[Spiral trocar--a new trocar concept].

Introduction: We would like to introduce a new trocar technique for minimal invasive surgery. The new trocar is a spiral whose coil becomes ever increasingly stronger towards the centre. Because of this, there is a smooth transition between spiral, screw and rod. The outer diameter remains the same. The spiral-trocar is screwed through the abdominal wall like a corkscrew. Because of this, the primary channel of puncture runs spirally. Furthermore, the channel is dilated and centralised so that the trocar's rod together with its sleeve can be pushed through the abdominal wall. This trocar design demonstrates the following advantages: The trocar can be screwed through the abdominal wall in a controlled manner without having to apply axial pressure. This prevents any unintentional perforation of organs. Because different layers of the tissue are penetrated at different places, they overlap, thus sealing one another after removal of the sleeve. The puncture channel was minimal, thus leaving very little risk of trocar site hernia.

Methods: The spiral-trocar was examined and compared with other types of trocars in vivo and vitro.

Results: During these tests, the spiral-trocar demonstrated a high level of safety and good usability.

Discussion: The spiral-trocar is an easily cleanable, reusable product without a mechanical sealing device and can be used together with most sleeves. This makes it very cost effective.