Objective To explore optimum use of the Odon Device by establishing the optimal device design, describing the ‘usual’ steps for use and setting clinical parameters for device use. Design Qualitative case study methodology was embedded in the ASSIST Study – a feasibility study of the Odon Device. Setting Central Delivery Suite, North Bristol NHS Trust, UK. Population Women who required a clinically indicated assisted vaginal birth. Methods Each case was determined by the single use of the Odon Device and could contain data from one or more of the following: formal observation of the Odon assisted birth, an interview with obstetricians, midwives or women involved in an Odon assisted birth. Data collection and analysis ran iteratively and in parallel enabling rapid dissemination of findings. Main outcome measures Determining the optimal steps for device use, recommendations for optimal device design and defining clinical parameters for device use. Results Optimal steps included applying the device during rather than between contractions, having a flexible approach to the application angle and deflating the air cuff sooner than originally proposed. Three design modifications were proposed. The device can be used under local or regional anaesthetic and is successful with all vertex presentations. It is not successful at assisting birth when the vertex is at station spines. Conclusions Case study methodology facilitated rapid insight into optimum device design, device use and key clinical parameter for successful use. This methodology should be considered whenever innovative devices are introduced to clinical trials and settings.

Background Assisted vaginal birth (AVB) is a complex intervention involving medical devices, comprising multiple components. This complexity creates difficulties when designing and conducting randomised controlled trials (RCTs), in terms of describing, standardising and monitoring the intervention, and accounting for differing clinician expertise. Objectives This review examines the reporting standards of complex interventions involving a medical device, in the context of AVB RCTs. Search Strategy Searches were undertaken from the start of indexing to November 2018, and limited to RCTs, feasibility and pilot studies including at least one device for AVB. Selection Criteria RCTs were selected if they included participants having an AVB with any device, with or without a comparator group. Data Collection and Analysis Reporting details were assessed according to the Consolidating Standards of Reporting Trials extension for non-pharmacological treatments (CONSORT-NPT), focusing on intervention descriptions, standardisation, adherence and clinician expertise. Main Results Of 2,510 abstracts and 74 full-text articles, 36 papers were included, investigating 73 interventions. Twenty-eight different named devices were identified. Intervention descriptions were provided in 20(56%) papers with varying levels of detail and none covered the entire procedure. Standardisation of interventions was mentioned in 23 papers (64%). Only seven(19%) papers reported any form of adherence to the intended procedure. Some data regarding expertise were reported in 23(64%) papers. Conclusions Despite some compliance with reporting standards, there is a lack of detail regarding intervention description, standardisation, adherence and expertise in RCTs of AVB. This creates difficulties in understanding how intervention delivery was intended and what actua