Twelve RCTs were included (n= 1,153 patients). Sample size ranged from 33 to 200. Seven trials reported adequate methods and timing of randomisation. One trial reported blinding of the clinical assessor; three trials reported patient blinding. Six trials reported sample size calculation. Ten trials reported no withdrawals or crossovers to the alternative intervention. Four trials reported power analysis on an intention-to-treat basis.
Harmonic scalpel versus other haemostatic methods: Use of the harmonic scalpel was associated with a significant reduction in mean operating time (WMD -22.67 minutes, 95% CI -29.98 to -17.37; I2=87%), blood loss (WMD -20.03 mL, 95% CI -27.83 to -12.22; I2=62%), postoperative pain (WMD -0.86 points, 95% CI -1.60 to -0.13; I2=77%) and length of hospital stay (WMD -0.12 days, 95% CI -0.25 to -0.00; I2=0%). There was no significant difference between harmonic scalpel and other methods in the volume of drainage fluid or complications.
Harmonic scalpel versus classic suture ligation (three RCTs: Use of the harmonic scalpel was associated with a significant reduction in mean operating time compared with class suture ligation (WMD -17.56 minutes, 95% CI -20.73 to -14.39; three RCTs; I2=6%). One trial reported a reduction in length of stay in the harmonic scalpel group. There was no significant difference between harmonic scalpel and classic suture ligation in blood loss or complications.
Harmonic scalpel versus suture or clip ligation combined with electrocauterisation (nine RCTs): Use of the harmonic scalpel was associated with a significant reduction in mean operating time (WMD -23.41 minutes, 95% CI -31.1 to -15.7; nine RCTs; I2=91%), blood loss (WMD -24.23 mL, 95% CI -34.4 to -14.1; five studies, I2=56%), postoperative pain (WMD -0.86 points, 95% CI -1.60 to -0.13; three RCTs, I2=77%) and a non significant reduction in length of stay (WMD -0.12 days, 95% CI -0.26 to 0.01; I2=0%). There was no significant difference between interventions in volume of drainage fluid or complications.
Harmonic scalpel versus electrothermal bipolar vessel sealing system (one RCT): Use of the harmonic scalpel was associated with a significant reduction in mean operating time (WMD -35 minutes, 95% CI -46.1 to -23.9) and blood loss (WMD -14 mL, 95% CI -24.8 to -3.2). There was no significant difference between interventions in complications.
The funnel plot was asymmetrical suggesting the possibility of publication bias.