Purpose: To evaluate and compare the consistency of agreement of two methods for measuring abdominal rectus diastasis (ARD), preoperative computed tomography (CT) scanning and preoperative clinical assessment were compared with direct measurement intraoperatively.
Methods: Fifty-five consecutive patients were retrieved from an ongoing prospective randomised trial comparing two operative techniques for the repair of ARD. All patients underwent a preoperative clinical assessment and CT scan, and the results were compared with intraoperative measurement of the ARD width. Agreement between methods was described with Bland-Altman plots (BA plots) and calculated using Lin's Concordance Correlation Coefficient (CCC).
Results: The median width of the diastasis was 4.0 cm in the upper midline and 3.0 cm in the lower midline for the intraoperative measurement. BA plots showed that measurements on CT and intraoperatively are not in agreement in the lower midline, whereas the agreement was stronger between the clinical and the intraoperative method. The CCC was higher for clinical vs. intraoperative measurement (0.479) than for CT vs. intraoperative measurement (-0.002) in the lower midline, although the agreement was over all low. CT scanning underestimated the width of the ARD when compared to 87 % of preoperative clinical assessments, and 83 % of intraoperative measurements. Preoperative clinical assessment overestimated ARD in 35 % when compared with intraoperative measurements.
Conclusion: Clinical assessment prior to surgery provides more accurate information than CT scanning in the assessment of ARD width. CT scanning underestimates ARD width when compared with intraoperative measurement.