Foetal Pulmonary Artery Derived Doppler Parameters for Foetal Lung Maturity Assessment: An Observational Study

Abstract

Introduction: Neonatal Respiratory Distress Syndrome (RDS) is a major cause of foetal mortality and morbidity, especially in preterm labour because of concerns about foetal lung maturity. One of the method to assess foetal lung maturity is the Doppler assessment of the foetal Pulmonary Artery. Aim: To assess the accuracy of Doppler findings of the foetal Main Pulmonary Artery (MPA) in foetal lung maturity assessment and prediction of the development of neonatal RDS in preterm deliveries. Materials and Methods: A prospective observational study was conducted in the Department of Radiology, along with the Departments of Obstetrics and the Department of Paediatrics of Rama Medical College, Hospital, and Research Institute in Kanpur, India from May 2022 to December 2022. A total of 76 pregnant women with singleton pregnancies and gestational age <37 weeks were included. Clinical history and relevant clinical examination data were collected from the patients. Ultrasound examination began with a general survey of the gestational sac, foetal biometry, detailed anatomical evaluation for any evident anomalies, and then cardiac evaluation. The Doppler waveform of the MPA was confirmed by its characteristic ‘spike and dome pattern’. It was distinguished from the ductus arteriosus waveform, as it shows a triangular waveform with increased diastolic flow. Acceleration Time (AT) was measured from the start of the systolic wave to the first systolic peak. Ejection Time (ET) measurement included the entire systolic wave. The diagnosis of RDS was made by the paediatrician, who was blinded to the Doppler findings. Receiver Operating Characteristic (ROC) curves were drawn using Statistical Package for the Social Sciences (SPSS) software to assess the diagnostic ability of the Doppler findings and to find the cut-off values with maximum sensitivity and specificity. Results: Out of the 76 pregnant women included in this study, 14 were excluded due to inadequate Doppler measurements and not being able to give birth within one week of Doppler evaluation. The study assessed a total of 62 pregnant females who underwent preterm delivery following the Doppler study. In total, 28 neonates developed RDS. Doppler parameters of both groups were compared (the first group included pregnant women whose neonates developed RDS after birth, and the second group included pregnant women whose neonates didn’t develop RDS after birth) with the help of the ROC curve. The AT/ET ratio achieved the highest sensitivity and specificity, both at 82%. Conclusion: The AT/ET ratio has produced the best results among all foetal pulmonary artery-derived Doppler parameters and is a promising non invasive method for assessing foetal lung maturity.

Keywords

• acceleration time
• ejection time
• neonatology
• ultrasonography