Correlation between thromboplastic activity and lecithin/sphingomyelin ratio in amniotic fluid preliminary report

Area of Science:

• Obstetrics and Gynecology
• Neonatal Medicine
• Biochemistry

Background:

• Assessing fetal lung maturity is crucial for managing high-risk pregnancies.
• Lecithin-sphingomyelin (L/S) ratio is a common biochemical marker for fetal lung maturity.
• Thromboplastic activity in amniotic fluid may offer an additional indicator of lung development.

Purpose of the Study:

• To investigate the correlation between amniotic fluid thromboplastic activity and the L/S ratio.
• To determine if amniotic fluid thromboplastic activity can predict fetal lung maturity and the risk of respiratory distress syndrome.

Main Methods:

• Amniotic fluid samples were collected from 59 pregnancies.
• Thromboplastic activity was measured using a modified prothrombin time assay.
• Lecithin-sphingomyelin (L/S) ratio was determined for each sample.
• Correlation analysis was performed between thromboplastic activity and L/S ratio.

Main Results:

• A significant negative correlation (r = -0.73, P < 0.004) was found between amniotic fluid thromboplastic activity and the L/S ratio.
• A prothrombin time of 113 seconds corresponded to an L/S ratio of 2, serving as a threshold for fetal lung maturity.
• In three cases where infants developed respiratory distress syndrome, thromboplastic activity was slower than 113 seconds.

Conclusions:

• Amniotic fluid thromboplastic activity is a reliable indicator of fetal lung maturity, correlating strongly with the L/S ratio.
• Slower thromboplastic activity (longer prothrombin time) is associated with immature fetal lungs and an increased risk of respiratory distress syndrome.
• This assay may serve as a valuable tool in predicting neonatal outcomes.