Influence of Ultrasound Transducer Tilt in the Cranial and Caudal Directions on Measurements of Inter-Rectus Distance in Parous Women.

Purpose: An increased inter-rectus distance (IRD) can persist after a pregnancy and may be associated with lumbopelvic dysfunction. Ultrasound imaging (USI) is currently the gold standard for measuring IRD; however, no study has explored the need to standardize the transducer angle during these evaluations. The purpose of this study was to determine whether the angle of the ultrasound transducer relative to the underlying abdominal wall has an effect on measurements of IRD in parous women. Method: Ultrasound images of the linea alba (LA) were captured from 15 women, at rest and during a head lift, beginning with images acquired perpendicular to the LA at the midline, then tilted in 5° increments to 15° in both the cranial and the caudal directions. Repeated-measures analyses of variance were used to test for systematic differences in IRD measurements among the transducer angles in both the rest and the head-lift conditions. An α of 0.05 was used for all tests. Results: No significant effect of transducer angle was found in IRD measurements acquired with participants at rest ( F 2.24,31.3 =1.814; p =0.18) or during a head lift ( F 3.15,44.1 =1.315; p =0.28). Conclusion: When using USI, cranial or caudal tilt errors in transducer angle do not appear to pose a problem when measuring IRD.