Background: Several methods were presented to estimate fetal lung maturity (FLM), including the lecithin/sphingomyelin ratio measurement, the phosphatidylglycerol existence or deficiency, and the lamellar body count in amniotic fluid (AF). However, all of these methods necessitate amniocentesis, which is an invasive process. Non-invasive ultrasound (US) methods have been studied to predict FLM.
Objectives: This study objective was to assess the various grey scale and color doppler US parameters accuracy and to identify the most sensitive and specific parameter as a non-invasive approach for predicting FLM.
Patients and methods: This prospective study was conducted on 100 pregnant women, aged 18 to 37 years old, who were experiencing a normal singleton pregnancy with a viable fetus and routine fetal surveillance between 34 and 40 weeks of gestation. All patients were investigated to: History taking, sonographic assessment, conventional 2D US, Epiphyseal ossification centers (EOC), placental grading, AF index and free-floating particles, thalamus echogenicity, fetal lung echogenicity, and doppler examination.
Results: Ultrasound parameters we found that EOC of the tibia has the highest accuracy 94% followed by EOC of the femur with accuracy 92 % then free-floating particles presence in AF with accuracy 83% and thalamic echogenicity with accuracy 80% and the least accuracy was for humerous OC 54% and lung echogenicity 45%. In concerning to doppler indices we noticed that Main pulmonary artery acceleration time / ejection time (MPA AT/ET) ratio cutoff value of 0. 295 showed the highest accuracy 94. 9% followed by Middle cerebral artery resistive index (MCA RI), Umbilical artery pulsatility index (UA PI), Umbilical artery resistive index (UA RI) and Main pulmonary artery resistive index (MPA RI) respectively.
Conclusions: Utilizing US and doppler to assess FLM is helpful. However, no single parameter alone could demonstrate definite sign of fetal lung maturity.