Table 1.

Observational studies on emergency use of ultrasound for detection of necrotizing fasciitis

Author, year, country	Patient group	Study type	Ultrasound machine	Outcomes	Key results
Yen et al. 2002 (Taiwan) [11]	62 patients with limb infection, 17 confirmed necrotizing fasciitis	Prospective observational	Unspecified brand linear-array transducer (7.5-MHz)	Diagnostic accuracy of ultrasonography for necrotizing fasciitis	Sensitivity: 88.2%, Specificity: 93.3%, Positive predictive value: 83%, Negative predictive value: 95.4%
Lin et al. 2019, (Taiwan) [7]	95 patients with limb infection, 48 confirmed necrotizing fasciitis	Retrospective with prospective enrolment	Philips Clear Vue 550, Philips Healthcare, Bothell, WA, USA. Equipped with linear transducer (4–12 MHz)	Diagnostic accuracy of ultrasonography for necrotizing fasciitis	Sensitivity: 75%, Specificity: 70.2%, Positive Predictive value: 71.7%, Negative predictive value:72.7%, Ultrasound findings of fluid accumulation of 2 mm in fascia have the best accuracy of 72.7%, as shown in Fig. 2
Lahham et al. 2022 (USA) [12]	64 patients with soft-tissue infections	Prospective observational	Mindray TE7 ultrasound machine with a linear transducer (5–16 MHz)	Diagnostic accuracy of ultrasonography for necrotizing fasciitis	Sensitivity:100%, Specificity:98.2% Positive predictive value:88.9% Negative predictive value:100%