P04.05: Measurement of retropubic tissue thickness using intrapartum transperineal ultrasound to assess cephalopelvic disproportion (CPD)

Abstract

To describe a new method to assess CPD by measuring the retropubic tissue thickness (RTT) and secondly to determine whether RTT is associated with the eventual delivery by Caesarean section (CS). Three-dimensional transperineal ultrasound scans were performed on 129 labouring nulliparous women to obtain 3D volume data sets for assessment of the RTT. The RTT was measured off-line by three operators as the shortest distance between the capsule of the pubic symphysis and the outer border of the fetal skull with an angle of progression of <120 degrees. The intra-operator repeatability and the inter-operator reproducibility were determined. RTT in women who were delivered by CS for failure to progress were compared against those of women who achieved a vaginal delivery (VD). The RTT intra-operator repeatability was 1.2mm. The overall RTT inter-operator interclass correlation was 0.97 (0.95 to 0.98). The RTT in women who had spontaneous, instrumental or CS were 1.16±0.32cm, 1.12±0.25cm and 0.94±0.25cm respectively. Women who were delivered by CS had significantly smaller RTT compared to women who had a spontaneous (p=0.004) or instrumental delivery(p=0.02). There was no significant difference in RTT between those who had instrumental or spontaneous delivery (p>0.05). Supporting information can be found in the online version of this abstract Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.