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