Fetal imaging and therapy for CDH-Current status

In congenital diaphragmatic hernia (CDH), herniation of the abdominal organs into the fetal chest causes pulmonary hypoplasia and pulmonary hypertension, the main causes of neonatal mortality. As antenatal ultrasound screening improves, the risk of postnatal death can now be better predicted, allowing for the identification of fetuses that might most benefit from a prenatal intervention. Fetoscopic tracheal occlusion is being evaluated in a large international randomized controlled trial. We present the antenatal imaging approaches that can help identify fetuses that might benefit from antenatal therapy, and review the evolution of fetal surgery for CDH to date.

Growth Patterns of Fetal Lung Volumes in Healthy Fetuses and Fetuses With Isolated Left-Sided Congenital Diaphragmatic Hernia

OBJECTIVES

To evaluate fetal lung growth using 3-dimensional sonography in healthy fetuses and those with congenital diaphragmatic hernia (CDH).

METHODS

Right and total lung volumes were serially evaluated by 3-dimensional sonography in 66 healthy fetuses and 52 fetuses with left-sided CDH between 20 and 37 weeks' menstrual age. Functions fitted to these parameters were compared for 2 groups: (1) healthy versus those with CDH; and (2) fetuses with CHD who survived versus those who died.

RESULTS

Fetal right and total lung volumes as well as fetal observed-to-expected right and total lung volume ratios were significantly lower in fetuses with CDH than healthy fetuses (P< .001) and in those fetuses with CDH who died (P< .001). The observed-to-expected right and total lung volume ratios did not vary with menstrual age in healthy fetuses or in those with CDH (independent of outcome).

CONCLUSIONS

Lung volume rates were lower in fetuses with left-sided CDH compared to healthy fetuses, as well as in fetuses with CDH who died compared to those who survived. The observed-to-expected right and total lung volume ratios were relatively constant throughout menstrual age in fetuses with left-sided CDH, suggesting that the origin of their lung growth abnormalities occurred before 20 weeks and did not progress. The observed-to-expected ratios may be useful in predicting the outcome in fetuses with CDH independent of menstrual age.

A preterm pig model of lung immaturity and spontaneous infant respiratory distress syndrome

Respiratory distress syndrome (RDS) and bronchopulmonary dysplasia remain the leading causes of preterm infant morbidity, mortality, and lifelong disability. Research to improve outcomes requires translational large animal models for RDS. Preterm pigs delivered by caesarian section at gestation days (GD) 98, 100, 102, and 104 were provided 24 h of neonatal intensive care, monitoring (pulse oximetry, blood gases, serum biomarkers, radiography), and nutritional support, with or without intubation and mechanical ventilation (MV; pressure control ventilation with volume guarantee). Spontaneous development of RDS and mortality without MV are inversely related with GD at delivery and correspond with inadequacy of tidal volume and gas exchange. GD 98 and 100 pigs have consolidated lungs, immature alveolar architecture, and minimal surfactant protein-B expression, and MV is essential at GD 98. Although GD 102 pigs had some alveoli lined by pneumocytes and surfactant was released in response to MV, blood gases and radiography revealed limited recruitment 1-2 h after delivery, and mortality at 24 h was 66% (35/53) with supplemental oxygen provided by a mask and 69% (9/13) with bubble continuous positive airway pressure (8-9 cmH2O). The lungs at GD 104 had higher densities of thin-walled alveoli that secreted surfactant, and MV was not essential. Between GD 98 and 102, preterm pigs have ventilation inadequacies and risks of RDS that mimic those of preterm infants born during the saccular phase of lung development, are compatible with standards of neonatal intensive care, and are alternative to fetal nonhuman primates and lambs.

Early fetoscopic tracheal occlusion for extremely severe pulmonary hypoplasia in isolated congenital diaphragmatic hernia: preliminary results

OBJECTIVE

To evaluate the effect of early fetoscopic tracheal occlusion (FETO) (22-24 weeks' gestation) on pulmonary response and neonatal survival in cases of extremely severe isolated congenital diaphragmatic hernia (CDH).

METHODS

This was a multicenter study involving fetuses with extremely severe CDH (lung-to-head ratio < 0.70, liver herniation into the thoracic cavity and no other detectable anomalies). Between August 2010 and December 2011, eight fetuses underwent early FETO. Data were compared with nine fetuses that underwent standard FETO and 10 without fetoscopic procedure from January 2006 to July 2010. FETO was performed under maternal epidural anesthesia, supplemented with fetal intramuscular anesthesia. Fetal lung size and vascularity were evaluated by ultrasound before and every 2 weeks after FETO. Postnatal therapy was equivalent for both treated fetuses and controls. Primary outcome was infant survival to 180 days and secondary outcome was fetal pulmonary response.

RESULTS

Maternal and fetal demographic characteristics and obstetric complications were similar in the three groups (P > 0.05). Infant survival rate was significantly higher in the early FETO group (62.5%) compared with the standard group (11.1%) and with controls (0%) (P < 0.01). Early FETO resulted in a significant improvement in fetal lung size and pulmonary vascularity when compared with standard FETO (P < 0.01).

CONCLUSIONS

Early FETO may improve infant survival by further increases of lung size and pulmonary vascularity in cases with extremely severe pulmonary hypoplasia in isolated CDH. This study supports formal testing of the hypothesis with a randomized controlled trial.

Prediction of mortality and the need for neonatal extracorporeal membrane oxygenation therapy by 3-dimensional sonography and magnetic resonance imaging in fetuses with congenital diaphragmatic hernias

OBJECTIVES

To compare different rotation angles for assessment of fetal lung volume by 3-dimensional (3D) sonography with magnetic resonance imaging (MRI) regarding prediction of mortality and the need for neonatal extracorporeal membrane oxygenation (ECMO) therapy in fetuses with congenital diaphragmatic hernias.

METHODS

One hundred patients with fetal congenital diaphragmatic hernias between 22 and 39 weeks' gestation were examined by 3D sonography and MRI. Sonographic contralateral fetal lung volumes were assessed by the rotational technique (virtual organ computer-aided analysis) at 3 different rotation angles: 6°, 15°, and 30°. The MRI fetal lung volumes were calculated based on multiplanar T2-weighted MRI. To eliminate the influence of gestational age, the observed to expected contralateral fetal lung volume on sonography and the observed to expected fetal lung volume on MRI were calculated. Receiver operating characteristic (ROC) curves were calculated for the statistical prediction of survival and need for ECMO therapy by the observed to expected contralateral fetal lung volume (sonography) and observed to expected fetal lung volume (MRI).

RESULTS

One hundred cases were assessed for survival and 89 for ECMO necessity (11 neonates were not eligible for ECMO). For prediction of postpartum survival and ECMO necessity, the areas under the ROC curves (AUCs) showed very similar results for MRI and 3D sonography: observed to expected fetal lung volume by MRI, 0.819 (95% confidence interval, 0.730-0.909) and 0.835 (0.748-0.922), respectively; 6° sonography, 0.765 (0.647-0.883) and 0.820 (0.734-0.905); 15° sonography, 0.784 (0.672-0.896) and 0.811 (0.719-0.903); and 30° sonography, 0.732 (0.609-0.855) and 0.772 (0.671-0.872). Comparisons between the AUCs revealed no statistical differences.

CONCLUSIONS

We have shown the good prognostic value of 3D sonography in fetuses with congenital diaphragmatic hernias compared with MRI, particularly when using small rotation angles. Therefore, it can be an appropriate diagnostic tool when counseling patients for congenital diaphragmatic hernias.

Quantitative lung index, contralateral lung area, or lung-to-head ratio to predict the neonatal outcome in isolated congenital diaphragmatic hernia?

OBJECTIVES

To estimate the accuracy of the quantitative lung index and contralateral lung area for prediction of the neonatal outcome in isolated congenital diaphragmatic hernia in comparison to other available prediction models.

METHODS

Between January 2004 and December 2010, 108 fetuses with isolated (82 left-sided and 26 right-sided) congenital diaphragmatic hernia were prospectively evaluated. The quantitative lung index and observed-to-expected contralateral lung area were measured and compared to the neonatal survival rate and severe postnatal pulmonary arterial hypertension, along with the lung-to-head ratio, observed-to-expected lung-to-head ratio, and observed-to-expected total lung volume.

RESULTS

Overall neonatal mortality was 64.8% (70 of 108). Severe pulmonary arterial hypertension was diagnosed in 68 (63.0%) of the cases, which was associated with neonatal death (P < .001). Both the quantitative lung index and observed-to-expected contralateral lung area were significantly associated with neonatal survival and pulmonary arterial hypertension (P < .001), with accuracy to predict survival of 70.9% and 70.0%, respectively, and accuracy to predict hypertension of 78.7% and 72.0%; however, they were both less accurate than the observed-to-expected total lung volume (83.3% and 86.1%; P < .01). The lung-to-head ratio (73.1% and 78.7%) and observed-to-expected lung-to-head ratio (75.9% and 72.2%; P > .05) had similar accuracy as the quantitative lung index and observed-to-expected contralateral lung area.

CONCLUSIONS

The observed-to-expected total lung volume is the most accurate predictor of the neonatal outcome in cases of isolated congenital diaphragmatic hernia. Both the quantitative lung index and observed-to-expected contralateral lung area, albeit reasonably accurate, do not produce the same level of accuracy and render similar results as the lung-to-head ratio and observed-to-expected lung-to-head ratio.

Fetal pulmonary response after fetoscopic tracheal occlusion for severe isolated congenital diaphragmatic hernia

OBJECTIVE

To estimate the response in lung growth and vascularity after fetal endoscopic tracheal occlusion for severe congenital diaphragmatic hernia in the prediction of neonatal survival.

METHODS

Between January 2006 and December 2010, fetal lung parameters (observed-to-expected lung-to-head ratio; observed-to-expected lung volume; and contralateral lung vascularization index) were evaluated before fetal tracheal occlusion and were evaluated longitudinally every 2 weeks in 72 fetuses with severe isolated congenital diaphragmatic hernia. Thirty-five fetuses underwent fetal endoscopic tracheal occlusion and 37 cases did not.

RESULTS

Survival rate was significantly higher in the fetal endoscopic tracheal occlusion group (54.3%) than in the no fetal endoscopic tracheal occlusion group (5.4%, P<.01). Fetal endoscopic tracheal occlusion resulted in a significant improvement in fetal lung size and pulmonary vascularity when compared with fetuses that did not go to the fetal intervention (increase of the observed-to-expected lung-to-head ratio, observed-to-expected total lung volume, and contralateral pulmonary vascularization index 56.2% compared with 0.3%, 37.9% compared with 0.1%, and 98.6% compared with 0.0%, respectively; P<.01). Receiver operating characteristic curves indicated that the observed-to-expected total fetal lung volume was the single best predictor of neonatal survival before fetal endoscopic tracheal occlusion (cutoff 0.23, area under the curve [AUC] 0.88, relative risk 5.3, 95% confidence interval [CI] 1.4-19.7). However, the contralateral lung vascularization index at 4 weeks after fetal endoscopic tracheal occlusion was more accurate in the prediction of neonatal outcome (cutoff 24.0%, AUC 0.98, relative risk 9.9, 95% CI 1.5-66.9) with the combination of observed-to-expected lung volumes and contralateral lung vascularization index at 4 weeks being the best predictor of outcome (AUC 0.98, relative risk 16.6, 95% CI 2.5-112.3).

CONCLUSION

Fetal endoscopic tracheal occlusion improves survival rate by increasing the lung size and pulmonary vascularity in fetuses with severe congenital diaphragmatic hernia. The pulmonary response after fetal endoscopic tracheal occlusion can be used to predict neonatal survival.

Prediction and probability of neonatal outcome in isolated congenital diaphragmatic hernia using multiple ultrasound parameters

OBJECTIVES

To evaluate the accuracy and probabilities of different fetal ultrasound parameters to predict neonatal outcome in isolated congenital diaphragmatic hernia (CDH).

METHODS

Between January 2004 and December 2010, we evaluated prospectively 108 fetuses with isolated CDH (82 left-sided and 26 right-sided). The following parameters were evaluated: gestational age at diagnosis, side of the diaphragmatic defect, presence of polyhydramnios, presence of liver herniated into the fetal thorax (liver-up), lung-to-head ratio (LHR) and observed/expected LHR (o/e-LHR), observed/expected contralateral and total fetal lung volume (o/e-ContFLV and o/e-TotFLV) ratios, ultrasonographic fetal lung volume/fetal weight ratio (US-FLW), observed/expected contralateral and main pulmonary artery diameter (o/e-ContPA and o/e-MPA) ratios and the contralateral vascularization index (Cont-VI). The outcomes were neonatal death and severe postnatal pulmonary arterial hypertension (PAH).

RESULTS

Neonatal mortality was 64.8% (70/108). Severe PAH was diagnosed in 68 (63.0%) cases, of which 63 died neonatally (92.6%) (P < 0.001). Gestational age at diagnosis, side of the defect and polyhydramnios were not associated with poor outcome (P > 0.05). LHR, o/e-LHR, liver-up, o/e-ContFLV, o/e-TotFLV, US-FLW, o/e-ContPA, o/e-MPA and Cont-VI were associated with both neonatal death and severe postnatal PAH (P < 0.001). Receiver-operating characteristics curves indicated that measuring total lung volumes (o/e-TotFLV and US-FLW) was more accurate than was considering only the contralateral lung sizes (LHR, o/e-LHR and o/e-ContFLV; P < 0.05), and Cont-VI was the most accurate ultrasound parameter to predict neonatal death and severe PAH (P < 0.001).

CONCLUSIONS

Evaluating total lung volumes is more accurate than is measuring only the contralateral lung size. Evaluating pulmonary vascularization (Cont-VI) is the most accurate predictor of neonatal outcome. Estimating the probability of survival and severe PAH allows classification of cases according to prognosis.

Current advances in prenatal imaging of congenital diaphragmatic [corrected] hernia

Congenital diaphragmatic hernia, despite advances in therapy, remains a complex condition with significant morbidity and mortality. The etiology of the disorder is still incompletely understood, though the pulmonary hypoplasia and pulmonary hypertension that develop secondarily must be overcome to improve survival. Prenatal US and fetal MRI have helped in the development of a greater understanding of this disease. Also with these modalities, measurement techniques have been developed in an attempt to provide prognosticators for the development of pulmonary hypoplasia and pulmonary hypertension. There is a broad range of approaches for performing these measurements, and variability among imaging centers is noted. Despite inconsistent approaches, these techniques have become the foundation for counseling and prenatal and postnatal therapy. It is hoped that with further research with prenatal US and fetal MRI and the development of innovative medical and surgical therapies that the morbidity and mortality of children with congenital diaphragmatic hernias can be significantly reduced.

Assessment of lung volume by 3-dimensional sonography and magnetic resonance imaging in fetuses with congenital diaphragmatic hernias

OBJECTIVES

The purpose of this study was to evaluate the influence of different rotation angles in assessment of the contralateral lung volume by 3-dimensional (3D) sonography in comparison to magnetic resonance imaging (MRI) in fetuses with congenital diaphragmatic hernias.

METHODS

A total of 126 measurements by 3D sonography and MRI were conducted in 81 patients between 18 and 39 weeks' gestation. The 3D sonographic volumes of the contralateral fetal lung were calculated by the rotational technique (virtual organ computer-aided analysis) with rotation angles of 6°, 15°, and 30°. Transverse multiplanar T2-weighted MRI was performed for the MRI measurements. To compare the accuracy of 3D sonographic volumetry using different rotation angles, MRI assessment was taken as the reference method, and percentage errors and limits of agreement were calculated for each angle.

RESULTS

Three-dimensional sonographic volume measurements showed a high correlation with MRI (6° angle, R(2) = 0.86; 15° angle, R(2) = 0.78; 30° angle, R(2) = 0.68). The mean percentage error showed no systematic error. With regard to random error, the 6° step had significantly lower values than the larger angles 30° step (R = 0.472) and the narrowest limits of agreement.

CONCLUSIONS

Especially when using a small rotation angle, assessment of the contralateral fetal lung volume by 3D sonography in congenital diaphragmatic hernias is a reliable alternative to MRI.

Influence of different rotation angles in assessment of lung volumes by 3-dimensional sonography in comparison to magnetic resonance imaging in healthy fetuses

OBJECTIVES

Three-dimensional (3D) sonographic volumetry is established in gynecology and obstetrics. Assessment of the fetal lung volume by magnetic resonance imaging (MRI) in congenital diaphragmatic hernias has become a routine examination. In vitro studies have shown a good correlation between 3D sonographic measurements and MRI. The aim of this study was to compare the lung volumes of healthy fetuses assessed by 3D sonography to MRI measurements and to investigate the impact of different rotation angles.

METHODS

A total of 126 fetuses between 20 and 40 weeks' gestation were measured by 3D sonography, and 27 of them were also assessed by MRI. The sonographic volumes were calculated by the rotational technique (virtual organ computer-aided analysis) with rotation angles of 6° and 30°. To evaluate the accuracy of 3D sonographic volumetry, percentage error and absolute percentage error values were calculated using MRI volumes as reference points. Formulas to calculate total, right, and left fetal lung volumes according to gestational age and biometric parameters were derived by stepwise regression analysis.

RESULTS

Three-dimensional sonographic volumetry showed a high correlation compared to MRI (6° angle, R(2) = 0.971; 30° angle, R(2) = 0.917) with no systematic error for the 6° angle. Moreover, using the 6° rotation angle, the median absolute percentage error was significantly lower compared to the 30° angle (P < .001). The new formulas to calculate total lung volume in healthy fetuses only included gestational age and no biometric parameters (R(2) = 0.853).

CONCLUSIONS

Three-dimensional sonographic volumetry of lung volumes in healthy fetuses showed a good correlation with MRI. We recommend using an angle of 6° because it assessed the lung volume more accurately. The specifically designed equations help estimate lung volumes in healthy fetuses.

Congenital diaphragmatic hernia: review of the literature in reflection of unresolved dilemmas

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a rare but clinically and scientifically challenging condition. The introduction of ultrasound has enabled early prenatal detection and consequently, hope of early therapeutic intervention.

AIM

We undertook the task to review the recent developments in understanding the pathology of CDH as well as the history and current management strategies to aid perinatologists in consultations with parents of CDH-affected foetuses.

STUDY DESIGN

A Medline search was undertaken of all reports and reviews published between 1980 and 2008 using MeSH search terms 'diaphragmatic hernia', 'congenital' and 'newborn'.

RESULTS

The true incidence of CDH is still difficult to estimate because of the high incidence of hidden mortality of CDH. Complete case ascertainment also poses difficulties in assessment of the impact of new therapeutic modalities on overall survival. Recent improvements in prenatal detection are a milestone in affording time for re-assessments and parental counselling. The true benefit of antenatal therapy is circumscribed and should be offered only in selected cases of isolated severe CDH as defined by existing guidelines. Postnatal intensive respiratory supportive therapy and innovative surgical techniques within specialized tertiary centres has had a major impact on survival of babies with CDH.

CONCLUSION

The high survival of 'selected cases' that are live births and benefit from optimal care will be difficult to improve by antenatal interventions. The multidisciplinary approach to basic research and randomized clinical trials will further define the best approach to the foetus and neonate with CDH.