Validation of a novel birth simulator for impacted fetal head at cesarean section: An observational simulation study

Introduction Impacted fetal head (IFH) is a challenging complication of cesarean section (CS) associated with significant morbidity. Training opportunities for IFH have been reported as inconsistent and inadequate. This study assessed the validity of a novel birth simulator for IFH at cesarean section. Material and methods Obstetricians and midwives collaborated with model-making company, Limbs & Things (UK), to modify the original PROMPT Flex (R) simulator and develop a new "Enhanced CS Module" for IFH at cesarean section. Changes included addition of a retractable uterus and restricted pelvic inlet, and the fetal mannequin was modified to allow accurate limb articulation and flexion at the waist. Obstetricians and midwives from three maternity units in Southwest England were individually recorded, each undertaking three simulated scenarios of IFH at cesarean section. Obstetricians were asked to deliver the fetal head and midwives, to perform a vaginal push-up. Participants completed a questionnaire on realism (face validity) and usefulness for training (content validity) with five-point Likert scale responses. Construct validity was assessed by testing an a priori hypothesis that "experts" (consultant obstetricians with >7 years' experience) would be more likely to achieve delivery than "novices" (registrars with <7 years' experience). Performance variables were compared between groups using Chi-square and Mann-Whitney U-tests. Results In all, 105 simulated scenarios were undertaken by 35 obstetricians and midwives. A range of techniques were employed to deliver the IFH including change of hand, vaginal disimpaction and reverse breech extraction. Overall, 86% (30/35) described the model as fairly (4)/very realistic (5) (median = 4, interquartile range [IQR] = 4-5). The model was considered fairly (4)/very useful (5) for training by 97% (34/35; median = 5; IQR = 5-5). Experts delivered the fetal head in all simulations (36/36) and novices delivered the head in 76.9% (30/39) (p = 0.002). Experts delivered the fetal head 58% quicker than novices (median = 66.8 s, IQR = 53-86 vs median = 104 s, IQR = 67.7-137). Conclusions This novel birth trainer realistically simulates IFH at cesarean section and allows rehearsal of all disimpaction techniques. It was reported to be very useful for training and distinguishes between novice and expert obstetricians. Techniques for IFH are difficult to learn experientially. Simulation is likely to provide an effective and safe form of training.