Comparison 1. All trials analysis.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Incidence of postoperative seroma	18	1252	Risk Ratio (M‐H, Fixed, 95% CI)	1.02 [0.90, 1.16]
1.2 Mean volume of seroma	10	731	Std. Mean Difference (IV, Random, 95% CI)	‐0.25 [‐0.92, 0.42]
1.3 Total volume of drained seroma	13	888	Std. Mean Difference (IV, Random, 95% CI)	‐0.75 [‐1.24, ‐0.26]
1.4 Number of days for persistent drainage	13	861	Std. Mean Difference (IV, Random, 95% CI)	‐0.59 [‐0.95, ‐0.23]
1.5 Surgical site infection	13	1009	Risk Ratio (M‐H, Fixed, 95% CI)	1.05 [0.63, 1.77]
1.6 Postoperative complications	11	981	Risk Ratio (M‐H, Fixed, 95% CI)	1.13 [0.63, 2.04]
1.7 Length of hospital stay	6	364	Std. Mean Difference (IV, Random, 95% CI)	‐0.20 [‐0.78, 0.39]