Rapid versus stepwise application of negative pressure in vacuum extraction‐assisted vaginal delivery: a multicentre randomised controlled non‐inferiority trial

Please cite this paper as: Suwannachat B, Laopaiboon M, Tonmat S, Siriwachirachai T, Teerapong S, Winiyakul N, Thinkhamrop J, Lumbiganon P. Rapid versus stepwise application of negative pressure in vacuum extraction‐assisted vaginal delivery: a multicentre randomised controlled non‐inferiority trial. BJOG 2011; DOI: 10.1111/j.1471‐0528.2011.02992.x. Objective To evaluate whether the application of rapid negative pressure for vacuum‐assisted delivery is as effective and safe as the stepwise method. Design Randomised controlled trial. Setting Six centres, including university, secondary and tertiary hospitals, in Thailand. Sample In total, 662 women were randomised to rapid and stepwise groups, with 331 women in each group. Methods Vacuum extraction was performed by applying a metal cup (Malmstrom) connected to an electric pump to the fetal head. The stepwise method consisted of four incremental steps of 0.2 kg/cm2 every 2 minutes to obtain a final negative pressure of 0.8 kg/cm2. In the rapid method the negative pressure of 0.8 kg/cm2 was applied in one step in