Which Needle in which Trocar? A Mathematical-Theoretical Approach

Abstract

Aim-Background: Needles used in surgery come in various sizes and shapes, and with varying properties. In lapa-roscopic surgery, the trocars create the communication ports to the operative environment, and these ports are used for the introduction of instruments into the surgical field. Needles also need to be passed through these cannulas, which creates constraints regarding the needle size. The aim of this study was to describe the correlation between trocar size and needle size/shape. Methods: In order to estimate the maximum needle length that can be introduced through trocars of different calibers, we approached this problem from the mathematical and theoretical perspective, based on the four most commonly used needle types and the six most frequently used trocars. Results: The results are summarized in a table which determines the maximum needle length the surgeon may choose, given the specific needle type and trocar. Conclusions: Introduction of needles into the abdomen through laparoscopic trocars poses the risk of needle distortion or trocar dysfunction. In order to avoid these complications, the type and length of the needle to be introduced should be compatible with the diameter of the trocar.