Assessment of fetal growth using the ratio of the transverse cerebellar diameter to abdominal circumference

Role of Transcerebellar Diameter and Transcerebellar Diameter/Abdominal Circumference Ratio in Assessing Fetal Growth and Diagnosing Intrauterine Growth Restriction

Background In obstetrics, accurately determining gestational age (GA) is a critical aspect of managing pregnancy and evaluating fetal growth and development. Intrauterine growth restriction (IUGR) is characterized by the failure of the fetus to reach its potential growth. Early detection of IUGR is crucial for optimal obstetric care to reduce fetal complications and neonatal morbidity and mortality. The purpose of the current research is to determine the role of transcerebellar diameter (TCD) and the TCD/abdominal circumference (AC) ratio in assessing fetal growth and diagnosing IUGR. Methods In the sample, there were 600 expectant mothers with GA exceeding 28 weeks. We measured TCD and AC and then calculated the TCD/AC ratio. We used IBM SPSS Statistics for Windows, V. 22.0 (IBM Corp., Armonk, NY), for statistical analysis. The data was subjected to statistical tests, including Pearson's correlation coefficient, coefficient of determination, and tests of validity. Results The current research demonstrates a strong linear correlation between TCD and GA. Additionally, there was no notable disparity in TCD measurements between normal and IUGR fetuses with the same GA. There was an insignificant relationship between the TCD/AC ratio and GA, with a constant TCD/AC ratio in the third trimester of pregnancy in normal fetuses. The mean TCD/AC ratio was 14.72±0.89 (mean±standard deviation), and a cut-off value of 16.5 was determined to diagnose IUGR. Conclusion TCD can serve as a reliable measure for GA estimation during the third trimester in pregnant women with uncertain last menstrual period (LMP) or no dating scan and IUGR fetuses. In diagnosing IUGR, the TCD/AC ratio has demonstrated greater sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The TCD/AC ratio is a GA-independent measure that can be used to diagnose IUGR.

Determination of the Accuracy of Transcerebellar Diameter in Estimating Gestational Age in the Second and Third Trimesters of Pregnancy

Background Every antenatal woman and her treating doctor aim for a healthy newborn. In obstetrics, accurately determining the gestational age (GA) is a critical aspect of managing pregnancy and evaluating fetal growth and development. The transcerebellar diameter (TCD) is the greatest transverse measurement of the fetal cerebellum. The growth of the cerebellum is minimally affected by fluctuations in growth, making the TCD the most reliable measurement for predicting GA. The purpose of the present research is to determine the accuracy of TCD in estimating GA in the second and third trimesters of pregnancy. Materials and methods The study included 500 antenatal women at 18-40 weeks of gestation. We also measured TCD in addition to routine ultrasound parameters like biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL). We used IBM SPSS Statistics for Windows, Version 22 (Released 2013; IBM Corp., Armonk, New York, United States) for statistical analysis. The collected data was subjected to statistical tests, including Pearson's correlation coefficient and coefficient of determination. We conducted a regression analysis and used correlation coefficients to compare each ultrasound-measured parameter with the GA. Results The current research demonstrates a significant linear relationship between the TCD and GA (r = 0.9865; p = 0.0001), a strong association between BPD and GA (r = 0.9541; p = 0.0001), between HC and GA (r = 0.9613; p = 0.0001), between AC and GA (r = 0.9489; p = 0.0001), and between FL and GA (r = 0.9697; p = 0.0001). TCD showed the best correlation with GA among all the biometric parameters. TCD showed a correct assessment of GA by the last menstrual period (LMP) in 479 (95.8%) antenatal women. Conclusion The current research concludes that the TCD can be utilized as an independent measure to determine GA in the second and third trimesters of pregnancy, particularly in cases where the LMP is unknown, no dating scan has been performed in the first trimester, initial assessment taking place in the third trimester and in fetuses with variations in head shape such as dolichocephaly and brachycephaly.

Fetal Growth Restriction: Comparison of Biometric Parameters

The aim of this study was to identify growth-restricted fetuses using biometric parameters and to assess the validity and clinical value of individual ultrasound parameters and ratios, such as transcerebellar diameter/abdominal circumference (TCD/AC), head circumference/abdominal circumference (HC/AC), and femur length/abdominal circumference (FL/AC). In a retrospective single-center cross-sectional study, the biometric data of 9292 pregnancies between the 15th and 42nd weeks of gestation were acquired. Statistical analysis included descriptive data, quantile regression estimating the 10th and 90th percentiles, and multivariable analysis. We obtained clinically noticeable results in predicting small-for-gestational-age (SGA) and fetal growth restriction (FGR) fetuses at advanced weeks of gestation using the AC with a Youden index of 0.81 and 0.96, respectively. The other individual parameters and quotients were less suited to identifying cases of SGA and FGR. The multivariable analysis demonstrated the best results for identifying SGA and FGR fetuses with an area under the curve of 0.95 and 0.96, respectively. The individual ultrasound parameters were better suited to identifying SGA and FGR than the ratios. Amongst these, the AC was the most promising individual parameter, especially at advanced weeks of gestation. However, the highest accuracy was achieved with a multivariable model.

Utility of sonographic transcerebellar diameter in the assessment of gestational age in normal and intrauterine growth-retarded fetuses

Background

The fetal cerebellum has been shown to be least affected by external pressures and molding during pregnancy and therefore might provide more accurate estimation of GA.

Aims

To study the utility of transcerebellar diameter (TCD) measured by ultrasound for the detection of GA in normal and intrauterine growth-retarded (IUGR) fetuses.

Subjects and Methods

This cross-sectional study comprised 500 antenatal patients with a GA between 14 and 39 weeks and who were certain of their last menstrual periods. The TCD was measured ultrasonographically and the corresponding GA was determined. The GA was also determined with other customarily used sonographic parameters such as biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL) and compared with TCD. Data of normal pregnancy patients was used to formulate nomograms by taking the 5^th, 50^th, and 95^th percentile measurements. TCD to AC ratio was also calculated in both normal (n = 424) and IUGR pregnancies (n = 76).

Results

TCD showed significant correlation with gestational age (GA) measured by last menstrual period (LMP) as well as with GA calculated with other biometric fetal parameters. TCD also showed significant correlation with GA in normal (R² = 0.979) as well as with IUGR pregnancies (R² = 0.942). TCD to AC ratio remained fairly constant in normal pregnancies while it was increased in IUGR pregnancies.

Conclusions

TCD and TCD/AC ratio can be employed as an objective parameter to establish the GA in normal as well as IUGR pregnancy cases.

Can a Difference in Gestational Age According to Biparietal Diameter and Abdominal Circumference Predict Intrapartum Placental Abruption?

This study aimed to investigate whether a difference in gestational age according to biparietal diameter (BPD) and abdominal circumference (AC) could be a clinically useful predictor of placental abruption during the intrapartum period. This retrospective cohort study was based on singletons who were delivered after 32 + 0 weeks between July 2015 and July 2020. We only included cases with at least two antepartum sonographies available within 4 weeks of delivery (n = 2790). We divided the study population into two groups according to the presence or absence of placental abruption and compared the clinical variables. The incidence of placental abruption was 2.0% (56/2790) and was associated with an older maternal age, a higher rate of preeclampsia, and being small for the gestational age. A difference of >2 weeks in gestational age according to BPD and AC occurred at a higher rate in the placental abruption group compared to the no abruption group (>2 weeks, 21.4% (12/56) vs. 7.5% (205/2734), p < 0.001; >3 weeks, 12.5% (7/56) vs. 2.0% (56/2734), p < 0.001). Logistic regression analysis revealed that the differences of >2 weeks and >3 weeks were both independent risk factors for placental abruption (odds ratio (OR) (95% confidence interval), 2.289 (1.140-4.600) and 3.918 (1.517-9.771), respectively) after adjusting for maternal age, preeclampsia, and small for gestational age births. We identified that a difference in gestational age of >2 weeks between BPD and AC could be an independent predictor of placental abruption.

Predictive possibility of the transverse cerebellar diameter to abdominal circumference ratio for small-for-gestational-age fetus suspected as a cause of maternal placental syndromes: a retrospective cohort study

Objective: To examine whether fetal transverse cerebellar diameter (TCD) to abdominal circumference (AC) ratio can predict small-for-gestational age suspected as a cause of maternal placental syndromes (SGA-MPS).Methods: We evaluated 473 women who underwent ultrasound examinations at 24-28 weeks of gestation. A receiver operating characteristic curve was used to determine the TCD/AC ratio thresholds to predict SGA-MPS. We used multivariable logistic regression analysis to examine the association.Results: TCD/AC ratio>14.37 was associated with SGA-MPS.Conclusions: Accurate risk stratification using the TCD/AC ratio could assist in managing patients with small-for-gestational-age fetuses at risk of developing MPS-associated adverse outcomes.

Ultrasound fetal anthropometry to identify large-for-gestational-age: a meta-analysis

INTRODUCTION

Large-for-gestational-age (LGA) has been suggested to show high rates of mortality and morbidity in pregnant women and their neonates. This study was based on data from 2015 or later to determine whether ultrasound fetal anthropometry is helpful for identifying LGA.

EVIDENCE ACQUISITION

Sensitivity, specificity, positive and negative likelihood ratios (LRs), and diagnostic odds ratio (DOR) of studies published in English were summarized using bivariate diagnostic meta-analysis. Study quality was assessed using the revised Quality Assessment of Diagnostic Accuracy Studies tool. Deeks' funnel plot asymmetry test was assessed to identify publication bias.

EVIDENCE SYNTHESIS

The findings of abdominal circumference were based on a single article. Despite high specificity (0.92), anthropometric formulas showed moderate sensitivity (0.71) and DOR (26) and were categorized as providing "neither exclusion (positive LR<10) nor confirmation (negative LR>0.1)" strategy based on 28 good-quality studies in five articles. However, they were more promising than previous meta-analytic findings not limited to 2015 or later. No publication bias was identified with respect to assessment of anthropometric formulas (P=0.286).

CONCLUSIONS

Current ultrasound fetal anthropometry is not strongly helpful, but the values of anthropometric formulas provided by future ultrasound are expected especially as the secondary screening of LGA.

Fetal growth velocity and body proportion in the assessment of growth

Fetal growth restriction implies failure of a fetus to meet its growth potential and is associated with increased perinatal mortality and morbidity. Therefore, antenatal detection of fetal growth restriction is of major importance in an attempt to deliver improved clinical outcomes. The most commonly used approach towards screening for fetal growth restriction is by means of sonographic fetal weight estimation, to detect fetuses small for gestational age, defined by an estimated fetal weight <10th percentile for gestational age. However, the predictive accuracy of this approach is limited both by suboptimal detection rate (as it may overlook non-small-for-gestational-age growth-restricted fetuses) and by a high false-positive rate (as most small-for-gestational-age fetuses are not growth restricted). Here, we review 2 strategies that may improve the diagnostic accuracy of sonographic fetal biometry for fetal growth restriction. The first strategy involves serial ultrasound evaluations of fetal biometry. The information obtained through these serial assessments can be interpreted using several different approaches including fetal growth velocity, conditional percentiles, projection-based methods, and individualized growth assessment that can be viewed as mathematical techniques to quantify any decrease in estimated fetal weight percentile, a phenomenon that many care providers assess and monitor routinely in a qualitative manner. This strategy appears promising in high-risk pregnancies where it seems to improve the detection of growth-restricted fetuses at increased risk of adverse perinatal outcomes and, at the same time, decrease the risk of falsely diagnosing healthy constitutionally small-for-gestational-age fetuses as growth restricted. Further studies are needed to determine the utility of this strategy in low-risk pregnancies as well as to optimize its performance by determining the optimal timing and interval between exams. The second strategy refers to the use of fetal body proportions to classify fetuses as either symmetric or asymmetric using 1 of several ratios; these include the head circumference to abdominal circumference ratio, transverse cerebellar diameter to abdominal circumference ratio, and femur length to abdominal circumference ratio. Although these ratios are associated with small for gestational age at birth and with adverse perinatal outcomes, their predictive accuracy is too low for clinical practice. Furthermore, these associations become questionable when other, potentially more specific measures such as umbilical artery Doppler are being used. Furthermore, these ratios are of limited use in determining the etiology underlying fetal smallness. It is possible that the use of the 2 gestational-age-independent ratios (transverse cerebellar diameter to abdominal circumference and femur length to abdominal circumference) may have a role in the detection of mild-moderate fetal growth restriction in pregnancies without adequate dating. In addition, despite their limited predictive accuracy, these ratios may become abnormal early in the course of fetal growth restriction and may therefore identify pregnancies that may benefit from closer monitoring of fetal growth.