Table 3.

Quality assessment of the studies according to QUADAS-2.

	Risk of Bias				Feasibility
First Author	Patient’s Selection	Index Test	Reference Standard	Flow and Timing	Patient’s Selection	Index Test	Reference Standard
Krysiak	Low	Low	Low	Low	Low	Low	Low
Metso	Low	Unclear	Low	Low	Low	Low	Low
Mainardi	Low	Unclear	Unclear	Low	Low	Unclear	Low
Valentino	High	Unclear	Unclear	Low	Low	Unclear	Low

The studies by Asamoah [16] and Stramazzo [18] are not included in this quality assessment as they are a case report and letter to editor, respectively.