Reliability of inter-recti distance measurement on ultrasound images captured by novice examiners.

Background: With the increased interest in inter-recti distance measurement using ultrasound imaging in physiotherapy, there is a question of measurement reliability, and the importance of the examiner's experience.

Purpose: The study aimed to investigate the reliability of inter-recti distance measurement in a DICOM viewer software by an experienced radiologist. For the measurement, the radiologist used linea alba images captured by two physiotherapists who were novice examiners.

Methods: Ultrasound images were acquired by two novice examiners on repeated occasions 7 days apart (sessions A and B) in 28 nulliparous women at supraumbilical, umbilical, and infraumbilical locations along linea alba.

Results: Excellent intra-examiner reliability of inter-recti distance measurements was shown at the supraumbilical and umbilical levels (ICC_2,k = 0.941-0.983) with minimal detectable change (MDC₉₅) ranging from 1.31 mm to 2.29 mm. Infraumbilical measurements had good to excellent reliability (ICC_2,k = 0.894-0.972) with MDC₉₅ ranging from 0.33 mm to 0.72 mm. Session A inter-examiner reliability was excellent for the mean measurements of two, three, four, and five images taken at each location (ICC_2,k = 0.913-0.954) with MDC₉₅ ranging from 0.47 mm to 2.96 mm. 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_2,k = 0.94-0.98), MDC₉₅ ranging from 1.38 mm to 2.58 mm and good (ICC_2,k ≥ 0.81) with MDC₉₅ ranging from 0.72 mm to 0.80 mm at the infraumbilical locations.

Conclusion: Novice examiners were able to capture good-quality ultrasound images of the linea alba that allowed for good to excellent intra- and inter-examiner reliability.