Six RCTs (n=1,066) were included.
Four studies were defined as using intention-to-treat analysis.
There was no significant difference between patients in the subcutaneous drainage group compared with the no drainage group for wound disruption (OR 0.74, 95% CI: 0.39, 1.42, p=0.36; 6 studies), infection (OR 1.15, 95% CI: 0.70, 1.90, p=0.58; 6 studies), haematoma (OR 1.05, 95% CI: 0.33, 3.30, p=0.94; 4 studies) or seroma (OR 0.44, 95% CI: 0.14, 1.43, p=0.17; 4 studies). Significant heterogeneity (p<0.05) was found for analyses of wound disruption and seroma; random-effects models were used for these analyses.
Analysis limited to studies that compared drainage with no drainage showed a significant reduction in the risk of seroma formation with subcutaneous drainage (OR 0.28, 95% CI: 0.11, 0.74, p=0.01; 3 studies), but no significant difference between treatments for other outcomes.