Physiotherapists' reliability of inter-recti distance measurement with real-time ultrasound across a mixed women population sample.

Background: Ultrasound imaging has become popular among physiotherapists for monitoring diastasis rectus abdominis postpartum, but its reliability requires further exploration.

Objectives: To investigate physiotherapists' intra-tester, inter-tester, and test-retest reliability of inter-recti distance measurement utilizing real-time ultrasound across a mixed women sample.

Design: Reliability study.

Methods: Volunteers comprising nulliparous and parous women of different ages and body mass index participated. Five physiotherapists performed ultrasound measurements, following sonographic training. Four conditions were tested in supine; rest, curl-up, transversus abdominus activation, and transversus abdominus with curl-up. Three locations were randomly measured: umbilicus, 3 cm above the umbilicus, and halfway between the umbilicus and xiphoid process. For intra-tester reliability, each therapist undertook three repeated measurements. For inter-tester reliability, mean inter-recti distance measurements were explored across any two tester combinations within and across sessions. Test-retest reliability explored repeated measurements 5-8 days later. Data were analyzed with intraclass correlation coefficients.

Results: 54 women (33.2 ± 15.2 years old, body mass index: 24.2 ± 3.7), 19 (35.2%) being parous participated. Intra-tester reliability across each physiotherapist was very good (intraclass correlation coefficients = 0.677-0.989). Intra-session reliability across any two testers yielded very good results (intraclass correlation coefficients = 0.76-0.92), whereas across-session yielded good reliability (intraclass correlation coefficients >0.76) except for one condition (3 cm above umbilicus in combined transversus abdominus and curl-up). Test-retest reliability was also very good (intraclass correlation coefficients = 0.78-0.96). Significant differences in inter-recti distance were found, with parous women showing consistently larger values (p < 0.05).

Conclusion: Physiotherapists, following sonographic training, can reliably measure inter-recti distances in both nulliparous and parous women across active and resting tasks. Thus, ultrasound measurement of inter-recti distance is recommended in physiotherapy practice for monitoring diastasis rectus abdominis and assessing rehabilitation progress. However, sub-umbilical inter-recti distance measurements and the impact of co-contraction on reliability require further research.