Minimally Invasive Non-Hysteroscopic Endometrial Ablation
Minimally invasive non-hysteroscopic techniques have largely replaced hysteroscopic endometrial ablation. The reasons for the gynecologist’s preference for these minimally invasive procedures relate to the following: minimal skill required, no distension medium needed, and rapid performance time expected. The results of these minimally invasive ablations have been generally good if one uses a final common path of reduced or normal bleeding. Amenorrhea rates are generally lower than with direct vision hysteroscopic endometrial ablation. Disadvantages of the minimally invasive techniques include that the techniques are mainly blind (the exception being the hydrothermablator [HTA] device), and they typically rely on low intrauterine volume and pressure to ensure safety.
The more commonly used devices are described below.
Hydrothermablator (Boston Scientific, Natick, MA) (Fig. 110–1A, B). A modified hysteroscope is placed into the uterine cavity. A bag of normal saline serves as a reservoir, and the entire system is fluid filled. The uterine cavity is distended, and any leaks are detected by drops in the reservoir. The saline is heated outside of the uterus and is flushed through the uterine cavity at low pressure. The ablation can be directly viewed via the telescope.
Microsulis (microwave endometrial ablation; Microsulis, Hampshire, UK) (Fig. 110–2). This electrosurgical device consists of a monopolar probe, which functions as a microwave because the radiofrequency generator delivers frequency in the megahertz operational range. The endometrium is ablated via conversion of electrical to thermal energy. This is one of the oldest non-hysteroscopic devices, dating back to 1991. High power outputs (e.g., 200 watts) are required to maintain a constant probe temperature of 65°C. The probe is rotated intraoperatively to obtain even dispersal of heat. The patient must wear a large neutral electrode throughout the procedure.
NovaSure (Hologic Inc., Marlborough, MA) (Fig. 110–3A, B). Consists of a bipolar mesh bag, which is inserted into the uterus collapsed via an applicator. The device must be oriented so that the kitelike frame can accommodate to the inverted triangular uterine cavity. A dial that reads the cavity width and depth is obtained from a device display. Carbon dioxide gas pressurizes the cavity to determine whether leakage is or is not occurring. Radiofrequency biopolar electrical energy coagulates the endometrium at 180 watts of output.
Thermachoice (Gynecare-Ethicon, Somerville, NJ) (Fig. 110–4
