Proposal for standardized prenatal ultrasound assessment of the fetus with congenital diaphragmatic hernia by the European reference network on rare inherited and congenital anomalies (ERNICA)

Variability in antenatal prognostication of fetal diaphragmatic hernia across the North American Fetal Therapy Network (NAFTNet)

OBJECTIVE

To evaluate variability in antenatal sonographic prognostication of congenital diaphragmatic hernia (CDH) within the North American Fetal Therapy Network (NAFTNet).

METHODS

NAFTNet centre were invited to complete a questionnaire and participate in videoconference calls, during which participants were observed while measuring lung area by ultrasound using the anteroposterior (AP) method, longest method, and trace method. Each center identified 1-2 experienced fetal medicine specialist(s) or medical imaging specialists locally to participate in the study. Practices were compared among NAFTNet centre within and without the fetal endoscopic tracheal occlusion (FETO) consortium.

RESULTS

Nineteen participants from 9 FETO center and 30 participants from 17 non-FETO center completed the survey and 31 participants were interviewed and observed while measuring sonographic lung area. All Centres measured observed-to-expected lung-to-head ratio (o/e LHR) or LHR for CDH prognostication. Image selection criteria for lung area measurement were consistent, including an axial section of the chest with clear lung borders and a 4-chamber cardiac view. Lung area measurement methods varied across NAFTNet, with most centre using longest (4/9 FETO vs. 13/29 non-FETO) or trace (3/9 FETO vs. 11/29 non-FETO) method. Centres differed in expected reference ranges for o/e LHR determination and whether the lowest, highest or average o/e LHR was utilized.

CONCLUSION

Variability in antenatal sonographic prognostication of CDH was identified across NAFTNet, indicating a need for consensus-based standardization.

Standardization and reproducibility of sonographic stomach position grades in fetuses with congenital diaphragmatic hernia

OBJECTIVES

The purpose of this study was to evaluate the reproducibility of stomach position grading in congenital diaphragmatic hernia (CDH) as proposed by Cordier et al and Basta et al after standardization of the methods at our center.

METHODS

We collected sonographic images from 23 fetuses with left-sided CDH at our center from 2010 to 2018. Nine operators (one maternal fetal medicine expert and eight sonographers) reviewed the selected images and graded the stomach position according to the methods of Cordier et al and Basta et al. We assessed the interoperator agreement with Fleiss's kappa statistics.

RESULTS

Overall agreement amongst all operators was moderate for both methods proposed by Cordier et al (k = 0.60, SE 0.07, 95% CI 0.47-0.73, P < .0001) and Basta et al (k = 0.60, SE 0.06, 95% CI 0.47-0.73, P < .0001). Interoperator agreement was moderate for grade 3 with the method by Cordier et al (k = 0.45, SE 0.09, 95% CI 0.27-0.64, P < .0001) and fair for grade 4 with the method by Basta et al (k = 0.33, SE 0.08, 95% CI 0.18-0.49 P < .0001).

CONCLUSIONS

Our study demonstrates a fair to moderate interoperator agreement of the stomach position grading methods proposed in the literature after standardization of the methods at our center. Further multicenter studies are needed to confirm our results.

Antenatal sildenafil treatment improves neonatal pulmonary hemodynamics and gas exchange in lambs with diaphragmatic hernia

OBJECTIVES

Infants with congenital diaphragmatic hernia (CDH) are predisposed to pulmonary hypertension after birth, owing to lung hypoplasia that impairs fetal pulmonary vascular development. Antenatal sildenafil treatment attenuates abnormal pulmonary vascular and alveolar development in rabbit and rodent CDH models, but whether this translates to functional improvements after birth remains unknown. We aimed to evaluate the effect of antenatal sildenafil on neonatal pulmonary hemodynamics and lung function in lambs with diaphragmatic hernia (DH).

METHODS

DH was surgically induced at approximately 80 days' gestation in 16 lamb fetuses (term in lambs is approximately 147 days). From 105 days' gestation, ewes received either sildenafil (0.21 mg/kg/h intravenously) or saline infusion until delivery (n = 8 fetuses in each group). At approximately 138 days' gestation, all lambs were instrumented and then delivered via Cesarean section. The lambs were ventilated for 120 min with continuous recording of physiological (pulmonary and carotid artery blood flow and pressure; cerebral oxygenation) and ventilatory parameters, and regular assessment of arterial blood gas tensions. Only lambs that survived until delivery and with a confirmed diaphragmatic defect at postmortem examination were included in the analysis; these comprised six DH-sildenafil lambs and six DH-saline control lambs.

RESULTS

Lung-to-body-weight ratio (0.016 ± 0.001 vs 0.013 ± 0.001; P = 0.06) and dynamic lung compliance (0.8 ± 0.2 vs 0.7 ± 0.2 mL/cmH₂ O; P = 0.72) were similar in DH-sildenafil lambs and controls. Pulmonary vascular resistance decreased following lung aeration to a greater degree in DH-sildenafil lambs, and was 4-fold lower by 120 min after cord clamping than in controls (0.6 ± 0.1 vs 2.2 ± 0.6 mmHg/(mL/min); P = 0.002). Pulmonary arterial pressure was also lower (46 ± 2 vs 59 ± 2 mmHg; P = 0.048) and pulmonary blood flow higher (25 ± 3 vs 8 ± 2 mL/min/kg; P = 0.02) in DH-sildenafil than in DH-saline lambs at 120 min. Throughout the 120-min ventilation period, the partial pressure of arterial carbon dioxide tended to be lower in DH-sildenafil lambs than in controls (63 ± 8 vs 87 ± 8 mmHg; P = 0.057), and there was no significant difference in partial pressure of arterial oxygen between the two groups.

CONCLUSIONS

Sustained maternal antenatal sildenafil infusion reduced pulmonary arterial pressure and increased pulmonary blood flow in DH lambs for the first 120 min after birth. These findings of improved pulmonary vascular function are consistent with improved pulmonary vascular structure seen in two previous animal models. The data support the rationale for a clinical trial investigating the effect of antenatal sildenafil in reducing the risk of neonatal pulmonary hypertension in infants with CDH. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Fetal intervention for congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a condition that results from incomplete diaphragm formation during embryogenesis. The diaphragmatic defect allows for herniation of abdominal viscera into the chest, and the resulting pulmonary hypoplasia and pulmonary hypertension can lead to cardiorespiratory failure in the neonatal period. There is a wide spectrum of disease severity in CDH, and while advances in neonatal care and the introduction of extracorporeal membrane oxygenation have improved outcomes in many cases, the most severe defects are still associated with high morbidity and mortality. Improvements in prenatal diagnostic and prognostic capabilities have created an opportunity to select high risk patients for fetal intervention. Three decades of refinements in the fetal surgical therapy for CDH have led to the current technique of Fetoscopic Endoluminal Tracheal Occlusion (FETO). Herein, we review the current considerations for selecting patients for fetal intervention, and the contemporary fetal surgical operation for CDH, FETO, with a focus on early outcomes and ongoing studies.

Prenatal prediction of survival in congenital diaphragmatic hernia: An audit of postnatal outcomes

PURPOSE

Effective antenatal counseling in congenital diaphragmatic hernia (CDH) relies on proper measurement of prognostic indices. This quality initiative audited the accuracy of prenatal imaging with postnatal outcomes at two tertiary pediatric referral centers.

METHODS

Prenatal lung-head ratio (LHR) and total fetal lung volume (TFLV) for CDH patients treated between 2006 and 2017 were retrieved. Study inclusion required at least one LHR or TFLV measurement between 24 and 32 weeks gestational age. Postnatal outcomes [mortality, extracorporeal life support (ECLS) need, patch repair, persistent pulmonary hypertension, oxygen requirement at 28 days] were abstracted from the Canadian Pediatric Surgery Network (CAPSNet) database and local chart review. Univariate and descriptive analyses were conducted.

RESULTS

Eighty-two of 121 eligible CDH patients (68%) were included. Overall mortality, ECLS rates, and patch repair were 33%, 12.5%, and 45%, respectively. Lower LHR values correlated with increased rates of each outcome and persisted despite multiple measurements. Values obtained were higher than those in published schemata. LHR values >45% were most associated with survival, avoidance of ECLS, and primary repair. TFLV values only correlated with mortality and patch repair.

CONCLUSIONS

This audit confirms that LHR and TFLV values predict CDH outcomes. However, absolute values obtained require careful interpretation and internal review.

LEVEL OF EVIDENCE

IV.

Reproducibility of fetal lung-to-head ratio in left diaphragmatic hernia across the North American Fetal Therapy Network (NAFTNet)

OBJECTIVE

To determine the antenatal sonographic lung area measurement method in left congenital diaphragmatic hernia (CDH) with the highest interrater agreement among North American Fetal Therapy Network (NAFTNet) centers within and outside the fetoscopic tracheal occlusion (FETO) consortium and in comparison with a European "expert" reviewer (ER).

METHODS

Nineteen members from nine FETO consortium centers and 29 reviewers from 17 non-FETO centers reviewed ultrasound clips of the chest from 13 fetuses with isolated left CDH and were asked to select a static plane for lung area measurement using anteroposterior (AP), longest, and trace methods. Interrater agreement in lung area measurements was determined using intraclass correlation coefficient (ICC). Bland-Altman analysis was used to evaluate mean difference (bias) between NAFTNet reviewers and ER.

RESULTS

Among FETO centers, agreement was highest using trace (ICC 0.94; 95% CI, 0.83-0.98), followed by longest (ICC 0.89; 95% CI, 0.75-0.97) and lowest for A-P (ICC 0.83; 95% CI, 0.67-0.94). Similar trends were noted in non-FETO centers. When compared with ER, bias was lowest for trace: 14 ± 38 mm² and 19 ± 36 mm² for FETO and non-FETO centers, respectively.

CONCLUSION

The trace method demonstrated the highest interrater agreement and lowest bias for lung area estimation in left CDH across NAFTNet.

Prenatal diagnosis and management of congenital diaphragmatic hernia

Congenital diaphragmatic hernia is characterized by failed closure of the diaphragm, thereby allowing abdominal viscera to herniate into the thoracic cavity and subsequently interfering with normal lung development. At birth, pulmonary hypoplasia leads to respiratory insufficiency and persistent pulmonary hypertension (PHT), that is lethal in up to 32% of patients. In isolated cases, the outcome may be predicted prenatally by medical imaging and advanced genetic testing. In those fetuses with a predicted poor outcome, fetoscopic endoluminal tracheal occlusion may be offered. This procedure is currently being evaluated in a global randomized clinical trial (www.TOTALtrial.eu). We are currently investigating alternative strategies including transplacental sildenafil administration to reduce the occurrence of persistent PHT.