Study	Reason for exclusion
Ansaloni 2001	Alternate allocation, not randomised.
Ayers 1987	Treatment allocation based on hospital number.
Ayres‐de‐Campos 2000	Not enough data provided in abstract for assessment.
Behrens 1997	Not enough data provided in abstract for assessment.
Bjorklund 2000	Comparison of abdominal incisions along with different combinations of other steps of surgery.
Dani 1998	Comparison of abdominal incisions along with different combinations of other steps of surgery.
Darj 1999	Comparison of abdominal incisions along with different combinations of other steps of surgery.
Decavalas 1997	Not enough data provided in abstract for assessment.
Direnzo 2001	Not enough data provided in abstract for assessment.
Falls 1958	Not a randomised controlled trial.
Ferrari 2001	Comparison of abdominal incisions along with different combinations of other steps of surgery.
Franchi 1998	Comparison of abdominal incisions along with different combinations of other steps of surgery.
Gaucherand 2001	Treatment allocation by year of birth.
Hagen 1999	Not enough data provided in abstract for assessment.
Heimann 2000	Comparison of abdominal incisions along with different combinations of other steps of surgery.
Hohlagschwandtner	Not a comparison of abdominal incisions.
Mahawerawat 2010	Not a comparison of abdominal incisions.
Meyer 1997	Not enough data provided in abstract for assessment.
Meyer 1998	Not enough data provided in abstract for assessment.
Moreira 2002	Comparison of abdominal incisions along with different combinations of other steps of surgery.
Oguz 1998	Not a comparison of abdominal incisions
Redlich 2001	Treatment allocation by first letter of surname.
Wallin 1999	Comparison of abdominal incisions along with different combinations of other steps of surgery.
Xavier 1999	Not enough data provided in abstract for assessment.