(545) Complement 4a (C4a) as a potential biomarker for dystocia in labour

To examine the proteome of the amniotic fluid (AF) in cases of labour dystocia. Previous research has shown high AF lactate to be associated with inefficient uterine action. We aimed to assess the proteome in those with high vs low AF lactate. The aim of this was to allow further insights into labour dystocia.

Study Design:

This was a prospective observational study. 25 patients were recruited with efficient uterine action (EUA), defined as cervical dilation ≥1cm/hour.  25 were recruited with inefficient uterine action (IUA), dilation < 1cm/hour. A sample of AF was collected at the time of caesarean delivery, and the lactate level in the AF was measured. The AF proteome was examined for those with IUA and high (n=4) lactate vs EUA and low (n=4) lactate. 28 differentially expressed proteins (DEPs) were identified using mass spectrometry, these underwent functional pathway analysis. Validation studies were completed using enzyme linked immunosorbent assay (ELISA).

Results:

C4a was identified as being a protein with high fold change (3.12) in low vs high lactate samples. It was also enriched in biological pathway and network analysis of DEPs using KEGG (Kyoto Encyclopaedia of Genes and Genomes). The concentration change in C4a was validated with ELISA, where a higher concentration of C4a was observed in AF with low lactate (p=.00).

Conclusion:

C4a upregulation represents activation of the complement system and inflammation. Progress in labour is dependent on a balance between pro and anti-inflammatory factors. Upregulation of C4a has previously been linked with preterm labour onset. The decreased level of C4a in AF with IUA and high lactate may reflect an imbalance in inflammation. Our findings suggest future research into the role of C4a as a potential biomarker for labour dystocia in AF would be beneficial.