Ultrasonographic occiput position in early labour in the prediction of caesarean section

Objective To investigate the value of ultrasonographically determined occiput position in the early stages of the active phase of labour, in addition to traditional maternal, fetal and labour-related characteristics, in the prediction of the likelihood of caesarean section. Design Prospective observational study. Setting District general hospital in the UK. Population Six hundred and one singleton pregnancies with cephalic presentation in active labour at term with cervical dilatation of 3-5 cm. Methods Transabdominal sonography to determine fetal occiput position was carried out by an appropriately trained sonographer immediately before or after the routine clinical examination by the attending midwife or obstetrician. Main outcome measure Caesarean section. Results Delivery was vaginal in 514 (86%) cases and by caesarean section in 87 (14%). The fetal occiput position was posterior in 209 (35%) cases and in this group the incidence of caesarean section was 19% (40 cases), compared with 11% (47 of 392) in the non-occiput posterior group. Multiple regression analysis revealed that significant independent contribution in the prediction of caesarean section was provided by maternal age (OR 1.1, 95% CI 1.0-1.2), Afro-Caribbean origin (OR 2.4, 95% CI 1.2-4.6), height (OR 0.93, 95% CI 0.89-0.97), parity (OR 0.2, 95% CI 0.1-0.4), type of labour (OR 2.2, 95% CI 1.3-3.8), gestation (OR 1.4, 95% CI 1.1-1.7), fetal head descent (OR 0.6, 95% CI 0.4-0.9), occiput posterior position (OR 2.2, 95% CI 1.3-3.7) and male gender (OR 2.0, 95% CI 1.2-3.5). Conclusions The risk of caesarean section can be estimated during the early stage of active labour by the sonographically determined occiput position, in addition to traditional maternal, fetal and labour-related characteristics.