Triple non-invasive diagnostic test for exclusion of common bile ducts stones before laparoscopic cholecystectomy

Table 5 Diagnostic value of each of the triple tests, alone and in combination n (%)

Variables	Sensitivity	Specificity	NPV	PPV
1. Medical history	44	92.5	90.5	38.1
2. Ultrasound	64	97.1	95	76.2
3. Alkaline phosphatase ≥ 400 Ul/L	32	95	90	26.7
4. Serum bilirubin ≥ 1.5 dL/L	30.3	76.2	89.2	25
2 + 3 + 4	80	82.9	96.7	40
2 + 3 or 2 + 4	32	97.1	90.9	61.5
2 + 1+ 3 or 4	84	81.7	97.3	39.6

NPV: Negative predictive value; PPV: Positive predictive value.