrasound datasets were obtained at the time of the first-trimester ultrasound, and 2D basal plate (BP), chorionic plate (CP), placental thickness (PT), and 3D placental volume (PV) were measured following a standardized methodology. Reference ranges for each variable were calculated according to GA and crown-rump-length (CRL).

RESULTS

A total of 1142 uncomplicated pregnancies were considered for analysis. All placental measurements increased significantly between 11 and 14 weeks, especially for PT (39.64%) and PV (64.4%). Reference ranges were constructed for each 2D and 3D first-trimester placental variable using the best-fit regression model for the predicted mean and SD as a function of GA and CRL.

CONCLUSIONS

Reference ranges of 2D placental biometry and 3D placental volume between 11 and 14 weeks of gestation were constructed, generating reference values. Placental biometry showed a progressive increase during the first trimester. This highlights the importance of using reference range charts according to GA.

How to enhance the applicability of a risk prediction model for term small-for-gestational-age neonates in clinical settings?

OBJECTIVE

To construct a simple term small-for-gestational-age (SGA) neonate prediction model that is clinically practical.

METHODS

This analysis was based on the Born in Guangzhou Cohort Study (BIGCS). Mothers who had a singleton pregnancy, delivered a term neonate, and had an ultrasonography within 30 + 0 to 32 + 6 weeks of gestation were included. Term SGA was defined with customized population percentiles. Prediction models were constructed with backward selection logistic regression in a four-step approach, where model 1 contained fetal biometrics only, models 2 and 3 included maternal features and a time factor (weeks between ultrasonography and delivery), respectively; and model 4 contained all features mentioned. The prediction performance of individual models was evaluated based on area under the curve (AUC) and a calibration test was performed.

RESULTS

The prevalence of SGA in the study population of 21 346 women was 11.5%. With a complete-case analysis approach, data of 19 954 women were used for model construction and validation. The AUC of the four models were 0.781, 0.793, 0.823, and 0.834, respectively, and all were well-calibrated. Model 3 consisted of fetal biometrics and corrected for time to delivery was chosen as the final model to build risk prediction graphs for clinical use.

CONCLUSION

A prediction model derived from fetal biometrics in early third trimester is satisfactory to predict SGA.

Multi-centre deep learning for placenta segmentation in obstetric ultrasound with multi-observer and cross-country generalization

The placenta is crucial to fetal well-being and it plays a significant role in the pathogenesis of hypertensive pregnancy disorders. Moreover, a timely diagnosis of placenta previa may save lives. Ultrasound is the primary imaging modality in pregnancy, but high-quality imaging depends on the access to equipment and staff, which is not possible in all settings. Convolutional neural networks may help standardize the acquisition of images for fetal diagnostics. Our aim was to develop a deep learning based model for classification and segmentation of the placenta in ultrasound images. We trained a model based on manual annotations of 7,500 ultrasound images to identify and segment the placenta. The model's performance was compared to annotations made by 25 clinicians (experts, trainees, midwives). The overall image classification accuracy was 81%. The average intersection over union score (IoU) reached 0.78. The model's accuracy was lower than experts' and trainees', but it outperformed all clinicians at delineating the placenta, IoU = 0.75 vs 0.69, 0.66, 0.59. The model was cross validated on 100 2nd trimester images from Barcelona, yielding an accuracy of 76%, IoU 0.68. In conclusion, we developed a model for automatic classification and segmentation of the placenta with consistent performance across different patient populations. It may be used for automated detection of placenta previa and enable future deep learning research in placental dysfunction.

Fully Automated Placental Volume Quantification From 3D Ultrasound for Prediction of Small-for-Gestational-Age Infants

OBJECTIVES

Early placental volume (PV) has been associated with small-for-gestational-age infants born under the 10th/5th centiles (SGA10/SGA5). Manual or semiautomated PV quantification from 3D ultrasound (3DUS) is time intensive, limiting its incorporation into clinical care. We devised a novel convolutional neural network (CNN) pipeline for fully automated placenta segmentation from 3DUS images, exploring the association between the calculated PV and SGA.

METHODS

Volumes of 3DUS obtained from singleton pregnancies at 11-14 weeks' gestation were automatically segmented by our CNN pipeline trained and tested on 99/25 images, combining two 2D and one 3D models with downsampling/upsampling architecture. The PVs derived from the automated segmentations (PV_CNN ) were used to train multivariable logistic-regression classifiers for SGA10/SGA5. The test performance for predicting SGA was compared to PVs obtained via the semiautomated VOCAL (GE-Healthcare) method (PV_VOCAL ).

RESULTS

We included 442 subjects with 37 (8.4%) and 18 (4.1%) SGA10/SGA5 infants, respectively. Our segmentation pipeline achieved a mean Dice score of 0.88 on an independent test-set. Adjusted models including PV_CNN or PV_VOCAL were similarly predictive of SGA10 (area under curve [AUC]: PV_CNN  = 0.780, PV_VOCAL  = 0.768). The addition of PV_CNN to a clinical model without any PV included (AUC = 0.725) yielded statistically significant improvement in AUC (P < .05); whereas PV_VOCAL did not (P = .105). Moreover, when predicting SGA5, including the PV_CNN (0.897) brought statistically significant improvement over both the clinical model (0.839, P = .015) and the PV_VOCAL model (0.870, P = .039).

CONCLUSIONS

First trimester PV measurements derived from our CNN segmentation pipeline are significantly associated with future SGA. This fully automated tool enables the incorporation of including placental volumetric biometry into the bedside clinical evaluation as part of a multivariable prediction model for risk stratification and patient counseling.

The Ability of Ultrasound Sonography (USG) to Detect Intrauterine Growth Restriction (IUGR) in the Third Trimester of Pregnancy With the Gold Standard of IUGR (Parameters by USG Hadlock) as a Diagnostic Criterion

Objective

To investigate the diagnostic accuracy of the placental thickness measured by ultrasound sonography test (USG) in detecting intrauterine growth restriction (IUGR) babies in the third trimester of pregnancy, keeping IUGR (by parameters using Hadlock) as the gold standard.

Methods and materials

This cross-sectional study was conducted at the radiology department of KRL Hospital from August 5, 2020, to October 25, 2021. Informed written consent was also obtained from each patient, and the hospital's ethical committee approved the study. Three hundred and sixty-two (N=362) pregnant women patients knowing of their last menstrual period, age group 20-35 years, BMI usual, and 24 weeks gestation were included. The patient's complete history was taken by clinical examination and then ultrasound was carried out to measure the placental thickness. At 24, 32, and 36 weeks, the thickness of the placenta was assessed. The Hadlock method was used to compute the predicted fetal weight by measuring biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL) on the GC Logiq P/6 three-dimensional machine (GE, Tampa, FL). SPSS v 23 (IBM Corp., Armonk, NY) was used to calculate the mean and standard deviation from the collected data.

Results

A total of 362 patients who presented in the radiology department for antenatal ultrasound in the third trimester were recruited in our study. The mean age was 27.26 ± 4.21 years (20-35 years). In our study, the mean placenta thickness at 24 gestation weeks was 24.55 ± 0.79 mm, at 32 gestation weeks was 31.84 ± 1.34 mm, and at 36 gestation weeks was 35.54 ± 2.78. Thus, ultrasound's sensitivity, specificity, positive predictive value, and negative predictive value to determine IUGR by placental thickness was 86.30%, 86.70%, 75%, and 92%, respectively. The diagnostic accuracy of ultrasound incorrectly estimating low placental thickness was 86.40%.

Conclusion

Between 24 and 36 weeks of pregnancy, placental thickness rises almost linearly. As a result, measuring placental thickness and other factors is critical for estimating fetal age, particularly in the late second and early third trimesters, when the exact duration of pregnancy is uncertain. Placentas that were less than 29 mm thick at 32 weeks and 31 mm thick at 36 weeks were related to higher morbidity, lower Apgar scores, and more nursery admissions.

Placental functional assessment and its relationship to adverse pregnancy outcome: comparison of intravoxel incoherent motion (IVIM) MRI, T2-relaxation time, and umbilical artery Doppler ultrasound

BACKGROUND

Early identification of placental insufficiency can lead to appropriate treatment selections and can improve neonates' outcomes. Possible contributions of magnetic resonance imaging (MRI) have been suggested.

PURPOSE

To evaluate the prognostic capabilities of placental intravoxel incoherent motion (IVIM) parameters and T2-relaxation time, and their correlation with fetal growth and adverse outcomes, comparing umbilical artery (UmA) pulsatility index (PI).

MATERIAL AND METHODS

A total of 68 singleton pregnancies at 24-40 weeks of gestation underwent placental MRI and were reviewed retrospectively. UmA-PI was measured using Doppler ultrasound by obstetricians. IVIM parameters (Dfast, Dslow, and f) were calculated with a Bayesian model fitting. First, the associations between gestational age (GA) with placental IVIM parameters, T2-relaxation time, and placental thickness (PT) were evaluated. Second, IVIM parameters, T2 value (Z-score), PT (Z-score), and UmA-PI (Z-score) were compared between ( 1) those delivering small for gestational age (SGA) and appropriate for gestational age (AGA) neonates, ( 2) emergency cesarean section (ECS), and non-ECS, and ( 3) preterm birth and full-term birth.

RESULTS

Low birth weight was observed in 15/68 cases (22%). GA was significantly associated only with T2-relaxation time and PT. SGA was significantly associated with T2 value (Z-score), f, and UmA-PI (Z-score). In the ECS groups, T2 value (Z-score), f, and Dfast were significantly lower than those in non-ECS groups. All IVIM parameters and T2 values (Z-score) showed significantly lower scores in the preterm birth group.

CONCLUSION

Placental f and T2 value (Z-score) had significant associations with low birth weight and clinical adverse outcomes and could be potential imaging biomarkers of placental insufficiency.

Ultrasonographic placental thickness versus fetal outcome: A prospective study in Southern India

Background:

Variations in placental thickness are associated with increased perinatal morbidity and mortality. However, only very few studies have been established on the correlation between placental thickness with birth outcomes. This study correlated placental thickness in 2^nd and 3^rd trimesters with neonatal outcome, maternal weight gain, and body mass index (BMI).

Methods:

A total of 116 patients aged between 20 to 50 years with singleton pregnancy and regular menstrual history (and sure about their last menstrual period) were included. Placental thickness was measured at 24 and 36 weeks by ultrasound and was divided into three groups: Group A (normal placenta), Group B (thin placenta), and Group C (thick placenta); and correlated with neonatal outcome, maternal weight gain, and BMI.

Results:

Out of the 116 pregnant women, 55 (47.4%) were primigravida and 61 (52.6%) were multigravida. Six patients (3.6%) delivered pre-term before 36 weeks. In the 2^nd and 3^rd trimesters, most cases had normal placental thickness (Group A; 93.1% and 92.7%), followed by thin placenta (Group B; 5.2% and 7.3%) and thick placenta (Group C; 1.7% and 0), respectively. Two patients with thin placenta had neonatal death. A significant positive correlation was found between birth weight and placental thickness (at 24 weeks; 0.516^r, P<0.00001 and at 36 weeks; 0.669^r, P<0.00001) and maternal weight gain and birth weight (0.563^r, P<0.00001).

Conclusion:

Placental thickness on ultrasonography demonstrated well the correlation between birth weight in 2^nd and 3^rd trimesters and increased incidence of antenatal and postpartum complications resulting from thin placenta.

Inter- and Intraobserver Agreement in First Trimester Ultrasound Evaluation of Placental Biometry

OBJECTIVE

The aim of this study was to assess the clinical applicability of a new analytical software program by determining the inter- and intraobserver agreement for 2D placental biometry and three-dimensional (3D) placental volume (PV) in the first trimester.

METHODS

A prospective study of 25 singleton pregnancies between 11 and 14 weeks was conducted. 3D datasets were captured, and PV was estimated using the Phillips QLAB GI3DQ ultrasound quantification software. The basal plate (BP), chorionic plate (CP), placental thickness (PT), and the free uterine surface (FUS) area not occupied by placenta were considered for 2D biometry evaluation. Each variable was measured in 2 orthogonal planes with mean values used for the analysis. Intra- and interobserver agreement was evaluated.

RESULTS

Intraobserver agreement for both 2D and 3D measurements was high, particularly for the PV and PT (interclass correlation coefficient [ICC] 0.989 [95% confidence interval (CI) 0.97-0.99] and ICC 0.936 [95% CI 0.86-0.97], respectively). Interobserver agreement was good for the PV (ICC 0.963 [95% CI 0.91-0.98]), PT (ICC 0.822 [95% CI 0.63-0.91]), and CP (ICC 0.708 [95% CI 0.44-0.86]), but moderate for BP and FUS.

CONCLUSIONS

PV, PT, and CP are reproducible measurements to evaluate first trimester placental biometry. Further research is needed to assess the clinical utility of these variables as predictors of poor obstetric outcomes.

Amniodrainage-Induced Circulatory Dysfunction in Women Treated for Twin-To-Twin Transfusion Syndrome

Twin-to-twin transfusion syndrome (TTTS) in monochorionic-diamniotic twin pregnancies usually requires fetoscopic laser ablation (FLA) followed by amniodrainage (AD). Perioperative maternal hemodynamic changes and hemodilution have been observed. Little is known about the underlying pathophysiology. We aimed to evaluate the impact of high volume amniodrainage on intrauterine pressure, placental thickness and maternal blood characteristics. A total of 18 cases of TTTS were included in this prospective pilot study. All patients were treated with FLA and subsequent AD. Intrauterine pressure and placental thickness were assessed before, during and after amniodrainage. Maternal hemoglobin, hematocrit and serum albumin were measured at admission and 24 h after the intervention. Amniodrainage led to a decrease in mean intrauterine pressure (from 30.1 ± 8.1 mmHg to 17.6 ± 3.6 mmHg (p < 0.001)) and an increase in mean placental thickness (from 16.8 ± 6.4 mm to 31.83 ± 8.64 mm (p < 0.001)). There was a positive correlation between changes in placental thickness and the amount of amniodrainage during intervention (Pearson's Rho 0.73; p = 0.001). Hematocrit decreased from 33.4 ± 3.8 (%) to 28.4 ± 3.5 (%), i.e., an increase in relative blood volume by 18 ± 10.2% (p < 0.001). Albumin decreased from 37.9 ± 0.9 g/L to 30.7 ± 2.2 g/L, i.e., an increase in relative plasma volume by 24 ± 8.1% (p < 0.001). Amniodrainage leads to uterine decompression, increased placental thickness and subsequent maternal hemodilution. We propose the term "amniodrainage-induced circulatory dysfunction" for these specific maternal hemodynamic changes in the treatment of twin-to-twin transfusion syndrome.

Minimally interactive placenta segmentation from three-dimensional ultrasound images

Purpose: Placental size in early pregnancy has been associated with important clinical outcomes, including fetal growth. However, extraction of placental size from three-dimensional ultrasound (3DUS) requires time-consuming interactive segmentation methods and is prone to user variability. We propose a semiautomated segmentation technique that requires minimal user input to robustly measure placental volume from 3DUS images. Approach: For semiautomated segmentation, a single, central 2D slice was manually annotated to initialize an automated multi-atlas label fusion (MALF) algorithm. The dataset consisted of 47 3DUS volumes obtained at 11 to 14 weeks in singleton pregnancies (28 anterior and 19 posterior). Twenty-six of these subjects were imaged twice within the same session. Dice overlap and surface distance were used to quantify the automated segmentation accuracy compared to expert manual segmentations. The mean placental volume measurements obtained by our method and VOCAL (virtual organ computer-aided analysis), a leading commercial semiautomated method, were compared to the manual reference set. The test-retest reliability was also assessed. Results: The overlap between our automated segmentation and manual (mean Dice: 0.824 ± 0.061 , median: 0.831) was within the range reported by other methods requiring extensive manual input. The average surface distance was 1.66 ± 0.96    mm . The correlation coefficient between test-retest volumes was r = 0.88 , and the intraclass correlation was ICC ( 1 ) = 0.86 . Conclusions: MALF is a promising method that can allow accurate and reliable segmentation of the placenta with minimal user interaction. Further refinement of this technique may allow for placental biometry to be incorporated into clinical pregnancy surveillance.

Placental ARFI elastography and biometry evaluation in bitches

Placental rigidity and biometry of twelve pregnant bitches were evaluated using B-mode and Acoustic Radiation Force Impulse (ARFI) ultrasonography, performed once daily, from day 15 of gestation until parturition. Specific software (Virtual Touch Tissue Quantification® VTTQ and Virtual Touch Tissue Imaging Quantification® VTTIQ) were used. Values for results for variables were correlated and regression models related to gestational day were used to make evaluations. Maternal-fetal placental thickness increased to day 63 (P < 0.0001; R² = 0.91); maternal placental thickness increased until day 40 (P = 0.0340; R² = 0.54); and fetal placental thickness increased to day 50 (P < 0.0001; R² = 0.83) of gestation. Shear wave velocity (SWV) of the dorsal (P < 0.0010) was greater than lateral, which in turn was greater (P = 0.020) than the ventral area. The SWV of the dorsal area as determined using VTTQ, decreased from day 21-35 and increased to day 56 of gestation (P = 0.0291; R² = 0.4021); lateral SWV decreased from day 24-45 and increased until the time of parturition (P < 0.001; R² = 0.6055). The SWV of the dorsal area, as determined using VTTIQ, decreased from day 21-43 and then increased to day 60 of gestation (P = 0.0016; R² = 0.5075); and ventral area SWV increased from day 21-23 and decreased until the time of parturition (P < 0.001; R² = 0.8055). Placental alterations reflect structural and biochemical gestational adaptations and can become useful techniques for obstetrics.

The Placental Basis of Fetal Growth Restriction

Placental dysfunction is a major contributing factor to fetal growth restriction. Placenta-mediated fetal growth restriction occurs through chronic fetal hypoxia owing to poor placental perfusion through a variety of mechanisms. Maternal vascular malperfusion is the most common placental disease contributing to fetal growth restriction; however, the role of rare placental diseases should not be overlooked. Although the features of maternal vascular malperfusion are identifiable on placental pathology, antepartum diagnostic methods are evolving. Placental imaging and uterine artery Doppler, used in conjunction with angiogenic growth factors (specifically placenta growth factor and soluble fms-like tyrosine kinase-1), play an increasingly important role.

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.

In vivo textural and morphometric analysis of placental development in healthy & growth-restricted pregnancies using magnetic resonance imaging

BACKGROUND

The objective of this study was to characterize structural changes in the healthy in vivo placenta by applying morphometric and textural analysis using magnetic resonance imaging (MRI), and to explore features that may be able to distinguish placental insufficiency in fetal growth restriction (FGR).

METHODS

Women with healthy pregnancies or pregnancies complicated by FGR underwent MRI between 20 and 40 weeks gestation. Measures of placental morphometry (volume, elongation, depth) and digital texture (voxel-wise geometric and signal-intensity analysis) were calculated from T2W MR images.

RESULTS

We studied 66 pregnant women (32 healthy controls, 34 FGR); during the study period, placentas undergo significant increases in size; signal intensity remains relatively constant, however there is increasing variation in spatial arrangements, suggestive of progressive microstructural heterogeneity. In FGR, placental size is smaller, with great homogeneity of signal intensity and spatial arrangements.

CONCLUSION

We report quantitative textural and morphometric changes in the in vivo placenta in healthy controls over the second half of pregnancy. These MRI features demonstrate important differences in placental development in the setting of placental insufficiency that relate to onset and severity of FGR, as well as neonatal outcome.

Small for gestational age infants and the association with placental and umbilical cord morphometry: a digital imaging study

Introduction: Individual placental and umbilical cord morphometry have been previously identified to have an association with fetal growth. This study aims to identify which of the morphometric measurements in combination are associated with pregnancies with small for gestational age (SGA) infants using digital imaging of the delivered placenta.Material and methods: This study examined 1005 placentas from consecutively delivered singleton pregnancies in a tertiary center. Standardized images of each placenta were taken. Placental weight and thickness; umbilical cord length and diameter were measured on gross examination. Distance from the placental cord insertion site to placental margin, length and breadth of the placenta and placental chorionic surface area were measured digitally using ImageJ software. Logistic regression models and area under the curve (AUC) were used to identify the best subset of morphometric measurements to classify infants as SGA (<10th centile).Results: Overall, 141 (14%) infants were SGA. The morphometric measurements at delivery most strongly associated with the classification of infants as SGA were placental weight (AUC = 0.806) and placental surface area (AUC = 0.749). Of the potential antenatal morphometric measurements, umbilical cord diameters, both placental (AUC = 0.644) and fetal end (AUC = 0.629) were most strongly associated with SGA. A logistic regression model with maternal age, smoking status, current history of preeclampsia, umbilical cord length, placental weight, birthweight-to-placental weight ratio and umbilical cord diameter (placental end) had a sensitivity of 53% and a false-positive rate of 2% (AUC = 0.945) for the classification of infants as SGA.Conclusion: Placental and umbilical cord morphometry measured at delivery are different between SGA and non-SGA infants. Further studies are warranted to investigate the feasibility and accuracy of ultrasound to measure placental and umbilical cord morphometry during pregnancy.

Role of Ultrasonographic Placental Thickness in Prediction of Fetal Outcome: A Prospective Indian Study

BACKGROUND INFORMATION

Placenta is the connecting organ between the mother and the fetus. It supplies oxygen and all the necessary elements for the growth and development of the fetus. In normal pregnancy, the growth of the placenta remains concordant with the growth of the fetus. The sonographic assessment of placenta can give information about the nutritional status of the fetus. It is known that normal placental thickness approximately equals gestational age. It is historically documented that placental weight is one-fifth of the fetal weight and abnormally thin or thick placenta is associated with increased incidence of perinatal morbidity and mortality. However, there are very few studies correlating placental thickness with Neonatal outcome.

OBJECTIVES

To correlate ultrasonographic placental thickness at 32 and 36 weeks pregnancy with neonatal outcome. To propose placental thickness as a simple test for prediction of neonatal outcome.

METHODS

Placental thickness at 32 and 36 weeks was measured by ultrasound, in 130 pregnant mothers with confirmed dates and uncomplicated singleton pregnancy. Placental thickness was categorized as normal (10th-95th percentile), thin (<10th percentile) and thick (>95th percentile) at each stage and was correlated with birth weight and neonatal outcome.

RESULTS

Neonatal outcome was good in women with normal placental thickness (10th-95th percentile) at 32 and 36 weeks and was compromised in women with thin (<10th percentile) and thick (>95th percentile) placentae.

CONCLUSION

Placental thickness at 32 and 36 weeks corresponds well with gestational age and is a good prognostic factor in assessing neonatal outcome. Therefore, placental thickness should be measured in addition to biometric parameters in antenatal women undergoing ultrasound.

Mode of conception does not affect fetal or placental growth parameters or ratios in early gestation or at delivery

PURPOSE

Ratio of fetal weight to placenta size varies by mode of conception (fertility treatments utilized) in animals. Our objective was to assess whether fertility treatments also affect these ratios in humans.

METHODS

In this retrospective study, we assessed two cohorts: (a) early gestation cohort, women with singleton pregnancies who underwent first trimester vaginal ultrasound and (b) delivered cohort, women who delivered a live-born, singleton infant with placenta disposition to pathology. Crown rump length (CRL) and estimated placental volume (EPV) were calculated from first trimester ultrasound images using a validated computation. Infant birth weight (BW), pregnancy data, placental weight (PW), and placental histopathology were collected. Fetal growth-to-placental weight ratios (CRL/EPV; BW/PW) and placentas were compared by mode of conception. Linear regression was used to adjust for confounding variables.

RESULTS

Two thousand one hundred seventy patients were included in the early gestation cohort and 1443 in the delivered cohort. Of the early gestation cohort (a), 85.4% were spontaneous conceptions, 5.9% Non-IVF Fertility (NIFT), and 8.7% IVF. In the delivered cohort (b), 92.4% were spontaneous, 2.1% NIFT, and 80 5.5% IVF. There were no significant differences between fetal growth-to-placental weight parameters, ratios, and neonatal birth measurements based on mode of conception. Placenta accreta was significantly higher in the patients receiving fertility treatments (1.2 versus 3.6%, p < 0.05).

CONCLUSIONS

Mode of conception does not appear to influence fetal growth-to-placental weight ratios throughout gestation. In addition, findings in animal models may not always translate into human studies of infertility treatment outcomes.

In vivo placental MRI shape and textural features predict fetal growth restriction and postnatal outcome

PURPOSE

To investigate the ability of three-dimensional (3D) MRI placental shape and textural features to predict fetal growth restriction (FGR) and birth weight (BW) for both healthy and FGR fetuses.

MATERIALS AND METHODS

We recruited two groups of pregnant volunteers between 18 and 39 weeks of gestation; 46 healthy subjects and 34 FGR. Both groups underwent fetal MR imaging on a 1.5 Tesla GE scanner using an eight-channel receiver coil. We acquired T2-weighted images on either the coronal or the axial plane to obtain MR volumes with a slice thickness of either 4 or 8 mm covering the full placenta. Placental shape features (volume, thickness, elongation) were combined with textural features; first order textural features (mean, variance, kurtosis, and skewness of placental gray levels), as well as, textural features computed on the gray level co-occurrence and run-length matrices characterizing placental homogeneity, symmetry, and coarseness. The features were used in two machine learning frameworks to predict FGR and BW.

RESULTS

The proposed machine-learning based method using shape and textural features identified FGR pregnancies with 86% accuracy, 77% precision and 86% recall. BW estimations were 0.3 ± 13.4% (mean percentage error ± standard error) for healthy fetuses and -2.6 ± 15.9% for FGR.

CONCLUSION

The proposed FGR identification and BW estimation methods using in utero placental shape and textural features computed on 3D MR images demonstrated high accuracy in our healthy and high-risk cohorts. Future studies to assess the evolution of each feature with regard to placental development are currently underway.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:449-458.

Placental thickness-to-estimated foetal weight ratios and small-for-gestational-age infants at delivery

This study aimed to determine the correlation between the placental thickness-to-estimated foetal weight ratio on midterm ultrasonography and small-for-gestational-age (SGA) infants. In this retrospective study, the placental thickness at the umbilical cord insertion site was measured and adjusted for foetal body weight at 18-24 weeks gestation. Investigators compared the data of women who delivered SGA infants (birth weight <10th percentile) with those of women who delivered non-SGA infants. Among the 1281 women in this study, those who delivered SGA infants were younger and less likely to be obese. Women with higher placental thickness-to-estimated foetal weight ratios delivered more SGA infants. In logistic regression analysis, a higher placental thickness-to-estimated foetal weight ratio remained associated with SGA infants. Since the placental thickness-to-estimated foetal weight ratio in midterm pregnancy was associated with infant body weight at delivery, this ratio could be an effective, adjunctive screening marker for predicting SGA status.

Mode of conception does not appear to affect placental volume in the first trimester

OBJECTIVE

To study whether infertility treatments, including IVF and non-IVF fertility treatments, are associated with diseases of placental insufficiency in early gestation. First trimester placental volumes by ultrasound and chorionic villi weight during sampling (CVS) were performed to detect differences between pregnancies conceived spontaneously versus with fertility treatments.

DESIGN

Retrospective cohort.

SETTING

Academic tertiary center.

PATIENT(S)

Women with singleton pregnancies undergoing CVS and first trimester ultrasound from April 2007 to November 2015.

INTERVENTION(S)

Estimated placental volume (EPV) was calculated from ultrasound images using a validated computation and CVS estimated tissue weight was performed using a validated visual analogue scale.

MAIN OUTCOME MEASURE(S)

Adjusted linear regression was used to compare EPV and CVS weight based on mode of conception.

RESULT(S)

A total of 1,977 spontaneous and 334 conceived with fertility treatments (133 non-IVF and 201 IVF) pregnancies were included. Significant differences in maternal age, gravidity, hypertension, and smoking status were identified. EPV and CVS weight were correlated with maternal age, gestational age, and maternal hypertension. Adjusted linear regression showed no difference in EPV in pregnancies conceived with fertility treatments versus spontaneously. The CVS weight was significantly lower in the IVF conceptions in unadjusted univariate analyses. However, after adjusted regression, this was no longer significant.

CONCLUSION(S)

Mode of conception does not appear to affect first trimester placental size. As differences in maternal age, hypertension, and smoking status differ among the groups and are correlated to placental size, it may be the underlying patient population leading to abnormal placentation and insufficiency, not the fertility treatments used.

Second-Trimester 3-Dimensional Placental Sonography as a Predictor of Small-for-Gestational-Age Birth Weight

OBJECTIVES

We previously reported the association between first-trimester 3-dimensional (3D) placental measurements and small-for-gestational-age (SGA) neonates. In this study, we sought to determine whether second-trimester measurements further contribute to the antenatal detection of SGA and preeclampsia.

METHODS

We prospectively collected 3D sonographic volume sets and uterine artery pulsatility indices of singleton pregnancies at 18 to 24 weeks. Placental volume, placental quotient (placental volume/gestational age), mean placental diameter and chorionic diameter, placental morphologic index (mean placental diameter/placental quotient), placental chorionic index (mean chorionic diameter/placental quotient), and placental growth (volume per week) were assessed and evaluated as predictors of SGA and preeclampsia as a composite and alone.

RESULTS

Of 373 pregnancies, the composite outcome occurred in 67 (18.0%): 36 (9.7%) manifested SGA alone; 27 (7.2%) developed preeclampsia alone, and 4 (1.1%) developed both. The placental volume, placental quotient, mean placental diameter, mean chorionic diameter, and volume per week were significantly smaller, whereas the placental morphologic index and chorionic index were significantly larger in pregnancies with the composite outcome (P < .01). Further analyses revealed that the significant associations with placental parameters were limited to the SGA outcome. Each placental measure remained significantly associated with SGA after adjusting for confounders. The mean uterine artery pulsatility index was not associated with either outcome. Placental parameters were moderately predictive of SGA, with adjusted areas under the curve ranging from 0.72 to 0.76. Sensitivity for detection of SGA ranged from 32.5% to 45.0%, with positive predictive values ranging from 17.3% to 22.7%.

CONCLUSIONS

Second-trimester 3D placental measurements can identify pregnancies at risk of SGA. However, there appears to be no significant improvement compared to those obtained in the first trimester.

Placental Volumetry by 2-D Sonography with a New Mathematical Formula: Prospective Study on the Shell of a Spherical Sector Model

The aim of this study was to determine the utility of a new mathematical model in volumetric assessment of the placenta using 2-D ultrasound. Placental volumetry was performed in a prospective cross-sectional survey by virtual organ computer-aided analysis (VOCAL) with the help of a shell-off method in 346 uncomplicated pregnancies according to STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines. Furthermore, placental thickness, length and height were measured with the 2-D technique to estimate placental volume based on the mathematical formula for the volume of "the shell of the spherical sector." Fetal size was also assessed by 2-D sonography. The placental volumes measured by 2-D and 3-D techniques had a correlation of 0.86. In the first trimester, the correlation was 0.82, and later during pregnancy, it was 0.86. Placental volumetry using "the circle-shaped shell of the spherical sector" mathematical model with 2-D ultrasound technique may be introduced into everyday practice to screen for placental volume deviations associated with adverse pregnancy outcome.

First-trimester placental ultrasound and maternal serum markers as predictors of small-for-gestational-age infants

OBJECTIVE

The objective of the study was to combine early, direct assessment of the placenta with indirect markers of placental development to identify pregnancies at greatest risk of delivering small-for-gestational age infants (SGA10).

STUDY DESIGN

We prospectively collected 3-dimensional ultrasound volume sets, uterine artery pulsatility index, and maternal serum of singleton pregnancies at 11-14 weeks. Placental volume (PV), quotient (placental quotient [PQ] = PV/gestational age), mean placental diameter (MPD) and chorionic diameters, and the placental morphology index (PMI = MPD/PQ and adjusts the lateral placental dimensions for quotient) were measured offline. Maternal serum was assayed for placental growth factor and placental protein-13. These variables were evaluated as predictors of SGA10.

RESULTS

Of the 578 pregnancies included in the study, 56 (9.7%) delivered SGA10. SGA10 pregnancies had a significantly smaller PV, PQ, MPD, and mean placental diameter and higher PMI compared with normal pregnancies (P < .001 for each). Each placental measure remained significantly associated with SGA10 after adjusting for confounders and significantly improved the performance of the model using clinical variables alone (P < .04 for each) with adjusted areas under the curve ranging from 0.71 to 0.74. Uterine artery pulsatility index did not remain significantly associated with SGA10 after adjusting for confounders (P = .06). Placental growth factor was significantly lower in SGA10 pregnancies (P = .02) and remained significant in adjusted models but failed to significantly improve the predictive performance of the models as measured by area under the curve (P > .3). Placental protein-13 was not associated with SGA10 (P = .99).

CONCLUSION

Direct assessment of placental size and shape with 3-dimensional ultrasound can serve as the foundation upon which to build a multivariable model for the early prediction of SGA.

Macrosomia has its roots in early placental development

INTRODUCTION

We sought to determine if early placental size, as measured by 3-dimensional ultrasonography, is associated with an increased risk of delivering a macrosomic or large-for-gestational age (LGA) infant.

METHODS

We prospectively collected 3-dimensional ultrasound volume sets of singleton pregnancies at 11-14 weeks and 18-24 weeks. Birth weights were collected from the medical records. After delivery, the ultrasound volume set were used to measure the placental volume (PV) and placental quotient (PQ = PV/gestational age), as well as the mean placental and chorionic diameters (MPD and MCD, respectively). Placental measures were analyzed as predictors of macrosomia (birth weight ≥4000 g) and LGA (birth weight ≥90th percentile).

RESULTS

The 578 pregnancies with first trimester volumes included 44 (7.6%) macrosomic and 43 (7.4%) LGA infants. 373 subjects also had second trimester volumes available. A higher PV and PQ were both significantly associated with macrosomia and LGA in both the first and second trimesters. Second trimester MPD was significantly associated with both outcomes as well, while second trimester MCD was only associated with LGA. The above associations remained significant after adjusting for maternal demographic variables such as race, ethnicity, age and diabetes. Adjusted models yielded moderate prediction of macrosomia and LGA (AUC: 0.71-0.77).

CONCLUSIONS

Sonographic measurement of the early placenta can identify pregnancies at greater risk of macrosomia and LGA. Macrosomia and LGA are already determined in part by early placental growth and development.

Placental hyperinflation and the risk of adverse perinatal outcome

OBJECTIVES

To determine the pathological basis and clinical associations of excessively thick placentae observed at second-trimester ultrasound examination.

METHODS

In a retrospective cohort of 19 singleton high-risk second-trimester pregnancies noted to have a placental length-to-maximum thickness ratio ≤ 2.0, maximum sonographic placental thickness was correlated with clinical outcome, maximum placental thickness after delivery and placental pathological findings. Results were compared with those of an intermediate group of 21 high-risk pregnancies with normal placental dimensions and a control group of 18 low-risk pregnancies also with normal placental dimensions. Increased maximum placental thickness (> 28 mm) and abnormal placental deflation following delivery (pathology - sonography difference in maximum placental thickness < -2 mm) were defined by the upper and lower quartile values, respectively, in the control group.

RESULTS

The study group exhibited significantly more adverse outcomes and gross pathological placental features compared with both intermediate and control groups. Despite increased sonographic maximum placental thickness in the study group (median, 55 (range, 40-75) mm compared with both the intermediate group (median, 27 (range, 22-41) mm, P < 0.0001) and the control group (median 26 (range, 23-36) mm, P < 0.0001)), all three groups had similar maximal placental thickness following delivery (study group: median, 24 (range, 10-50) mm vs intermediate group: median, 27 (range, 15-40) mm, P = 0.82 and vs control group: median, 28.5 (range, 18-44), P = 0.42). Pathology-sonography difference in maximum placental thickness in the study group (median, -30 (range, -42 to 0) mm) was significantly greater than that in either the intermediate (median, -2 (range, -11 to 9) mm, P < 0.0001) or the control (median, 1.5 (range, -10 to 18) mm, P < 0.0001) group and was significantly associated with abnormal development of the gas-exchanging placental villi (distal villous hypoplasia) (P = 0.0001).

CONCLUSIONS

Increased second-trimester sonographic maximum placental thickness represents a pathological finding associated with severe adverse perinatal outcome. This observation is due to overinflation of the intervillous space by maternal blood rather than to adaptive formation of functional placental tissue.