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Background and Aims Epidural catheter placement is crucial for effective postoperative pain management in abdominal surgery. However, its success relies on accurate localization within the epidural space, which can be challenging due to anatomical variations and operator-dependent factors. In this study, ultrasound is compared with sensory assessment of the block (pinprick and cold pressure). Ultrasound, particularly using color Doppler and M-mode, has shown promise for catheter localization, but its interobserver and intraobserver variability remain unclear.

Methods Determine the interobserver and intraobserver variability of ultrasound in detecting epidural catheters and assessing their efficacy in abdominal surgery. Methods: A diagnostic test study was conducted to analyze interobserver and intraobserver variability in measuring skin-to-posterior complex and skin-to-anterior complex distances and determining catheter placement in the epidural space using qualitative method with color Doppler and M-mode ultrasound. Three anesthesiologists were included. Statistical analysis, including intraclass correlation for continuous variables and kappa coefficient for categorical variables, was performed. Bland-Altman plots were constructed to visualize agreement between observers.

Results The study included 125 patients who provided consent to participate, 75 were women. Preliminary analysis revealed a good intraclass correlation for distances. Kappa index for M-mode was better (see table 1 and 2), indicating consistency in measurements and catheter placement assessment.

Conclusions Initial findings suggest promising interobserver and intra-observer agreement in ultrasound-guided epidural catheter localization and efficacy assessment. The low inter- and intra-observer variability observed in this study supports the clinical applicability of ultrasound. Further analysis with a larger sample size is warranted to validate these results.