Evaluation of Fetal Pulmonary Vasculature by Power Doppler Imaging in Congenital Diaphragmatic Hernia

Abstract

Objective. To evaluate the feasibility of prenatal power Doppler imaging of pulmonary arteries in congenital diaphragmatic hernia and to study its potential to predict outcome. Methods. A prospective observational study was conducted. Forty-two cases of congenital diaphragmatic hernia (32 left and 10 right) without associated anomalies were analyzed. Qualitative evaluation of pulmonary vasculature was based on power Doppler imaging performed at 26 to 38 weeks. The pulmonary arteries were studied in the lung contralateral to the hernia. Pulmonary Doppler angiography was considered satisfactory when 3 levels of bifurcation defining 3 distinct segments of the pulmonary arteries were imaged and was otherwise considered poor. We also recorded the gestational age at diagnosis, side of the hernia, abdominal circumference below the third percentile, amniotic fluid volume, lung/thoracic area ratio, left/right ventricle ratio, and, in left-sided hernias, stomach position, and we carried out a multivariate analysis to determine the contribution of each factor to predict neonatal mortality. Results. More than 3 divisions of the fetal pulmonary arteries were imaged in 20 cases; 1 or 2 divisions or none were imaged in 22. Neonatal mortality was significantly greater when fewer than 3 divisions of the pulmonary arteries were imaged (18 [82%] of 22) than when 3 divisions could be identified on power Doppler imaging (5 [25%] of 20; P = .0005). However, the lung/thoracic area ratio was the only factor that remained significantly associated with mortality in the multivariate analysis. Conclusions. An altered pulmonary power Doppler image is associated with neonatal mortality, but estimation of the lung area remains the best predictor of neonatal outcome. Key words: congenital diaphragmatic hernia; lung/head ratio; lung/thorax ratio; power Doppler imaging; prenatal diagnosis; pulmonary hypoplasia; sonography. ongenital diaphragmatic hernia (CDH) diagnosed in utero has a neonatal mortality rate of 50% to 80%, 1-7 death being mainly due to pulmonary hypoplasia. Predicting the neonatal outcome prenatally remains a challenge. Moreover, prenatal staging of CDH is becoming increasingly important as new intrauterine therapeutic interventions emerge, including minimally invasive fetal surgery.8 So far, research on prenatal prediction of pulmonary hypoplasia has focused on using sonography or magnetic resonance imaging to assess the size of the lungs, 7,9-14 the degree of herniation of abdominal organs, 6,15,16 and the consequences of fetal hemodynamic changes on left ventricular size. 17,18 In CDH, however, pulmonary hypoplasia is associated with alterations of the pulmonary vasculature, accounting for potentially lethal postnatal pulmonary hypertension.19

Lung Tissue Blood Perfusion Changes Induced by in utero Tracheal Occlusion in a Rabbit Model of Congenital Diaphragmatic Hernia

“…Two previous studies have used power Doppler methods to assess changes in CDH. Mahieu-Caputo et al [18] qualitatively assessed the pulmonary vasculature using conventional 2D power Doppler imaging and classified cases in severity stages according to the number of divisions of pulmonary arteries that could be visualized. Cases with fewer than 3 divisions had a higher neonatal mortality rate.…”

“…Clinical studies in fetuses with severe pulmonary hypoplasia have reported increased impedance in Doppler vascular blood flow of the intrapulmonary vessels [15][16][17] . In addition, 2 studies have suggested that semiquantitative evaluation of the density of pulmonary vessels estimated by 2D [18] and 3D [19] power Doppler imaging could help to stratify the likelihood of survival in CDH fetuses managed expectantly in utero. Experimental evidence suggests that TO has beneficial effects in the remodeling of the pulmonary arteries, thinning the muscularized pulmonary vessel walls and reducing volume density in pulmonary arteries [20][21][22] .…”

Changes in Lung Tissue Perfusion in the Prediction of Survival in Fetuses with Congenital Diaphragmatic Hernia Treated with Fetal Endoscopic Tracheal Occlusion

“…Earlier studies using semiquantitative methods demonstrated that there is a correlation between the degree of lung perfusion and the severity of CDH [19,20] . More recently, fractional moving blood volume (FMBV), a quantitative method validated against gold standards for fetal evaluation [21] , was used to demonstrate that lung tissue perfusion was reduced in CDH and correlated positively with the o/e LHR [22] .…”

Avaliação do volume pulmonar pela ultra-sonografia em três dimensões em fetos com hérnia diafragmática congênita isolada

“…A presença de polihidrâmnio em casos com HDC é explicada pela compressão mediastinal e do esôfago, levando a menor deglutição de líquido amniótico pelo feto. Porém, outros autores não confirmam essa correlação 29,77 . O desvio grave do mediastino correlacionou significativamente com mau prognóstico em alguns estudos 9,29 , o que não é confirmado em outros 41,73,79 .…”

“…A presença de polihidrâmnio é um exemplo clássico. Resultados iniciais demonstram haver relação desse achado com óbitos neonatais 9,73,74 , porém isso não foi confirmado em outras pesquisas 29,77 nem no presente estudo.…”