Data Collection
Consecutive patient case notes were reviewed prospectively as part of an ongoing service evaluation over a defined time period and therefore a power calculation was not performed prior to analysis. Data was organised into five groups according to the initial attempt at delivery once the patient had been moved to obstetric theatre: (1) Keilland’s Forceps Delivery (KFD), (2) Direct Forceps Delivery (DFD), (3) Manual Rotation plus direct Forceps Delivery (MR + FD), (4) Ventouse Delivery (VD) and (5) Primary emergency full-dilatation Caesarean Section (pEmCS). Regardless of the final mode of delivery, all subsequent outcome data was analysed within these groups as per an ‘intention to deliver’ analysis.
Demographic data variables collected can be observed in Table 1 and in-labour and delivery variables in Supplementary Table 1. In cases where instrumental delivery was attempted (Groups 1-4) data was collected as to whether a successful vaginal delivery was achieved.
The immediate perinatal adverse outcome data collected were agreed via author consensus. These can be viewed in Table 2 and were grouped into maternal and neonatal outcomes. Maternal injury at instrumental was pre-defined as a cervical or significant vaginal laceration other than 3rd or 4th degree tear. Maternal injury at Caesarean section was pre-defined as a significant uterine or pelvic extension of excision, or an abdominal visceral injury. An overall composite risk score was produced from the maternal plus neonatal outcome data.