Thermography as a diagnosis support tool in caesarean infections

Thermography as a diagnosis support tool in caesarean infections

16/02/2022 By: Nieves Fernández López & Alejandro del Estal Home

Could caesarean infections be prevented using thermography as a diagnosis support tool? After a ceasarean delivery, in order to avoid the risks of an eventual infection, thermography can be used as a tool to assess the severity and location.

Surgical site infection (SSI) is a serious complication to abdominal surgery causing increased morbidity (Coello et al. 2005) and can be suffered by 19 to 32% of women (Connolly et al., 2016). Obesity seems to be one of the factors associated with wound dehiscence and has been a subject of concern due to the global rise in adult obesity, in addition to being associated, as mentioned earlier, with morbidity (Anaya, D. A., & Dellinger, E. P., 2006).

After abdominal delivery and caesarean section, infections can occur in all three of the surgical site infection (SSI) categories, as can be seen in figure 1 (Horan, T. C., et al. 1992):

  • Superficial incisional SSI, which only involves the skin and subcutaneous tissue
  • Deep incisional SSI, which involves deep soft tissue of the incision
  • Organ SSI, which involves any part of the anatomy (organs or spaces)
Figure 1. Schematic of the anatomy of SSIs and their appropriate classifications (Horan, T. C., et al. 1992).

The Centers for Disease Control and Prevention (CDC) criteria are the most widely implemented standard definition for SSI. In table 1, you can see the CDC criteria and the ASEPSIS  (Additional treatment, presence of Serous discharge, Erythema, Purulent exudate Separation of the deep tissue, Isolation of bacteria and duration of Stay) score for diagnosing surgical site infection (Henriksen et al. 2010):

Table 1. Components used in the Centers for Disease Control and Prevention (CDC) criteria and the ASEPSIS score for diagnosing surgical site infection

The aims of the research in this field of caesarean scar or wounds and thermography in Childs et al. (2016) and in Siah, C. J. R., & Childs, C. (2015) were :

  • Define the ‘thermal territories’ of the post-partum abdomen, surgical site, and infected surgical wound.
  • Develop robust qualitative mapping and quantitative analysis systems.
  • Seek the perspectives of women on the potential of thermal imaging as a wound surveillance technique. 
  • Effects of body composition on abdominal skin surface temperature readings
  • Characteristic of infected versus non-infected wounds.

Frequent factors in caesarean infections and wounds

What seems to happen while comparing healing and infected wounds, is that healing wounds showed a trend in the thermal map where the temperature increased on the first postoperative day and warmed over the subsequent five days, while cold spots emerged on the thermogram of the surgical wounds which subsequently became infected in Figure 2 (Siah, C. J. R., & Childs, C. 2015).

Figure 2. IR image of the abdominal skin surface area of a non-infected wound (left) and infected (right) wound after surgery. (Siah, C. J. R., & Childs, C., 2015).

Siah, C. J. R., & Childs, C. (2015) mapped the temperature of the healing surgical wound in cases of post-stoma-closure, finding out that, healing wounds showed changes in the thermal “map”; an increase in temperature on the first post-operative day, and “warming” over the subsequent five days.

However, as was observed in Childs et al. study (2019), due to a possible reduction in cutaneous blood flow, cold spots emerged on the thermogram of surgical wounds which subsequently were shown to be infected like in Childs et al. (2016) study (Figure 3).

Figure 3. Thermal image data of a caesarean wound with a rectangular region of interest (ROI) where 5 cold spots can be seen (Childs et al., 2016).

On the other hand, most of the wound infections are superficial (96%), affecting the skin and subcutaneous tissue only (Zejnullahu et al. 2019). Thus, adiposity appears to play a key role in susceptibility to wound infection. Soper et al (1995) showed that it is abdominal subcutaneous tissue thickness (rather than weight or BMI per se) that represents a significant infection risk factor in the region of the abdominal wound incision after caesarean. Therefore, this suggests that there thicker the subcutaneous tissue, the greater the risk that infection may arise. However, Vermillion et al. (2000) showed that intraoperative measurement of subcutaneous tissue thickness was not a useful diagnostic test for later postoperative infection. Nevertheless, the role that subcutaneous fat may play in the etiology of postoperative wound complications, such as infections, after caesarean section merits further investigation.

Benefits of the use of thermography in caesarean infections

Even though there are limitations such as the sample size, in Childs et al. (2016) study, they found out that thermography can help observe differences in IR radiation intensity, for example, cold spots which could potentially represent a means to stratify women to high and low SSI risk categories. Also, after 2 weeks they saw skin breakdown, granulation tissue, and purulent exudate on IR imaging as either discrete cold spots or as large contiguous regions, arising from the original scar.

The women that took part in the study, described this technique as a non-invasive, straightforward approach, safety, pain-free and harmless therefore a good option for future developments in infection screening. Also, the potential benefits of using thermal imaging routinely are, reducing the number or severity of infections, knowing their infection risk, starting treatment earlier, decreasing morbidity and length of hospital stay, and preventing the negative impact on maternal-infant bonding of having an ill mother.

CONCLUSION

To sum up, we have to take into account the BMI, the abdominal subcutaneous tissue thickness and the appearance of cold spots in the wound are essential factors to prevent the infection of a caesarean wound. Besides, the appearance of cold spots can help prevent a week ahead of caesarean wound infections. Thermography seems to be another useful tool to assess the severity and location of the infection, because it is non-invasive, and according to the women who have participated in some of the studies it is harmless and safe.


REFERENCES

Anaya, D. A., & Dellinger, E. P. (2006). The obese surgical patient: a susceptible host for infection. Surgical infections, 7(5), 473-480.

Childs, C., Siraj, M. R., Fair, F. J., Selvan, A. N., Soltani, H., Wilmott, J., & Farrell, T. (2016). Thermal territories of the abdomen after caesarean section birth: infrared thermography and analysis. Journal of wound care, 25(9), 499-512.

Childs, C., Wright, N., Willmott, J., Davies, M., Kilner, K., Ousey, K., … & Stephenson, J. (2019). The surgical wound in infrared: thermographic profiles and early stage test-accuracy to predict surgical site infection in obese women during the first 30 days after caesarean sectionAntimicrobial Resistance & Infection Control8(1), 1-15.

Connolly, T. M., Foppa, C., Kazi, E., Denoya, P. I., & Bergamaschi, R. (2016). Impact of a surgical site infection reduction strategy after colorectal resection. Colorectal Disease, 18(9), 910-918.

Coello, R., Charlett, A., Wilson, J., Ward, V., Pearson, A., & Borriello, P. (2005). Adverse impact of surgical site infections in English hospitals. Journal of Hospital Infection, 60(2), 93-103.

Henriksen, N. A., Meyhoff, C. S., Wetterslev, J., Wille-Jørgensen, P., Rasmussen, L. S., Jorgensen, L. N., & PROXI Trial Group. (2010). Clinical relevance of surgical site infection as defined by the criteria of the Centers for Disease Control and Prevention. Journal of Hospital Infection, 75(3), 173-177.

Horan, T. C., Gaynes, R. P., Martone, W. J., Jarvis, W. R., & Emori, T. G. (1992). CDC definitions of nosocomial surgical site infections, 1992: a modification of CDC definitions of surgical wound infections. Infection Control & Hospital Epidemiology, 13(10), 606-608.

Siah, C. J. R., & Childs, C. (2015). Thermographic mapping of the abdomen in healthy subjects and patients after enterostoma. Journal of wound care, 24(3), 112-120.

Soper, D. E., Bump, R. C., & Hurt, W. G. (1995). Wound infection after abdominal hysterectomy: effect of the depth of subcutaneous tissueAmerican journal of obstetrics and gynecology173(2), 465-471.

Vermillion, S. T., Lamoutte, C., Soper, D. E., & Verdeja, A. (2000). Wound infection after cesarean: effect of subcutaneous tissue thickness. Obstetrics & Gynecology95(6), 923-926.

Zejnullahu, V. A., Isjanovska, R., Sejfija, Z., & Zejnullahu, V. A. (2019). Surgical site infections after cesarean sections at the University Clinical Center of Kosovo: rates, microbiological profile and risk factorsBMC infectious diseases19(1), 1-9.


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Europa Thermohuman ThermoHuman has had the support of the Funds of the European Union and the Community of Madrid through the Operational Programme on Youth Employment. Likewise, ThermoHuman within the framework of the Export Initiation Program of ICEX NEXT, had the support of ICEX and the co-financing of the European Regional Development Fund (ERDF).

CDTI Thermohuman has received funding from the Centre for the Development of Industrial Technology (CDTI), in participation with the European Regional Development Fund (ERDF), for the R+D activities involved in creating a new tool, based on thermography, for the prediction and prevention of rheumatoid arthritis. See project detail.