Reliability and validity of clinical and imaging methods in the assessment of the diastasis recti: A systematic review

Introduction: Diastasis recti is often caused by pregnancy in women and may cause complications such as low back pain, lumbopelvic pain, and pelvic floor disorders. Determining the most accurate method to measure diastasis recti is important to estimate the rate of recovery in response to treatment and the need for surgery. Thus, ths study aimed to review the evidence regarding methods of diastasis recti assessment. Materials and Methods: First, databases such as Web of Science, Pro-Quest, Em-base, PubMed, Google Scholar, AMED, and Scopus were searched using related keywords by June 2020. Then, articles were selected based on inclusion and exclusion criteria and the quality of the studies was assessed using the COSMIN checklist. Required information from each article was extracted and the table of characteristics and findings of the articles was recorded. Results: Amongst the 18 included articles, the reliability, and validity of the finger width method, caliper and ultrasonography were studied (one, one, and nine studies, respectively). Additionally, the comparison of the validity of ultrasonography and surgical compass, ultrasonography and the finger width, ultrasonography and caliper, CT scan and ruler, Magnetic Resonance Imaging and ruler, was performed in one, one, two, one, two, and one studies, respectively. Most of the evidence was in the field of ultrasonography and the ICC of this method and caliper was above 0.9. In addition, ICC for agreement between ultrasonography and caliper above umbilicus was more than 0.7 and below umbilicus was less than 0.5. The agreement between raters for the finger width method was moderate (62.5%). There is not enough evidence about other methods. Conclusion: Ultrasonography and caliper are lightly reliable and valid. In addition, these methods are safe and non-invasive. Due to real-time dynamic examination with ultrasonography and the limitation of using the caliper method, ultrasonography seems to be the best method for assessing diastasis recti. However, future studies seem to be necessary due to the heterogeneity of previous studies.