Postpartum characteristics of rectus abdominis on ultrasound imaging.

This cross-sectional and partial longitudinal study aimed to characterize changes in rectus abdominis (RA) and provide reference ranges for the first year postpartum. Ultrasound scanning was used at four stages postnatally to measure cross-sectional area (CSA), thickness, width (indirectly using a shape value) and inter-recti distance (IRD). One hundred and fifteen postnatal women (though some postnatal subjects appeared in more than one postnatal group thus giving a total of 183 data points) and 69 age-matched nulliparous female controls were recruited. Postnatal subjects were studied at Day 1 (PN1; n=63) and at 2 (PN2; n=55), 6 (PN3; n=39) and 12 (PN4; n=26) months postpartum. Longitudinal data were analysed for CSA, thickness, shape (indirect width measurement) (df=67) and IRD (df=62). The mean CSA of the PN1 group was significantly larger (P<0.001) than in controls and decreased (P<0.0021) by 12 months. In all postnatal groups, RA was significantly thinner (P<0.0001, PN1-PN3; P<0.0478, PN4), wider (P<0.0001, PN1-PN3; P=0.0326, PN4) and the IRD was significantly larger (P<0.0001, PN1-PN4) than in controls. Over 2 months postpartum, RA became thicker (P=0.0003) and the width and IRD decreased (P<0.0001 and P=0.0002, respectively) but did not return to control values by 12 months. These results have implications for strength of RA postpartum and anterior abdominal wall stiffness, which together with other muscle characteristics could inform development of effective postnatal exercise programmes.

Rehabilitative ultrasound imaging: understanding the technology and its applications.

The use of ultrasound imaging by physical therapists is growing in popularity. This commentary has 2 aims. The first is to introduce the concept of rehabilitative ultrasound imaging (RUSI), provide a definition of the scope of this emerging tool in regard to the physical therapy profession, and describe how this relates to the larger field of medical ultrasound imaging. The second aim is to provide an overview of basic ultrasound imaging and instrumentation principles, including an understanding of the various modes and applications of the technology with respect to neuromusculoskeletal rehabilitation and in relation to other common imaging modalities.