VP45.11: Association of cephalopelvic disproportion with ischial spine and ischial tubercle distances in Caesarean section deliveries

This study aimed to investigate the correlation between height and bony pelvimetry and determine the difference in bony pelvimetry between the vaginal delivery and Caesarean section group with the cephalopelvic disproportion. This study was a retrospective study of women who underwent pelvic MRI between January 2014 and June 2020 at Bundang CHA Hospital. 392 patients of 431 patients of reproductive age who were performed pelvic MRI were recruited. We divided into three groups ( group 1: vaginal delivery, group 2: Caesarean section with the cephalopelvic disproportion, group 3: Caesarean section for other reasons) and analysed the difference of inlet distance, mid pelvis, outlet distance, and pubic angle among groups. The R program was used for statistical analysis, and a P value of ≤ 0.05, was considered significant. T-test, ANOVA, Kruskal-Wallis H test, Tukey's post-hoc test. There was no significant difference in inlet distance, mid pelvis distance, outlet distance, and pubic angle when we divided only vaginal delivery and Caesarean section group. However, when we divided into three groups (group 1: vaginal delivery, group 2: Caesarean section with the cephalopelvic disproportion, group 3: Caesarean section for other reasons, Midpelvis distance ( Ischial spine distance ) and outlet distance ( ischial tubercle distance) are the shortest in group 2. Each ischial spine distance was 108.8 ± 8.0c cm in group1, 105.2 ± 6.6 cm in group 2, 110.8 ± 9.4 cm in group 3 ( P-value =0.08 ). Each ischial tubercle distance was 119.9 ± 10.2 cm in group 1, 117.1 ± 9.5 cm in group 2, 122.7 ± 12.0 cm in group 3 ( P-value =0.032 ). Cephalopelvic disproportion is associated with maternal and fetal morbidity and mortality. The bony pelvis plays a more important role than maternal height in cephalopelvic disproportion. Shorter mid pelvis (ischial spine distance) and outlet pelvis (ischial tubercle distance) are related to cephalopelvic disproportion. We need to evaluate the mid pelvis and outlet pelvis before or during labour.