Ultrasound versus Clinical Examination to Estimate Fetal Weight at Term

The Impact on Birth Outcomes of Sonographic Fetal Weight Estimation in Neonatal Macrosomia

OBJECTIVE

 Our objective was to examine the association between sonographic estimated fetal weight (EFW) and obstetrical and neonatal outcomes in women with neonatal macrosomia.

STUDY DESIGN

 This study, conducted at a tertiary university-affiliated hospital from 2017 to 2021, compared obstetrical and neonatal outcomes between two groups of women who delivered macrosomic newborns (actual birthweight ≥ 4,000 g): (1) those with EFW ≥ 3,800 g (suspected impending macrosomia) and (2) those with EFW < 3,800 g (unsuspected impending macrosomia).

RESULTS

 During the study period, 854 women with neonatal macrosomia attempted vaginal delivery. Only 9.2% had a sonographic EFW ≥ 4,000 g. Among women with EFW ≥ 3,800 g (n = 317) compared with EFW < 3,800 g (n = 537), the cesarean delivery (CD) rate was higher (17.0 vs. 10.5%, p = 0.004) and the operative delivery rate was lower (3.2 vs. 0.6%, p = 0.015). Among primiparous women, the CD rate was higher among those with EFW ≥ 3,800 versus <3,800 g (37.3 vs. 23.2%, p = 0.033). EFW ≥3,800 g was associated with CD, regardless of predelivery body mass index, parity, diabetes mellitus, maximal fetal weight at previous deliveries, actual birthweight, and labor induction (p = 0.014). EFW ≥ 3,800 g and diabetes mellitus were independent predictors of CD. Among women with EFW ≥3,800 g and diabetes mellitus, the risk of CD was double that of those without diabetes and with EFW ≥ 3,800 g (31.4% vs. 15.2%, p = 0.02), although their actual birthweights were similar. Obstetrical and neonatal outcomes were similar between those with sonographic EFW ≥ 3,800 and < 3,800 g.

CONCLUSION

 Larger EFW increased CD risk among pregnancies with actual neonatal macrosomia. Antenatally suspected macrosomia might alter labor management due to concerns for potential complications, especially when associated with primiparity, diabetes mellitus, or maternal obesity. The increase in the CD rate did not show an association with improved maternal and neonatal outcomes.

KEY POINTS

· Antenatally suspected macrosomia might alter labor management due to concerns about complications.. · Larger EFW increased cesarean delivery risk among pregnancies with actual neonatal macrosomia.. · The increase in the cesarean delivery rate was not associated with improved outcomes..

Accuracy of Estimated Fetal Weight by Ultrasound Versus Leopold Maneuver

ABSTRACT

Estimated fetal weight (EFW) is frequently used for clinical decision-making in obstetrics. The goals of this study were to determine the accuracy of EFW assessments by Leopold and ultrasound and to investigate any associations with maternal characteristics. Postgraduate years 1 and 2 obstetrics and gynecology resident physicians from Harbor-UCLA Medical Center from 2014 to 2020 performed EFW assessments on 10 preterm (<37 weeks' gestational age) fetuses by ultrasound biometry and 10 full-term (≥37 weeks' gestational age) fetuses by ultrasound biometry and Leopold maneuver. Assessments were included if the patients delivered within 2 weeks of the assessments. One thousand six hundred ninety-seven EFW assessments on 1183 patients performed by 33 residents were analyzed; 72.6% of sonographic full-term EFWs, 69% of Leopold full-term EFWs, and 61.5% of sonographic preterm EFWs were within 10% of the neonatal birth weight (BW). The lowest estimation error in our study occurred when actual BW was 3600 to 3700 g. After adjusting for BW, residents were found to have lower accuracy when the mother had a higher body mass index (BMI) for full-term estimation methods (Leopold and ultrasound, β = 0.13 and 0.12, P = 0.001 and 0.002, respectively). Maternal BMI was not related to estimation error for preterm fetuses ( β = 0.01, P = 0.75). Clinical and sonographic EFW assessments performed by obstetrics and gynecology junior residents are within 10% of neonatal BW much of the time. In our cohort, they tended to overestimate EFWs of lower-BW infants and underestimate EFWs of higher-BW infants. Accuracy of full-term EFW assessments seems to decrease with increasing maternal BMI.

Are Junior Residents Accurate at Predicting Fetal Weight? An Analysis of Junior Residents' Performance of Estimated Fetal Weight Using Ultrasound and Leopold's Maneuver

Background

Performing accurate estimated fetal weights (EFWs) is a critical skill developed in obstetrics residency training. Resident physicians are often the first to perform EFWs on obstetric patients when they enter care. Evaluating residents' accuracy in performing EFWs is crucial for assessing their achievement in residency training milestones and providing patient care.

Methods

As part of an educational initiative program between 2014 and 2020, postgraduate year 1 (PGY1) and postgraduate year 2 (PGY2) residents performed EFW measurements on 10 term (>37w0d) patients using ultrasound and Leopold's maneuver and 10 preterm (>24w0d and <37w0d) patients using ultrasound. Clinical characteristics, mode of delivery, and actual birthweights (BWs) were recorded for each patient. The accuracy of these estimates was evaluated using mixed-effect regression models.

Results

Thirty-three residents, 1127 deliveries, and 1790 EFW measurements were evaluated. Overall, the percentage of residents with estimations within 10% of actual BW went up in PGY2 for Leopold's and ultrasound term births, but not for preterm ultrasound births. Maternal body mass index and actual BW were associated with absolute percentage estimation error. After adjusting for these variables, there was a statistically significant decrease in error between PGY1 and PGY2 for Leopold's method in term births; ultrasound (term and preterm) showed more modest reductions in error during PGY2.

Discussion

Resident physicians have accurate estimates of EFWs early in their training, beginning in their first year of residency by both Leopold's maneuver and ultrasound. Furthermore, PGY2 residents performed better than PGY1 residents for Leopold's method.

Factors Affecting Clinical over and Underestimation of Fetal Weight-A Retrospective Cohort

Clinical estimation of fetal weight is an integral component of obstetric care that might dictate the timing and mode of delivery. Inaccurate fetal weight estimation might result in unnecessary interventions or in underestimating potential risks, resulting in inappropriate intrapartum care. This retrospective study assessed factors associated with under- or overestimation of birthweight and evaluated the obstetric implications. It included singleton births ≥24 w with clinically estimated fetal weight (EFW) up to 1 week before delivery, during 2014−2020. Estimates >±10% of the actual birthweight were considered inaccurate and categorized as overestimation (>10% heavier than the actual birthweight) or underestimation (>10% smaller than the birthweight). Multivariable logistic regression was performed to reveal factors associated with inaccurate EFW. Maternal characteristics and obstetric outcomes were compared. The primary outcomes for the overestimation group were the neonatal composite adverse outcome, induction of labor and cesarean delivery rates. The primary outcomes for the underestimation group were rates of shoulder dystocia, 3rd- or 4th-degree perineal lacerations, and failed vacuum extraction. Among 38,615 EFW, 5172 (13.4%) were underestimated, 6695 (17.3%) were overestimated and 27,648 (69.3%) accurate. Multivariable logistic regression found increasing gestational age as an independent risk-factor for underestimation (odds ratio (OR) 1.15 for every additional week, 95% confidence interval (CI) 1.12−1.2). Major factors independently associated with overestimation were nulliparity (OR 1.95, CI 1.76−2.16), maternal obesity (OR 1.52, CI 1.33−1.74), smoking (OR 1.6, CI 1.33−1.93), and oligohydramnios (OR 1.92, CI 1.47−2.5). Underestimation was an independent risk-factor for shoulder dystocia (OR 1.61, CI 1.05−2.46) and 3rd- or 4th-degree perineal lacerations (OR 1.59, CI 1.05−2.43). Overestimation was an independent risk-factor for neonatal composite adverse outcome (OR 1.15, CI 1.02−1.3), induced labor (OR 1.30, CI 1.21−1.40) and cesarean delivery (OR 1.59, CI 1.41−1.79). Clinicians should be aware of factors and adverse obstetric implications associated with over- or underestimation of birthweight.

Prospective verification of sonographic fetal weight estimators among term parturients in Uganda

BACKGROUND

Accuracy of fetal weight estimation by ultrasound is essential in making decisions on the time and mode of delivery. There are many proposed formulas for fetal weight estimation such as Hadlock 1, Hadlock 2, Hadlock 3, Hadlock 4 and Shepard. What best applies to the Ugandan population is not known since no verification of any of the formulas has been done before. The primary aim of this study was to determine the accuracy of sonographic estimation of fetal weight using five most commonly used formulas, and analyze formula variations for different weight ranges.

METHODS

This was a hospital based prospective cohort study at Mulago National Referral Hospital, Kampala, Uganda. A total of 356 pregnant women who consented and were within 3 days of birth were enrolled. Prenatal ultrasound fetal weight determined by measuring the biparietal diameter, head circumference, abdominal circumference, femoral length, and then was compared with actual birth weight.

RESULTS

The overall accuracy of Hadlock 1, Hadlock 2, Hadlock 3, Hadlock 4 and Shepard formula were 66.9, 73.3, 77.3, 78.4 and 69.7% respectively. All Hadlocks showed significant mean difference between weight estimates and actual birth weight (p < 0.01) whereas Shepard formula did not [p - 0.2], when no stratification of fetal weights was done. However, all Hadlocks showed a none significant (p-values > 0.05) mean difference between weight estimates and actual birth weight when the actual birth weight was ≥4000.0 g. Shepard weight estimates showed a none significant mean difference when actual birth weight was < 4000 g. Bland-Altman graphs also showed a better agreement of weight estimated by Shepard formula and actual birth weights.

CONCLUSION

All the five formulas were accurate at estimating actual birth weights within 10% accuracy. However, this accuracy varied with the fetal birth weight. Shepard was more accurate in estimating actual birth weights < 4000 g whereas all Hadlocks were more accurate when the actual birthweight was ≥4000 g.

Error-corrected estimation of a diagnostic accuracy index of a biomarker against a continuous gold standard

This article concerns evaluating the effectiveness of a continuous diagnostic biomarker against a continuous gold standard that is measured with error. Extending the work of Obuchowski (2005, 2016), Wu et al (2016) suggested an accuracy index and proposed an estimator for the index with error-prone standard when the reliability coefficient is known. Combining with additional measurements (without measurement errors) on the continuous gold standard collected from some subjects, this article proposes two adaptive estimators of the accuracy index when the reliability coefficient is unknown, and further establish the consistency and asymptotic normality of these estimators. Simulation studies are conducted to compare various estimators. Data from an intervention trial on glycemic control among children with type 1 diabetes are used to illustrate the proposed methods.

Influence of Foetal Macrosomia on the Neonatal and Maternal Birth Outcome

Introduction Foetal macrosomia is associated with various obstetrical complications and is a common reason for inductions and primary or secondary Caesarean sections. The objective of this study is the generation of descriptive data on the mode of delivery and on maternal and foetal complications in the case of foetal macrosomia. The causes and consequences of foetal macrosomia as well as the rate of shoulder dystocia are examined in relation to the severity of the macrosomia.

Patients The study investigated all singleton births ≥ 37 + 0 weeks of pregnancy with a birth weight ≥ 4000 g at the Charité University Medicine Berlin (Campus Mitte 2001 – 2017, Campus Virchow Klinikum 2014 – 2017).

Results 2277 consecutive newborns (birth weight 4000 – 4499 g [88%], 4500 – 4999 g [11%], ≥ 5000 g [1%]) were included. Maternal obesity and gestational diabetes were more common in the case of newborns weighing ≥ 4500 g than newborns weighing 4000 – 4499 g (p = 0.001 and p < 0.001). Women with newborns ≥ 5000 g were more often ≥ 40 years of age (p = 0.020) and multipara (p = 0.025). The mode of delivery was spontaneous in 60% of cases, vaginal-surgical in 9%, per primary section in 14% and per secondary section in 17%. With a birth weight ≥ 4500 g, a vaginal delivery was more rare (p < 0.001) and the rate of secondary sections was increased (p = 0.011). Women with newborns ≥ 4500 g suffered increased blood loss more frequently (p = 0.029). There was no significant difference with regard to the rate of episiotomies or serious birth injuries. Shoulder dystocia occurred more frequently at a birth weight of ≥ 4500 g (5 vs. 0.9%, p = 0.000). Perinatal acidosis occurred in 2% of newborns without significant differences between the groups. Newborns ≥ 4500 g were transferred to neonatology more frequently (p < 0.001).

Conclusion An increased birth weight is associated with an increased maternal risk and an increased rate of primary and secondary sections as well as shoulder dystocia; no differences in the perinatal outcome between newborns with a birth weight of 4000 – 4499 g and ≥ 4500 g were seen. In our collective, a comparably low incidence of shoulder dystocia was seen. In the literature, the frequency is indicated with a large range (1.9 – 10% at 4000 – 4499 g, 2.5 – 20% at 4500 – 5000 g and 10 – 20% at ≥ 5000 g). One possible cause for the low rate could be the equally low prevalence of gestational diabetes in our collective. A risk stratification of the pregnant women (e.g. avoidance of vacuum extraction, taking gestational diabetes into account during delivery planning) is crucial. If macrosomia is presumed, it is recommended that delivery take place at a perinatal centre in the presence of a specialist physician, due to the increased incidence of foetal and maternal complications.

Fetal weight estimation at term - ultrasound versus clinical examination with Leopold's manoeuvres: a prospective blinded observational study

BACKGROUND

Fetal weight estimation is of key importance in the decision-making process for obstetric planning and management. The literature is inconsistent on the accuracy of measurements with either ultrasound or clinical examination, known as Leopold's manoeuvres, shortly before term. Maternal BMI is a confounding factor because it is associated with both the fetal weight and the accuracy of fetal weight estimation. The aim of our study was to compare the accuracy of fetal weight estimation performed with ultrasound and with clinical examination with respect to BMI.

METHODS

In this prospective blinded observational study we investigated the accuracy of clinical examination as compared to ultrasound measurement in fetal weight estimation, taking the actual birth weight as the gold standard. In a cohort of all consecutive patients who presented in our department from January 2016 to May 2017 to register for delivery at ≥37 weeks, examination was done by ultrasound and Leopold's manoeuvres to estimate fetal weight. All examiners (midwives and physicians) had about the same level of professional experience. The primary aim was to compare overall absolute error, overall absolute percent error, absolute percent error > 10% and absolute percent error > 20% for weight estimation by ultrasound and by means of Leopold's manoeuvres versus the actual birth weight as the given gold standard, namely separately for normal weight and for overweight pregnant women.

RESULTS

Five hundred forty-three patients were included in the data analysis. The accuracy of fetal weight estimation was significantly better with ultrasound than with Leopold's manoeuvres in all absolute error calculations made in overweight pregnant women. For all error calculations performed in normal weight pregnant women, no statistically significant difference was seen in the accuracy of fetal weight estimation between ultrasound and Leopold's manoeuvres.

CONCLUSIONS

Data from our prospective blinded observational study show a significantly better accuracy of ultrasound for fetal weight estimation in overweight pregnant women only as compared to Leopold's manoeuvres with a significant difference in absolute error. We did not observe significantly better accuracy of ultrasound as compared to Leopold's manoeuvres in normal weight women. Further research is needed to analyse the situation in normal weight women.