Table.

Characteristics of ultrasonographic strategies in patients with suspected deep vein thrombosis

Reference	Diagnostic strategy	No of patients	No (%) with deep vein thrombosis	% with venous thromboembolic complications (95% CI)	Mean No of additional ultrasound tests (or venograms*) required per initially referred patient
Sluzewski et al5	Ultrasonography at days 1, 2, and 7	118	32 (27)	1.3 (0 to 3.9)	1.3
Heijboer et al4	Ultrasonography at days 1, 2, and 8	491	103 (21)	1.5 (0.3 to 2.8)	1.6
Cogo et al7	Ultrasonography at days 1 and 7	1702	408 (24)	0.7 (0.3 to 1.2)	0.8
Birdwell et al6	Ultrasonography at days 1 and 5-7	405	69 (17)	0.6 (0.1 to 2.1)	0.8
Wells et al14	Ultrasonography at day 1 with clinical score†	593	95 (16)	0.6 (0.1 to 1.8)	0.3*
Present study	Ultrasonography at day 1, if normal: d-dimer; repeat ultrasound at 1 week if d-dimer positive	946	265 (28)	0.4 (0.0 to 0.9)	0.1

^*Includes venography in 5.6% of patients. 

^†Low clinical score: normal ultrasonogram (stop), abnormal ultrasonogram (venography); moderate clinical score: normal ultrasonogram (repeat ultrasonography at 1 week), abnormal ultrasonogram (treatment); high clinical score: normal ultrasonogram (venography), abnormal ultrasonogram (treatment).