Review question / Objective: The scoping review aims to identify publications describing the measurement of inter-recti distance (IRD)/diastasis recti abdominis (DRA) using ultrasonographic imaging (USI). The identification is based on the population/concept/context (PCC) framework that concerns human adults that underwent IRD/linea alba width/DRA measurement with USI for physiotherapy/physical exercise purposes. Based on systematically mapped peer-reviewed studies it is aimed to perform data extraction and synthesis of specific aspects of the IRD measurement procedure and discuss their similarities and differences. Related to that the attempt will be made to formulate recommendations on the IRD measurement procedure, which might be considered in future physiotherapy studies and practice. The recommendations will be made based on the synthesis of the results in light of existing literature and as the result of discussions and consensus between the authors (coming from three research centers).

Background Inter-recti distance (IRD) measurement using musculoskeletal USI has been used in physiotherapy research, in particular, to investigate pregnancy-related diastasis recti abdominis (DRA) and to seek its effective treatment methods. Severe and untreated diastasis may result in the formation of umbilical or epigastric hernias. Objective This study aimed to systematically map physiotherapy-related research articles that included descriptions of IRD measurement procedures using USI to present their similarities and differences, and formulate recommendations on the procedure. Design A scoping review was conducted according to PRISMA-ScR guidelines, including 49 of 511 publications from three major databases. Publications were selected and screened by two independent reviewers whose decisions were consulted with a third reviewer. The main synthesized data items were: the examinees’ body position, breathing phase, measurement sites, and DRA screening methods. The final conclusions and recommendations were the result of a consensus between seven reviewers from four research centers. Results Studies used 1–5 measurement sites that were differently determined. IRD was measured at the umbilicus (n = 3), at its superior (n = 16) and/or inferior border (n = 9), and at different levels: between 2 and 12 cm above the umbilicus, or a third of the distance and halfway between the umbilicus and xiphoid (n = 37); between 2 and 4.5 cm below the umbilicus or halfway between the umbilicus and pubis (n = 27). Different approaches were used to screen subjects for DRA. Conclusions The discrepancies between the measurement procedures prevent between-study comparisons. The DRA screening method should be standardized. IRD measurement protocol standardization has been proposed. Critical relevance statement This scoping review indicates that the inter-recti distance measurement procedures using ultrasound imaging differ between studies, preventing between-study comparisons. Based on the results synthesis, the measurement protocol standardization has been proposed. Key points The inter-recti distance measurement procedures using USI differ between studies. Proposed standardization concerns body position, breathing phase, measurements number per location. Determination of measurement locations considering individual linea alba length is suggested. Recommended locations: umbilical top, ½ of umbilical top-xiphoid, ¼ of umbilical top-xiphoid/pubis distances. Diastasis recti abdominis diagnostic criteria are needed for proposed measurement locations. Graphical Abstract

Background: With the increased interest in inter-recti distance measurement using ultrasound imaging, there is a question of measurement reliability, and the importance of the examiner’s experience. Methods: The study aimed to investigate the reliability of the inter-recti distance measurement performed offline by an experienced radiologist on linea alba images captured by two novice examiners. Additionally, it was aimed to determinethe number of image repetitions that provide an acceptable measurement reliability level. Ultrasound images were acquired by two novice examiners on repeated occasions (sessions A and B) in twenty-eight nulliparous women of reproductive age. Five images were captured at supraumbilical, umbilical, and infraumbilical points during each session. Results: The excellent intra-examiner reliability of inter-recti distance measurements was shown at the supraumbilical and umbilical levels (ICC=0.894-0.983). Infraumbilical measurements had good to excellent reliability (ICC=0.894-0.972). Session A inter-examiner reliability was excellent for the mean measurements of two, three, four, and five images taken at each location (ICC=0.913-0.954). Session B inter-examiner reliability was excellent for the mean measurements of two, three, four, and five images taken at the supraumbilical and umbilical (ICC=0.94-0.98) and good (ICC≥0.81) at the infraumbilical locations. Some images were unusable (1.6% of images of Examiner 1 and 2.2% of Examiner 2). Conclusions:Novice examiners were able to capture good-quality ultrasound images of the linea alba that allowed for excellent intra- and inter-examiner reliability of supraumbilical and umbilical measurements, and good to excellent reliability of inframbilical measurements in nulliparas.