Sensitivity

Specificity

PPV

NPV

Accuracy

Ultrasound finding

1. B-mode ultrasound

72.2%

(26/36)

88.3%

(83/94)

70.3%

(26/37)

89.2%

(83/93)

83.8%

(109/130)

2. Color Doppler ultrasound

65.8%

(25/38)

86.9%

(80/92)

67.6%

(25/37)

86%

(80/93)

80.8%

(105/130)

3. Increased PSV ≥ two-fold relative to the proximal segment

79.2%

(19/24)

83%

(88/106)

51.3%

(19/37)

94.6%

(88/93)

82.3%

(107/130)

4. Monophasic flow

and broadening spectrum at the examined segment

59%

(25/42)

86.3%

(76/88)

67.6%

(25/37)

81.7%

(76/93)

77.7%

(101/130)

5. Monophasic flow with reduced velocity at the distal segment

40%

(4/10)

86.8%

(66/76)

28.6%

(4/14)

91.7%

(66/72)

81.4%

(70/86)

Combining two ultrasound findings

1 + 2

86.4%

(19/22)

83.3%

(90/108)

51.3%

(19/37)

96.8%

(90/93)

83.8%

(109/130)

1 + 3

94.7%

(18/19)

82.9%

(92/111)

48.6%

(18/37)

98.9%

(92/93)

84.6%

(110/130)

1 + 4

85.7%

(18/21)

82.6%

(90/109)

48.6%

(18/37)

96.8%

(90/93)

83.1%

(108/130)

2 + 3

94.4%

(17/18)

82.1%

(92/112)

45.9%

(17/37)

98.9%

(92/93)

83.8%

(109/130)

2 + 4

81.8%

(18/22)

82.4%

(89/108)

48.6%

(18/37)

95.7%

(89/93)

82.3%

(107/130)

Combining three ultrasound findings

1 + 2 + 3

93.7%

(15/16)

96.8%

(92/95)

40.5%

(15/37)

98.9%

(92/93)

82.3%

(107/130)

1 + 2 + 4

93.3%

(14/15)

79.8%

(91/114)

37.8%

(14/37)

97.8%

(91/93)

80.8%

(105/130)