CHAPTER 156 Endometrial Ablation
Endometrial ablation is safe, effective, efficient, and readily learned. It allows patients to address problematic vaginal bleeding from the endometrium while allowing them to keep their uterus. Methodologies that use hysteroscopy for visualization of the uterus are considered invasive. The newer techniques that do not require the use of hysteroscopy are termed minimally invasive nonhysteroscopic methods for endometrial ablation. This chapter covers the more contemporary approaches to endometrial ablation with a brief historical discussion of the classic techniques of rollerball, hysteroscopic methods of resection, and laser. At the end of the discussion, a table highlighting the U.S. Food and Drug Administration (FDA) comparative data on the five second-generation approaches is provided (Table 156-1). These data reflect the FDA Manufacturer and User Facility Device Experience (MAUDE) database review.
TABLE 156-1 Comparative Data from 2001 U.S. Food and Drug Administration Trial of Five Second-Generation Endometrial Ablation Devices
Advantages
• Performed in outpatient facility (rollerball and thermal balloon ablation) or office (cryoablation)
• Highly effective in controlling or eliminating associated symptoms (e.g., premenstrual syndrome, dysmenorrhea, moodiness)
Indications
• Menorrhagia or heavy menstrual bleeding (defined as blood loss >80 mL/cycle; bleeding for longer than 8 days; blood loss or symptoms that interfere with normal activities; or blood loss sufficient to cause anemia)
Prerequisite Conditions
• Absence of any precancerous or cancerous lesions of the endometrium or cervix; normal Papanicolaou (Pap) smear and negative endometrial biopsy or hysteroscopy.
• Uterine size less than 12 weeks of gestation and uterine cavity less than 12 cm in length (with the cryoablation technique, large uterine size does not preclude performing the procedure).
• Other potential causes of excessive menstrual bleeding that could be treated medically or by other alternative forms of surgery have been excluded.
Contraindications
Absolute
• Previous uterine surgeries such as myomectomy, classic cesarean section (excluding low transverse cesarean section), or any uterine surgery that would render the myometrium thin (e.g., deep myomectomy)
Relative
• Uterine size greater than 12 cm (this may vary depending on the procedural approach of the surgeon).
• Unusual anatomic variation that may preclude adequate ablation, such as congenital uterine abnormalities. If there is a septate or bicornuate uterus, both cavities must be ablated separately; in the case of hydrothermablation, this may constitute a relative contraindication. Clinical consideration and procedural approach must be taken into account before proceeding with the ablation procedure of choice.
Equipment and Supplies
• For hysteroscopy-based ablation, a rigid (0-, 12-, or 30-degree viewing angle) hysteroscopic resectoscope (Fig. 156-1)
• Uterine distention system (CO2 or fluid) for hysteroscopy-based systems (see Chapter 140, Hysteroscopy)
• Energy source and ablative attachments (laser or cautery, thermal balloon, and cryosurgical ablation techniques do not require these components)
Preprocedure Patient Education and Forms
Endometrial ablation is such a life-altering procedure that it is the surgeon’s obligation to provide the patient with all of the information needed to understand all of the possible outcomes (see the example patient education form online at www.expertconsult.com). Some key elements of discussion are to emphasize that ablation may induce sterility but does not guarantee that pregnancy will not occur. Another element is that sexual desire should not be affected by the procedure. Because the endometrium is the only focus of treatment, and not the ovaries, hormonal cycles will continue if the patient is premenopausal.
Preprocedure Patient Preparation
• In most instances, the patient will have already had endometrial sampling performed in the investigation of her abnormal bleeding. If this has not been done, endometrial sampling should be performed in advance of the procedure to verify the absence of malignant or premalignant lesions.
• Preoperative ultrasonography is helpful to ascertain the endometrial thickness and assess the uterine anatomy. The ideal thickness of the endometrium for ablation is less than 3 to 4 mm. There are several ways to reach this goal:
• Physiologically, the late menstrual or early proliferative phase of the cycle will provide the ideal setting for proceeding without the use of pharmacologic agents.
• To produce an atrophic, thin endometrium before the surgery, pharmacologic agents may be used. This will allow for more efficient ablation and lessen bleeding to decrease postoperative anemia. Agents available are either antiestrogenics such as danazol (600 to 800 mg daily for 3 to 12 weeks) or gonadotropin-releasing hormone (GnRH) agonists such as leuprolide acetate (two 3.75-mg intramuscular injections administered 3 to 4 weeks before surgery) or goserelin (3.6 mg injected subcutaneously 3 to 4 weeks before surgery). Pharmacologic preparation is not required with use of the NovaSure.
• Laminaria tent placement the day before the procedure will enhance cervical dilation. However, care must be taken to limit cervical dilation owing to concerns regarding the seal that the cervix can provide during the procedure, as in the case of the hydrothermablation procedure or the NovaSure.
Procedure
Anesthesia
The anesthesia provided for the rollerball and laser procedures is usually general anesthesia, but with the new procedural approaches, paracervical block along with oral analgesics may be all that is required to effect adequate clinical comfort. The paracervical block is used in several of the new techniques (see Chapter 173, Paracervical Block).
Technique of Hysteroscopic Endometrial Ablation with Rollerball
A rigid (0-, 12-, or 30-degree viewing angle) hysteroscopic resectoscope (see Fig. 156-1) is necessary for this procedure.
Procedure
1 Insert bivalve speculum to expose the the cervix. Another alternative would be to place a weighted speculum in the posterior vaginal cavity and use an anterior retractor to expose the cervix, thus maximizing exposure of the cervix.
3 Gently sound the uterus with a uterine sound. The tenaculum can be used to provide uterine stability.
4 Use Hegar dilators to gradually dilate the cervix (usually 8 to 12 mm to provide enough width to advance the resectoscope component of the hysteroscope). Also be careful to not overdilate the cervix because this may induce leakage of distention media, thus limiting the view. If this does occur, a fine-tooth tenaculum may be used to approximate the loose cervical edges.
5 Assemble the resectoscope, making sure the advance and retraction capability is in order. (There is a paradoxical mechanism in all resectoscopes. Pulling the trigger advances the rollerball and gently relaxing pressure retracts the rollerball. The pushing and pulling of the trigger creates the extension/retraction of the rollerball, which effects the rowlike destruction of the endometrium. The rollerball is a spherical or barrel-shaped electrode that rolls over the endometrium at a speed of 10 to 15 mm/sec [Fig. 156-2]).
6 Insert the resectoscope by gentle advancement under direct visualization, following the lumen, with the irrigating fluid flowing (very similar to advancing a rigid sigmoidoscope).
8 Gently advance the rollerball by pulling the trigger until it approximates the proximal segment of the internal os. About 1.5 cm below (distal to) the internal os, set the end-point line of demarcation for ablation. Cauterize the entire circumference of this area by placing the rollerball directly on the segment by gently maneuvering the resectoscope. This creates a ringlike area of destruction that marks the eventual end point for the rollerball retraction.
9 Activate the cautery source by the foot pedal, set to a coagulating power of 50 to 80 W. There are differing viewpoints on the average power. Some operators use up to 200 W. There are also recommendations to start at 60 W to destroy the endometrial tissue for the first layer of endometrial destruction, followed by an increase to 80 to 100 W for subsequent passes. Visualize the entire distended uterine fundus and then start ablating the fundus by contacting the rollerball with the fundal tissue in a right-to-left manner. When performing ablation on the fundus, the rollerball is extended to near its maximum. The rollerball “paints” the fundus in a right-to-left manner in rows until the fundal area is entirely ablated. The ostia are handled in a similar fashion. However, because the ostial area is spherical, the rollerball must be rotated within the resectoscope to contact the tissue, consistent with the anatomy being ablated. After the line of demarcation has been established at the internal os, the corpus is ablated with the rollerball fully extended, starting at the fundus at around 6 o’clock. Advance the rollerball to the fundus to ablate the entire fundal and periostial area. Gently advance the rollerball to full or nearly full extension to the fundus, then retract in a linear fashion while activating the energy source to destroy the endometrium. A count of “one thousand one, one thousand two, one thousand three” should be used to effect a subjective but fairly accurate time for contact of the rollerball with the tissue during the ablation process. Continue this in a row-by-row fashion, destroying 360 degrees around the entire endometrial cavity two to three times, ending once again at 6 o’clock position.
10 On completion of the procedure, check the fluid balance to confirm minimal risk of postoperative fluid overload.
Complications
• Absorption of excess amounts of hypotonic distending solution results in increased central venous pressure and hyponatremia that, if untreated, lead to pulmonary edema, hypotension, cerebral edema, and potentially fatal cardiovascular collapse. To avoid these complications, intraoperative fluid use must be strictly monitored during the procedure and the patient observed for signs and symptoms of fluid overload. Most physicians will stop a hysteroscopic procedure at a 1- to 1.5-L fluid deficit when using glycine, sorbitol, or mannitol to avoid hyponatremic hypovolemia. A lower threshold may be required for older patients or those with preexisting cardiovascular problems. Dextran 70 has been associated with fluid overload, pulmonary edema, intravascular coagulopathy, renal insufficiency or failure, rhabdomyolysis, and anaphylactoid reactions. Glycine can result in hyperammonemic encephalopathy and transient blurred vision and blindness.
• Mechanical complications include air embolism, cervical laceration, perforation of the uterus, and severe hemorrhage.
• Endometrial cancer may persist if occult presence is not diagnosed before the ablation, making diagnosis afterward very difficult.
• Pregnancy, although rare, is possible. With a very thin post-treatment endometrium, there is a higher risk of ectopic pregnancy as well as poorly sustained placenta and embryonic implantation.
Endometrial Laser Ablation
A resective hysteroscope with Nd:YAG laser attachment is necessary for this procedure.
Procedure
2 The rigid hysteroscope is placed, and the endometrium is visualized. The laser attachment is placed through the operating channel of the hysteroscope and activated at a power level of approximately 60 to 80 W delivered by a 600-µm bare quartz fiber.
3 There are two techniques used for endometrial laser ablation, the touch or drag technique and the nontouch or blanching technique. During the touch technique, the laser tip is lightly applied to the endometrial surface and gently swept across the uterine cavity. For the nontouch technique, the laser tip is brought within 1 to 5 mm of the endometrial surface but does not touch it. Compared with the touch technique, this technique reduces the potential for fluid absorption because the blood and lymphatic vessels are coagulated as opposed to being cut open. Some physicians use a combination of the two techniques. Ablation begins at the cornual and fundal areas with the delivery of short, 5- to 10-second bursts of laser energy. The anterior wall is ablated to the level of the cervical os, followed by ablation of the lateral and posterior walls.
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