Parks et al. (2007) Trocar-less instrumentation for laparoscopy: magnetic positioning of intra-abdominal camera and retractor. Ann Surg 245: 379–384

The degrees of freedom and working envelope of conventional laparoscopic instrumentation are limited, which often necessitates the use of multiple trocars to improve visibility and efficiency at the expense of reduced cosmesis and an increased risk of complications.

Parks et al. developed a transabdominal magnetic anchoring and guidance system (MAGS)—a pair of external permanent magnets, two types of retractor (sling and paddle types) and a camera, each with permanent magnets attached to their base—to see whether the number of trocars required can be reduced. The instruments are introduced through a single standard 12 mm trocar, positioned intra-abdominally, and anchored in place by the external permanent magnets, which are placed on the abdomen. A 12 mm trocar customized with fiberoptic cables and coupled to a conventional light source provides illumination.

In a pig model, the MAGS prototype anchored the instruments in place across an abdominal wall thickness of 1.5 cm. There was no loss of coupling when the instruments were moved around and the camera could be moved to virtually any location in the peritoneum. The authors completed two nonsurvival pig nephrectomies using only two trocars, without complications.

Laparoscopy with magnetically anchored instruments introduced through a single trocar is, therefore, feasible and could revolutionize surgical practice. Several clinical and engineering limitations (e.g. reduced magnetic attraction across thick tissues) must, however, be addressed before widespread adoption of this MAGS for humans is possible.