Method. Numerous protocols have been published, but my preference is to administer 1 intramuscular injection of depot leuprolide acetate (7.5 mg) 6 weeks prior to surgery.
A review of ‘systems’
Submucous myomas have been hysteroscopically removed using the neodymium/yttrium aluminum-garnet (Nd:YAG) laser, a monopolar resectoscope loop, a monopolar radiofrequency (RF) vaporizing electrode, a bipolar RF vaporizing electrode, and a bipolar RF loop.
Laser. The Nd:YAG laser is an expensive device that was popular in the late 1980s and early 1990s. It can be used as a cutting tool for pedunculated Type 0 myomas, or it can be used for myolysis by burning numerous holes in the myoma, causing devascularization and shrinkage.7,8
The sole advantage of the Nd:YAG laser is that it can be used in an isotonic-fluid-filled cavity. Now that accurate fluid-monitoring devices are available, the Nd:YAG laser is rarely used for this indication.
Vaporizing electrodes. Both the bipolar system and monopolar vaporizing electrodes utilize very high RF power (200 W to 300 W) to vaporize fibroids. The advantage is that the fibroids are eradicated very quickly, without any bothersome fibroid chips to remove. The bipolar system can be used with isotonic fluid, whereas the monopolar vaporizing electrodes require non-electrolyte-containing distention media.
The main disadvantages of vaporizing electrodes are:
- They do not produce a tissue sample for pathology. While uterine sarcomas are very rare, they are not homogeneous. Therefore, a simple sample prior to vaporization does not rule out the disease.
- Since vaporizing electrodes are used at high power, numerous gas bubbles are produced and enter the vascular system. Fortunately, these bubbles dissipate rapidly in the blood. As long as the rate of formation does not exceed the rate of dissipation, there are no significant clinical sequelae. The surgeon can avoid complications by monitoring the patient’s endtidal CO2 and maintaining communication with the anesthesiologist. If a sudden drop in endtidal CO2 is observed, the surgeon should stop the case until it resolves.9
Monopolar loop electrode. The instrument most commonly used to remove submucosal myomas is the monopolar loop electrode with a continuous-flow resectoscope. This is quite similar to the instrument used to resect the prostate; it has been slightly modified for gynecologic use to provide enhanced fluid inflow and outflow. A key instrument now considered standard is an accurate fluid-monitoring device that can be attached to the resectoscope.
Distention media for monopolar resection. Prior to the introduction of continuous high-flow resectoscopes and fluid-management systems, monopolar resectoscopy could only be performed using a solution of 32% dextran 70 and water because of that formulation’s viscosity and facilitation of visualization in the presence of blood. However, due to complications related to absorption, allergies, and the solution’s sticky residue, it is not used with today’s high-flow technology.
The instrument most commonly used to remove submucosal myomas is the monopolar loop electrode with a continuous-flow resectoscope.
When using nonviscous fluids with monopolar RF energy, a distention medium without electrolytes must be selected. Isotonic physiologic media such as normal saline or lactated Ringer’s solution would cause the energy at the electrode to disperse, eliminating the cutting effect. Contrary to popular belief, there would be no burning of the uterine cavity and no subsequent danger to the patient.
The 3 most commonly used fluids for uterine distention are 1.5% glycine, 3% sorbitol, and 5% mannitol. All 3 lack electrolytes. The glycine and sorbitol solutions are hypotonic, while 5% mannitol is isotonic. Although there is some debate over whether an isotonic non-electrolyte-containing medium is safer than a hypotonic one, the guidelines for fluid monitoring are the same for all 3.
The goal of a hysteroscopic myomectomy is to alleviate symptoms without causing a weak myometrium or intracavitary synechia. This is accomplished by removing the fibroid without traumatizing normal uterine tissue.
As a general rule, the serum sodium level will decrease approximately 10 meq for every liter absorbed in the blood stream. That is why, to predict hyponatremia, the gynecologist must rely on exact measurements of fluid deficits rather than operating time or total volume used.
Fluid management. Significant hyponatremia can result in pulmonary edema, transient blindness, cerebral edema, brainstem herniation, and death. Catastrophic as these complications are, they are almost 100% avoidable with accurate deficit measurements and adherence to sound fluid-management protocols.
At our institution, fluids are monitored using a weighted system, and the fluid deficit is displayed on the surgical screen in real time. When the deficit reaches 1 L, electrolytes are drawn, the patient is given 10 mg of intravenous (IV) furosemide, and attempts are made to finish the surgery as soon as possible. When the deficit reaches 1.5 L, the surgery is discontinued no matter how much or how little remains to complete it.