Use of ultrasound in assessment of necrotic tissue in pressure ulcers with adjacent undermining

Objective: To reveal the specific ultrasonic imaging findings of non-visible necrotic tissue in pressure ulcers (PUs) with undermining and describe the images objectively. The predictive validity of the specific images of the undermined necrotic tissue was also determined. Method: Using digital ultrasonography (12MHz linear transducer, MyLab25; Hitachi Medical Corporation), we imaged PUs with undermining every 2 weeks. PUs were also monitored by DESIGN-R, a PU assessment tool, at the same time. Results: Ten patients had 11 PUs with undermining and all ulcers were located in the sacral region. The necrotic tissue showed high echogenicity with no layers, unclear borders and an uneven gray level (cloud-like image). Granulation tissue appeared as a low echoic image which had no layers, was of coarse resolution and an even gray level. There were significant differences between the pixel uniformity of the necrotic tissue (84.0) and granulation tissue (53.9) compared with uninjured tissue (65.5; p=0.000 and 0.005, respectively). The sensitivity, specificity, and positive and negative predictive values of cloud-like image were 87.5%, 91.7%, 77.8% and 95.6%, respectively. Conclusion: The results suggest that cloud-like image is the most useful diagnostic indicator for non-visible necrotic tissue in PUs with undermining and is the best prognostic indicator for PU healing. Declaration of interest: The authors have no conflicts of interest to declare. There were no external sources of funding for this study.