Relationship between length and width of the purple line and foetal head descent in active phase of labour

Abstract

Purple line is one of the non-invasive methods to assess the progress of labour. This longitudinal observational study was performed on 350 women during the active phase of labour. We assessed the relationship between length and width of the purple line and foetal head descent. Women were examined in the lateral position and researcher recorded the presence or absence of the line before each vaginal examination. Where present length and width of the line was measured using a disposable tape measure. The purple line appeared in 75.3% of 350 women during the active phase of labour. There was a positive correlation between length of the purple line and station of the foetal head (r = +0.29, p = .001). There was also a medium positive correlation between width of the purple line and the station of the foetal head (r = +0.71, p < -.001). There is a positive correlation between purple line and station of the foetal head. Where the purple line is present, measurement of it may reduce the number of vaginal examinations, especially when the single aim is to measure station of the foetal head. Further research is needed to confirm the current finding in other races. IMPACT STATEMENT Current knowledge on the subject: In the literature, purple line is one of the non-invasive methods to assess the progress of cervical dilatation and foetal head descent in labour. Failure of the foetal head is the second most common indication for performing surgical deliveries. Progression of labour has been evaluated by vaginal examination for the assessment of cervical dilatation and foetal head station. Vaginal examinations can be unpleasant, intrusive, embarrassing and so painful for women. Researchers suggested to explore whether the line is also present in women across other ethnic and racial groups and they also suggested further researches to examine the width of purple line. The contribution made by the results of this study: The results of this study add to the growing body of research on progression of labour that the purple line appeared in most of Iranian women during the active phase of labour. There was a positive correlation between length and width of the purple line and station of the foetal head. The implications are of these findings for clinical practice and further research: The results of this study can be used reduce the number of vaginal examinations, especially when the single aim is to measure station of the foetal head. Further research is needed to confirm the current finding in other races.

Keywords: Foetal head station; active phase of labour; length of purple line; vaginal examinations; width of purple line.