Study	Reason for exclusion
Black 1989	Not a randomized controlled trial.
Black 2003	Not a randomized controlled trial since treatment group was based on patient preference for date of operation.
Chen 2004	Compared two no‐scalpel methods.
Chen 2005	Duplicate publication of Chen 2004; compared two no‐scalpel methods.
Nirapathpongporn 1990	Not a randomized controlled trial.
Song 2006	Compared no‐scalpel method with intra‐vas device.