POCUS superior modality for diagnosing Necrotizing fasciitis

It is already known that NF is deadly, and diagnosing it remains challenging. Any delay in diagnosis increases the risk of mortality, rapid rate of tissue necrosis and higher chances of sepsis.

The skin signs can be subtle in the early course of the disease, while marked redness and bullae suggest a more advanced disease.

History, physical, and Laboratory Risk Indicators for Necrotizing Fasciitis are not very sensitive.

The use of POCUS is widely increasing for the diagnosis of skin and soft tissue infections. It is even faster and more safe compared to CT.

Against the above background, a study was conducted by a team of researchers led by Amy Marks to determine POCUS accuracy for diagnosing NF. The researchers included two prospective studies and one retrospective. The study outcomes were sensitivity and specificity.

The study summary includes the following:

• The database searched were PubMed, Scopus, CINAHL, LILACS, the Cochrane databases, Google Scholar, and bibliographies of selected articles.
• QUADAS-2 tool was used to determine quality analyses.
• The researchers identified three papers, including 221 patients with a mean age of 57.
• 33% of patients had NF.
• True positive rate: 33% (73 of 221 patients).
• The sensitivity range was 85.4%–100%.
• The specificity range was 44.7% to 98.2%.
• The most sensitive was Fluid accumulation along the fascial plane, 85.4 %.
• The most specific was subcutaneous emphysema, 100%.

To conclude, POCUS has good sensitivity and specificity for diagnosing NF.

The study’s limitations were few studies, study differences prevented meta-analysis, all studies used convenience samples, raising the risk for selection bias and blinding was poorly reported.

Further reading:

Marks, Amy, et al. “Ultrasound for the Diagnosis of Necrotizing Fasciitis: A Systematic Review of the Literature.” The American Journal of Emergency Medicine, vol. 65, Elsevier BV, Mar. 2023, pp. 31–35. Crossref, https://doi.org/10.1016/j.ajem.2022.12.037.