Diagnostic efficacy, imaging characteristics, and detection accuracy of transabdominal superficial ultrasonography for various types of appendicitis

Table 4 Comparison of diagnostic efficacy of two ultrasonography methods for acute gangrenous appendicitis

Diagnostic method	Nature	Gold standard (units)		Sensitivity (%)	Specificity (%)	Accuracy (%)	Positive predictive value (%)	Negative predictive value (%)
		Positive	Negative
Conventional abdominal ultrasonography	Positive	15	8	62.50	83.33	76.39	65.22	81.63
	Negative	9	40
Transabdominal superficial ultrasonography	Positive	23	1	95.83	97.92	97.22	85.83	97.92
	Negative	1	47
χ2	-	-	-	8.084	6.008	13.642	7.111	6.954
P value	-	-	-	0.004	0.014	< 0.001	0.008	0.008