568 Obstetrics and Gynecology Board Review •••
❍ What is the disadvantage of capacitive coupling?
The energy may be transferred to intraperitoneal tissues such as bowel and cause an inadvertent burn.
❍ How far out can lateral tissue damage occur?
2 to 3 cm for unipolar and 1 to 2 cm for bipolar.
❍ What are the differences between cutting and coagulation currents?
Cutting current provides a constant high-energy waveform.
The coagulation waveform creates an initial high-voltage peak that quickly dissipates and results in desiccation of
the outer layer of the tissue and increased tissue resistance.
❍ Define tissue fulguration, coagulation, and desiccation.
Fulguration means heating the tissue without contacting it. This is beneficial for superficial hemostasis with
minimal tissue penetration.
Coagulation means heating the tissue to the extent that the protein loses its innate configuration and becomes
solid.
Desiccation means that the liquid component of the tissue evaporates and the tissue becomes dry.
❍ What are the major types of lasers used in surgery, and how are they used?
CO 2 , argon, 532-nm potassium-titanyl-phosphate (KTP/532), and neodymium:yttrium-aluminum-garnet
(Nd:YAG).
CO 2 is used mostly for tissue vaporization, whereas KTP and YAG mostly for coagulation.
❍ What preferentially absorbs the energy each laser?
Water preferentially absorbs CO 2 , while hemoglobin and hemosiderin preferentially absorb KTP and YAG.
❍ What is the approximate depth of penetration of CO 2 laser?
Approximately 0.1 to 0.2 mm is achieved.
❍ What are the advantages of using CO 2 laser in laparoscopy?
It cuts quickly, produces very little thermal damage, and can be used for vaporization, coagulation, and excision.
❍ What are the disadvantages of using CO 2 laser in laparoscopy?
Poor hemostasis, cumbersome equipment, too much laser plume produced, difficulty aligning the beam, and
identifying the helium-neon beam.
❍ What is the depth of penetration of argon and KTP lasers?
0.4 to 0.8 mm.
❍ What are the advantages of using fiber-optic lasers in laparoscopy?
Less cumbersome equipment, very accurate targeting, less plume, better hemostasis, smaller channel needed for
fibers, and better visualization against abdominal organs.