There are several surgical tools designed to remove (ablate) tissue and control any bleeding that results. Each tool has its own set of operating characteristics. The surgical tools that remove, destroy, incise and coagulate tissue include

(1) scalpels and scissors,

• a variety of blade sizes and shapes as well as scissor sizes and shapes are available.

• the knife is ideal for cutting the skin, with research documenting greater tensile strength and faster healing in skin cut with a knife as compared to the carbon dioxide laser, harmonic scalpel or electrosurgical devices.

• scissors are ideal instruments for dissection of tissue and can also be used effectively to cut tissues ranging from tough to filmy. These instruments can be used to remove tissue on which endometriosis has grown. Excised tissue will include some normal tissue and any bleeding created needs to be controlled. This has limited the use of these instruments in the routine treatment of endometriosis.
  

(2) electrosurgical devices,

• these can be adjusted to provide different amounts of power (20 to 80 watts is usually used) with different blends of cutting and coagulation. The electrical generator has variable power (wattage) settings. Pure cutting is a continuous delivery of undamped electrical energy so that a relatively low voltage is required to achieve a particular chosen power (wattage) usage. Pure coagulation is an interrupted or damped delivery of electrical energy such that current is flowing less than 10% of the time (it flows only 6% of the time) so that a much greater peak voltage is required to achieve the same chosen power (wattage) use (compared to cutting). Blends of cutting and coagulation allow the surgeon to select the relative degree of damping used. In the rare situations in which I use cautery to cut (such as during hysteroscopic surgery) I typically use blend 1 which applies current 80% of the time and gives just a little coagulation as compared to pure cutting.

• a wide range of effects is possible. Pure cutting current has little char (which acts to coagulate). At the other end of the spectrum, fulgaration produces a superficial layer of char by holding the electrode a small distance from the tissue and allowing the current to spark. Lateral thermal damage with these instruments due to heating of surrounding tissue limits their use in the ablation of endometriosis, especially when close to other vital structures.
  

(3) thermocoagulation devices,

• these differ from electrocoagulation devices in that they do not deliver high frequency electrical current to generate heat in the tissues.

• these devices deliver heat directly via a hot metal tip that is applied to tissue.

• these devices are adjusted to deliver heat at up to 160 degrees centigrade, and tissue generally turns white when desiccation causes coagulation.

• of course it is necessary to avoid inadvertently touching tissues other than those desired while using this tool and during its cool down period.

• this is an ideal coagulating device but extensive lateral thermal damage has limited its use in the treatment of endometriotic lesions that are close to other vital structures.
  

(4) lasers,

• these devices can deliver fine beams of intense energy to tissue with the power density (watts per square centimeter) at the tissue site determining the effect (vaporization, excision, coagulation).

• there are different laser systems. These include fiber delivery via KTP-532 or Nd:YAG lasers where the energy released from the tip of the fiber diverges to dissipate the energy (highest power density is closest to the tip of the laser fiber). The carbon dioxide (CO2) laser focuses the laser energy with a series of mirrors into differing size spots that help to determine the power density at the tissue.

• the CO2 lasers can deliver power in different wave forms that determine the power density achieved and amount of lateral thermal damage. The most common laser in use for most fertility work during laparoscopy is the CO2 laser and the optimal wave form for fertility work is the ultrapulse wave. There are noticeable differences in the effects produced by the lasers that are currently available.

1. Laser is a precise and efficient method of destroying tissue. Laser light can be focused into a very narrow beam of photons since the waves of light that are produced are coherent (each wave is "in phase" as it travels through time and space), monochromatic (each wave has an identical wavelength), and collimated (the waves are parallel to one another). When the laser light is absorbed into tissue, the tissue heats up and may be damaged.
   
2. When tissue is heated to greater than 100 degrees centigrade (C) the water within the cells vaporizes and the cells burst (the conversion of liquid water to steam results in a 1000 fold increase in volume) to result in tissue separation. If the tissue is heated to greater than 57 C the proteins within the cells that are necessary for cellular function are irreversibly denatured and these proteins no longer function (the cell dies). If the tissue is heated to greater than 45 C there is swelling (edema) and frequently eventual cell death.
   
3. The goal of laser laparoscopy for fertility work is to remove or vaporize abnormal tissue while leaving as much of the adjacent normal tissue intact. To accomplish this goal, the duration of the transmitted laser energy can be manipulated. Continuous laser energy may be applied to tissue but this results in considerable thermal heating and damage to surrounding tissue (similar to cautery). Superpulse and ultrapulse laser settings transmit short pulses of laser energy with long interpulse intervals to limit the spread of thermal damage to surrounding normal tissue (by enhancing interpulse tissue cooling) and produce highly precise areas of tissue vaporization. This allows the surgeon to destroy the abnormal tissue while minimizing thermal damage to the surrounding normal tissue.
   

(5) the harmonic scalpel, and

• this is a device that incorporates a tip that vibrates at an ultrasonic frequency to rapidly denature proteins and separate tissue with little generated heat.

• conceptually, this is a great tool for ablation of endometriosis and lysis of adhesions.

• experience with the harmonic scalpel has not yet led to widespread acceptance of this tool. Additionally, the results seen on second look laparoscopy several weeks following its use have had mixed findings.
  

(6) the cavitron ultrasonic surgical aspirator (CUSA),

• this is widely used for tumor debulking by gynecologic oncologists. It has a vibrating tip that reacts to an alternating electromagnetic field (alternates 23,000 times per second) and produces significant heat such that cooling is provided by saline liquid solution sprayed over the tip at a rate of 3-10 ml per minute. This is not commonly used for treatment of endometriosis.