Thermal territories of the abdomen after Caesarean Section birth : infrared thermography and analysis

Objective: To develop and refine qualitative mapping and quantitative analysis techniques to define 'thermal territories' of the post-partum abdomen, the caesarean section site and the infected surgical wound. In addition, to explore women's perspectives on thermal imaging and acceptability as a method for infection screening. Method: Prospective feasibility study undertaken at a large University teaching hospital, Sheffield UK. Infrared thermal imaging of the abdomen was undertaken at the bedside on the first two days after elective caesarean section. Target recruitment: six women in each of three body mass index (BMI) categories (normal, 18.5 to 24.9kg/m²; overweight 25 to <30kg/m²; obese ≥30kg/m²). Additionally, women presenting to the ward with wound infection were eligible for inclusion in the study. Perspectives on the use of thermal imaging and its practicality were also explored via semi-structured interviews and analysed using thematic content analysis. Results: Twenty women were recruited. All had undergone caesarean section. From the booking BMI, eight women were obese (including two women with infected wounds), six women were overweight and six women had a normal BMI. Temperature (oC) profiling and pixel clustering segmentation (Hierarchical Clustering Segmentation, HCS) revealed characteristic features of thermal territories between scar and adjacent regions. Differences in scar thermal intensity profiles exist between healthy scar and infected wounds; features that have potential for wound surveillance. Maximum temperature differences (deltaT) between healthy skin reference and wound site, exceed 2oC in women with established wound infection. At day 2, two women had a scar thermogram with features observed in the ‘’infected’’ wound thermogram. Thermal imaging at early and later times after caesarean birth is feasible and acceptable. Women reported potential benefits of the technique for future wound infection screening. Conclusion: Thermal intensity profiling and HCS for pixel cluster dissimilarity between scar and adjacent healthy skin has potential as a method for the development of techniques targeted to early infection surveillance in women after caesarean section. Key words: Thermal imaging, infrared thermography, abdomen, surgical site infection, Caesarean section, infection surveillance.