A trocar is a versatile medical instrument usually inserted through a hollow tube called a cannula that functions as a portal into the body of a surgical patient. The purpose of a trocar is the introduction of three essential elements: illumination, a viewing scope and surgical tools. The miniaturized modern laparoscopic trocar can accommodate all three, and more, as a single piece of surgical equipment.
Although a patent for the trocar was recorded in the early 19th century, given that its original use was primarily to relieve the pressure of built-up bodily fluids or gasses, it is surmised that the tool in principle, if not sophistication, has been in use for possibly thousands of years. The sharply pointed puncturing device, so named for its positionally triangular three sides, was first used to view the inside body of a dog in 1905. Its aid in the surgery of a human a few years later ushered in a new age of medicine — non-invasive surgical repair of internal injuries.
The first laparoscopic equipment was quite crude in comparison to the modern laparoscopic trocar. The surgeon peered into a straight-shafted scoping device made with blurry glass lenses into a dark enclosure barely made visible by stray ambient light. Modern advances in camera and video technology, and in fiber optics, have taken the laparscope directly to a surgical target where it is illuminated by cold halogen or xenon light. Electronic technology has miniaturized these elements. Miniaturization has also been applied to design a myriad of surgical tools, such as scissors, retractors and staplers, which can be easily attached to or inserted through a laparoscopic trocar.
The trocar itself has not only miniaturized but also advanced in functional design. Resembling a long, metallic syringe, they are no longer triangular or sharpened at the tip. Most are equipped with irrigation and suction tubes. The thumb and forefinger controls provide greater range of tool manipulation. One of the techniques of laparotomy is to separate the abdominal organs and create a roomier surgical space by inflating the body cavity with carbon dioxide, and the laparoscopic trocar has therefore been redesigned to be a completely sealed instrument.
Laparotomies, or "open" surgeries of the abdominal cavity, are still necessary, but increasingly, the laparoscopic trocar is enabling operations to be performed through an incision of less than 0.4 inches (1 cm), the diameter of this surgical instrument. In the case of surgery of human joints, the incision and inserted trocar is even smaller. Such laparoscopic surgeries have thus been dubbed "keyhole" surgery.
In practice, most surgeries require using multiple laparoscopic trocars through several keyhole incisions. Some operating procedures involve more than one instrument, and some instruments require two hands to manipulate. Both technological miniaturization and design refinements, however, have progressed toward a device for single-incision laparoscopic surgeries.