Twelve studies met the inclusion criteria (n=2,398, range 41 to 826). Six studies were small, prospective and reported sufficient details of the tests, but were not blinded; these were considered high quality as they passed 55% or more of the quality criteria.
Colour Doppler ultrasonography had a sensitivity of 87% (95% CI 84% to 90%), specificity of 89% (95% CI 87% to 90%) and diagnostic odds ratio of 125 (95% CI 55 to 285) when the cutoff of borderline or malignant (positive test) versus benign (negative test) was used; significant heterogeneity was observed for all three analyses (p=0.001 and I2=65% or over). The area under the SROC curve was 0.9573 (standard error 0.0181). No threshold effect was detected (Spearman correlation coefficient 0.042, p=0.897).
The estimates did not alter significantly when high-quality studies were pooled separately. Funnel plots showed evidence of publication bias.