Study design: Clinimetrics.
Objectives: To investigate the intrarater between-session reliability of inter-rectus distance (IRD) measurement using ultrasound imaging in postpartum women with diastasis recti.
Background: Diastasis recti, a separation of the rectus abdominis muscles at the linea alba, occurs as a result of pregnancy and is characterized by increased IRD. The measurement of IRD in this population is of interest to determine changes in diastasis recti severity over time, or in response to treatment. Ultrasound imaging has been proposed as a useful tool to measure IRD in women with diastasis recti; however, the consistency of IRD measurement in this population using ultrasound imaging has, to our knowledge, never been investigated.
Methods: Ultrasound imaging was used to measure IRD in 20 women with diastasis recti on 2 different occasions. On each testing occasion, images were acquired at 4 locations along the linea alba while participants remained relaxed and while they performed a head lift to activate the rectus abdominis muscles. Reliability statistics included intraclass correlation coefficients, Bland-Altman analyses, minimum clinically important difference, and standard error of the measurement.
Results: Between-session reliability of IRD measurement was high, particularly when measuring IRD at or above the umbilicus, as indicated by intraclass correlation coefficients greater than 0.90 and low standard error of the measurement and minimum clinically important difference values (below 0.17 cm and 0.46 cm, respectively). Reliability coefficients were poorer when measuring IRD below the umbilicus.
Conclusion: When performed by an experienced investigator, ultrasound imaging is a reliable tool by which to measure IRD in postpartum women who have diastasis recti.
Keywords: abdominals; inter-rectus distance; linea alba; rectus abdominis; width.