Langer 2003.

Study characteristics
Methods	Study design: prospective randomised controlled trial Randomisation technique: random allocation Allocation concealment: inadequate Inclusion criteria: well explained Exclusion criteria: well explained Lost to follow‐up: not reported Baseline variables: matching between both limbs of the trial Intention‐to‐treat analysis: not reported Sample size calculations (power of the study): not reported
Participants	Country: USA Number of participants: FG: 26 and NFG: 29 Mean age (years): FG 60.8 ± 7.3; NFG 56.3 ± 11.8
Interventions	FG: Tisseel® was applied under skin flaps following breast and axillary surgery Types of surgical intervention: modified radical mastectomy sector mastectomy axillary dissection Confounding interventions: reduced shoulder mobilisation
Outcomes	Primary: incidence of seroma Secondary: drainage days total seroma volume wound infection
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Participants were allocated randomly to both arms of the trial
Allocation concealment (selection bias)	High risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not reported
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	High risk	Not reported
Selective reporting (reporting bias)	Low risk	No
Other bias	Low risk	Inclusion, exclusion criteria, ethics approval and conflict of interest declaration was adequately reported.