Ultrasonographic measurement of the abdominal circumference in fetuses with congenital diaphragmatic hernia

Accuracy of Estimated Fetal Weight Assessment in Fetuses with Congenital Diaphragmatic Hernia-Is the Hadlock Formula a Reliable Tool?

Objectives: Congenital diaphragmatic hernia (CDH) is defined as organ protrusion from the abdominal to the thoracic cavity. The Hadlock formula is the most commonly used tool for calculating estimated fetal weight (EFW). The anatomical nature of CDH usually leads to underestimation of the abdominal circumference, resulting in underestimation of fetal weight. Accurate weight estimation is essential before birth for counselling, preparation before surgery and ECMO. The research is made to compare the accuracy of Hadlock's formula and Faschingbauer's formula for fetal weight estimation in CDH fetuses population. Methods: In our study, we investigated differences between EFW and actual birthweight in 42 fetuses with CDH as compared to 80 healthy matched controls. EFW was calculated using the Hadlock formula and a recently introduced formula described by Faschingbauer et al., which was tailored for fetuses with CDH. Additionally, both of the formulas were adjusted for the interval between the ultrasound and delivery for both of the groups. Results: The majority of hernias were left-sided (92.8% vs. 7.2%). EFW adjusted for the interval between the ultrasound and delivery had the highest correlation with the actual birthweight in both, study group and controls. We compared the results for both tools and found the Hadlock formula to predict birthweight in CDH children with a 7.8 ± 5.5% error as compared to 7.9 ± 6.5% error for the Faschingbauer's formula. Conclusions: The Hadlock formula adjusted for the interval between the ultrasound and delivery is a more precise method of calculating EFW in fetuses with CDH. Routine biometry scan using Hadlock's formula remains reliable for predicting birthweight.

Accuracy of estimated fetal weight assessment in fetuses with congenital diaphragmatic hernia

BACKGROUND

Congenital diaphragmatic hernia is a congenital anomaly in which fetal abdominal organs herniate into the thoracic cavity through a diaphragmatic defect, which can impede fetal lung development. Standard formulas for estimated fetal weight include measurement of fetal abdominal circumference, which may be inaccurate in fetuses with congenital diaphragmatic hernia because of displacement of abdominal contents into the thorax.

OBJECTIVES

This study aimed to assess the accuracy of standard estimated fetal weight assessment in fetuses with congenital diaphragmatic hernia by comparing prenatal assessment of fetal weight with actual birthweight.

STUDY DESIGN

A retrospective cohort study of fetuses diagnosed with congenital diaphragmatic hernia was performed at a single center from 2012 to 2018. Fetuses with multiple anomalies or confirmed chromosome abnormalities were excluded. Estimated fetal weight was calculated using the Hadlock formula. Published estimates of fetal growth rate were used to establish a projected estimated fetal weight at birth from the final growth ultrasound, and the percentage difference between projected estimated fetal weight at birth and actual birthweight was calculated. A Wilcoxan rank-sum test was used to examine the difference between projected estimated fetal weight and birthweight.

RESULTS

We had complete data for 77 fetuses with congenital diaphragmatic hernia. The majority (76.6%, 55 of 77) had left-sided congenital diaphragmatic hernia. The median [interquartile range] projected estimated fetal weight was similar to median birthweight, at 3177 g [2691-3568] and 3180 g [2630-3500], respectively, which did not represent a statistically significant difference between projected estimated fetal weight and birthweight (P = .66). The median absolute percentage difference between projected birthweight and actual birthweight was 6.3% [3.2-7.0]. Estimated fetal weight was overall underestimated in a minority of cases (44.2%, 34 of 77).

CONCLUSION

In fetuses with a congenital diaphragmatic hernia, standard measurements of fetal estimated fetal weight show accuracy that is at least comparable with previously established margins of error for ultrasound assessment of fetal weight. Standard estimated fetal weight assessment remains an appropriate method of estimating fetal weight in fetuses with congenital diaphragmatic hernia.

Prenatal prediction of survival in isolated diaphragmatic hernia using observed to expected total fetal lung volume determined by magnetic resonance imaging based on either gestational age or fetal body volume

OBJECTIVES

To compare the predictive value of the prenatal observed to expected (o/e) lung volume as measured by fetal magnetic resonance imaging (MRI), based on an algorithm using either the gestational age or fetal body volume (FBV), for neonatal survival of fetuses with isolated congenital diaphragmatic hernia (CDH).

METHODS

We included 53 fetuses with a prenatal diagnosis of isolated CDH, 26 without and 27 with prenatal tracheal occlusion, who were assessed by fetal MRI, liveborn after 32 weeks, and in whom follow-up until discharge from the neonatal care unit was available. Measurements of lung volumes were expressed as a percentage of the appropriate mean (o/e total fetal lung volume (TFLV) x 100) either for gestational age or for FBV. Measurements of FBV were expressed as a percentage of the appropriate mean (o/e FBV x 100) for gestation. Fetuses with prenatal intervention were all assessed > or = 24 h after balloon removal. Regression analysis was used to examine the effect on postnatal survival of either o/e TFLV based on gestational age or based on FBV, gestation at delivery, side of CDH, intrathoracic position of the liver and prenatal intervention. Receiver-operating characteristics (ROC) curves were constructed for the prediction of survival by o/e TFLV based on gestational age and o/e TFLV based on FBV, for all fetuses, as well as for those with o/e FBV between 90 and 110% and those with values beyond that range. A power calculation for the number of fetuses needed to show a difference between the ROC curves was performed.

RESULTS

Regression analysis demonstrated that o/e TFLV based on gestational age and on FBV were the only independent predictors of postnatal survival. The area under the ROC curve for prediction of postnatal survival from the o/e TFLV based on gestational age was 0.811, and for that based on FBV it was 0.868 (P < 0.001 for both). For fetuses with o/e FBV between 90 and 110%, and those with values < 90% and > 110%, the area for measurements based on gestational age was 0.895 and 0.733, respectively; when based on FBV it was 0.906 and 0.833 (P < 0.01 for all). A minimum of 273 patients would be needed to provide a probability of 90% of detecting a difference between the areas under both ROC curves.

CONCLUSIONS

In fetuses with isolated CDH, lung volume as measured by fetal MRI was significantly correlated with survival. Prediction tended to be better by o/e TFLV based on FBV rather than gestational age. The difference in the prediction of survival between o/e TFLV based on FBV or gestational age was dependent on fetal biometry.

Fetal pulmonary artery diameter measurements as a predictor of morbidity in antenatally diagnosed congenital diaphragmatic hernia: a prospective study

OBJECTIVE

The objective of the study was to examine the size and growth of fetal pulmonary artery diameters in congenital diaphragmatic hernia and assess their correlation with postnatal survival and morbidity outcomes.

STUDY DESIGN

Prospective antenatal echocardiographic examination of fetal branch pulmonary arteries were correlated with postnatal survival and respiratory morbidity in cases of congenital diaphragmatic hernia. Receiver operator curves were developed to assess their utilization as predictors of respiratory morbidity and survival.

RESULTS

Twenty-one cases were diagnosed antenatally over 3 years. Fifteen subjects survived postnatally. The ipsilateral fetal branch pulmonary artery diameter was smaller throughout gestation in left-sided congenital diaphragmatic hernia (P = .008). The small left pulmonary diameter did not correlate with survival but correlated strongly with morbidity outcomes. Progressive ipsilateral fetal pulmonary artery hypoplasia was demonstrated throughout gestation in subjects who died or had severe morbidity.

CONCLUSION

Fetal pulmonary artery diameter measurements correlate with respiratory morbidity in postnatal congenital diaphragmatic hernia and may assist with prediction of outcome. Survival has improved, possibly because of improved postnatal management of congenital diaphragmatic hernia, limiting this measurement in assessing survival.

Fetal Relative Lung Volume: Quantification by Using Prenatal MR Imaging Lung Volumetry

PURPOSE

To retrospectively determine a biometric algorithm for calculating relative lung volume in fetuses with normal lungs and of a wide range of gestational ages by using proved independent variables and to retrospectively investigate the use of this algorithm in fetuses with pulmonary hypoplasia.

MATERIALS AND METHODS

Total lung volume (TLV) was measured by using planimetry on single-shot rapid acquisition with relaxation enhancement magnetic resonance (MR) images obtained in 91 fetuses with ultrasonographically (US) normal chests and 28 fetuses with US-determined pulmonary hypoplasia. All fetuses were aged between 18 and 38 weeks gestation. Analysis of covariance was used to identify parameters that were not different between the fetuses with US-determined normal and those with US-determined abnormal chests, and these variables were used to construct an algorithm for calculating predicted lung volume. The relative lung volume-that is, the observed lung volume expressed as a percentage of the predicted lung volume-was then calculated in fetuses with pulmonary hypoplasia.

RESULTS

There was no significant difference in mean maternal or gestational age between the two fetus groups. Stepwise regression analysis was used to generate the following equation for predicting fetal lung volume on the basis of independent biometric indexes, with a correlation coefficient of 0.93: TLV = (0.52 . LV) + (0.33 . BD) - (0.06 . FL) - 13.7, with TLV and liver volume (LV) in milliliters and biparietal diameter (BD) and femoral length (FL) in centimeters. In the fetuses with normal chests, relative lung volume varied between 51% and 134%. In the fetuses with pulmonary hypoplasia, relative lung volume varied between 6% and 70%.

CONCLUSION

The predicted lung volume in fetuses of a wide range of gestational ages can be calculated with a high degree of accuracy, enabling prenatal MR imaging lung volumetry in which relative lung volume is used to quantify fetal pulmonary hypoplasia.