宫腔镜子宫内膜切除术（图文演示）

HYSTEROSCOPIC   ENDOMETRIAL   ABLATION
Authors
H Fernandez
Abstract
The description of the hysteroscopic endometrial ablation covers all aspects of the surgical procedure used for the management of endometrial pathologies and menometrorrhagia.
Operating room set up, position of patient and equipment, instruments used are thoroughly described. The technical key steps of the surgical procedure are presented in a step by step way: adjustment of system, operative technique.
Consequently, this operating technique is well standardized for the management of this condition.



中文版：宫腔镜子宫内膜切除术（中文图文演示）

1. Introduction
Operative hysteroscopy (Neuwirth, 1978) has modified the surgical management of benign uterine neoplasms. The first endo-uterine procedures using a resectoscope were performed for uterine malformations and submucosal myomas. Endometrial pathologies subsequently became indications for use of the resectoscope (endometrial ablation).
In endometrial ablation, all or most of the endometrium is removed. The procedure is combined with the destruction of the superficial layer of the myometrium. It is performed under visual guidance/control. Six to eight millimetres of thein thickness of the endometrium is resected or destroyed. This resection includes the base of the glands and the internal longitudinal layer of the myometrium, and preserves the external circular layer and its venous plexus. Endometrial ablation is an interesting alternative to hysterectomy in menorrhagias that are resistant to medical therapy during the perimenopausal period.

2. Anatomy
• Anatomy of the endometrium

1. Internal longitudinal layer
2. External circular layer
3. Functional endometrium
4. Venous plexus
To determine the edges of the resection, knowledge of the anatomy of the endometrium is essential.

• Pathophysiology

1. Round ligament
2. Uterine tube
3. Fundus of uterus
4. Proper ovarian ligament
5. Uterine cavity
6. Endometrium
7. Myometrium
8. Mesometrium of broad ligament
9. Uterine artery
10. Ureter
11. Cervical canal
12. Uterosacral ligament
13. External uterine opening
14. Vagina
In women of childbearing age, abnormal uterine bleeding can be linked to local or systemic abnormalities. These abnormalities can be secondary to organic pathologies of the uterine cavity, such as the presence of polyps, fibroids or endometrial hyperplasia, all of which alter the hemostatic mechanism of the endometrium. In the absence of these pathologies, uterine bleeding is defined as functional.

3. Indications
Indications
Hysteroscopic endometrial ablation is indicated for functional bleeding when medical therapy (progestogens, anti-hemorrhagic treatment) fails or is contraindicated. This endoscopic procedure is only indicated only for women who do no longer want to become pregnant, because the mucosal destruction that is produced seriously compromises any subsequent possibility of conception. Nevertheless, it should not be considered as being a permanent contraceptive procedure and patients should be advised to continue to useusing protective measures.

Goal of the procedure
The goal of the procedure is to avoid a hysterectomy for a functional pathology. The resection technique is either complete with a high rate of resulting amenorrhea or hypomenorrhea, or partial with preservation of the isthmus. In the latter case, the patient’s menstrual cycles are preserved. The indication for one technique overas opposed to the other is more a sociological and behavioral issue than a medical one.

Contraindications
- atypical or malignant endometrial lesion detected during diagnostic hysteroscopy;
- a large uterus of a large size, which often leads to failure of the technique;
- contraindications to anesthesia.

4. Preoperative workup

The preoperative workup should give a complete diagnosis of the intercavity pathololgy (submucous leiomyoma, polyp) or myometrial pathology (interstitial fibroid, adenomyosis) that can account for the abnormal bleeding. It should also ensure that there is no suspicious lesion. The workup includes a pelvic (preferably endo-vaginal) ultrasonography and a diagnostic hysteroscopy with biopsy of the endometrium. The hysteroscopy may be performed in an outpatient setting before determining a surgical indication or as the first step of the surgical procedure. It verifies the regularity of the mucosa, ruling out the presence of a malignant endometrial lesion. If the findings are abnormal, a biopsy is performed and the indication is modified.
A preoperative treatment of GnRH agonists (Gonadotropin Releasing Hormone) can be administered to prepare the endometrium. However, no studies have proven that this treatment improves long-term results.

5. Operating room
• Patient

- general anesthesia, local-regional anesthesia or paracervical block anesthesia;
- lithotomy position: legs spread at a 45° angle, thighs at a 90° angle from the surface of the table and knees bent at a 90° angle;
- perineal and cervicovaginal preparation;
- urinary catheter (optional).

• Team

1. The surgeon is seated between the patient's legs.
2. The assistant stands to the right of the surgeon.
3. The anesthesiologist is at the patient's head.

• Equipment

1. Hysteroscopic unit and monitor
2. High-frequency electrosurgical generator
3. Instrument table
4. Operating table
5. Anesthetic unit
Equipment placed to the surgeon's left:
- endocamera and monitor;
- devices to control pressure and flow of distension media: a constant uterine distension must be maintained. The pressure is controlled continually by suction and irrigation pumps;
- standard or specifically adapted tubing for each type of pump;
- distension medium: glycocolle is the medium most commonly used with monopolar cautery. With bipolar cautery, saline is used (to lower the risk of metabolic complications);
- light source: the same type of Xenon light source is used for diagnostic hysteroscopy, surgical hysteroscopy and laparoscopy;
- high frequency electrosurgical generator: unipolar electrosurgery uses high-frequency current (>300 000 Hz). Division of tissues is performed with an unmodulated current that produces a rapid rise in temperature. In bipolar electrosurgery, the operating channel is 24 French. ''Spray'' and ''desiccation'' modes exist. The maximum power used by the generators is 200 W.

6. Instruments

Usual equipment:
1. Hegar's dilators (No. 1 to No. 10, diameter increasing from 0.5 to 1 mm);
2. Speculum with detachable valves;
3. Resection electrode (4 mm) ending with a 90° cutting loop (7 to 9 mm) for monopolar hysteroscopy, or a 90° 24 French cutting loop or a 5 French tip for bipolar hysteroscopy;
4. rigid endoscope between 2.7 and 4 mm in diameter; the direction of view normally used in hysteroscopy is 12°.
5. Resectoscope: from 7 to 9 mm with two channels, one internal (irrigation) and one external (suction) for monopolar hysteroscopy, or from 5 to 9 mm with two channels and a double current operation channel for bipolar hysteroscopy. In all cases it has an operative handle: passive (electrode in) or active (electrode out);
6. Hysteroscope;
7. Irrigation and suction channels;
8. Two Pozzi graspers;
9. Hysterometer.

7. Adjustment of system
Monopolar system
The resection techniques described use monopolar current. The suction-irrigation pump must be preset to maintain an intrauterine pressure <=100 mm Hg, a 250 mL/s flow rate, a 0.2 bar suction pressure and 45 W of power. The procedure must not last longer than 45 minutes. The total volume of glycocolle used must be limited to 6 L. Precise monitoring of the distension liquid inflow and outflow must be done, and the procedure must be stopped immediately if there is a difference between the irrigation and suction flow rates (a 500 mL difference is acceptable). If there is too much of a difference, or if the procedure lasts too long, a chemistry panel must be performed immediately after the procedure to check for a metabolic complication (hyponatremia).

Bipolar system
Bipolar spray electrosurgery is a more recent system. Its efficacy seems to be equivalent to monopolar electrosurgery, with a decrease in morbidity. The suction-irrigation pump should be preset to maintain a flow of 150 mL/s, a pressure of 80 mm Hg and 100 W of power. There are no limits to the duration of the procedure.

8. Operative technique
&#8226; Dilation of the cervix


Bimanual examination is performed to evaluate the position of the uterus before dilation. This lowers the risk of perforation. A speculum with detachable valves is inserted and the cervix is grasped with 2 Pozzi or Museu-Palmer graspers placed in a 3 o’clock and 9 o’clock position to bring the uterus into an intermediary position. The procedure routinely begins with a diagnostic hysteroscopy if this was not done during the preoperative evaluation. The cervix is then dilated with Hegar’s dilators, using progressively larger dilators until a No. 10 dilator can be inserted.

&#8226; Inserting the resectoscope

The endocamera, the resectoscope and the electrode are then assembled and connected to the Xenon light source, the hysteroscopic unit, the electrosurgical generator and the suction-irrigation tubing. Care must be taken to remove all air bubbles from the tubing. The resectoscope is then introduced under videoscopic guidance.

&#8226; Resection technique

The resection is usually begun on the posterior surface, creating a groove from the fundus of the uterus to the isthmus with a regular, continuous, flexing motion of the arm. The initial groove is used to determine how deep the resection must be, stopping on the muscular wall whose limits are defined by the external circular fibers of the myometrium, before the venous plexus layer. Classically, the resection of the endometrium is completed in a clockwise direction, and includes the posterior surface, the left edge, the anterior surface and the right edge. The margins of the isthmic portion of the uterus must be preserved due to the proximity of the uterine vessels. The endocervical portion must not be resected, to avoid endocervical adhesions that can lead to pain.

&#8226; End of procedure

The hysteroscope is then removed and the loop resection electrode is replaced by a Rollerball coagulation electrode equipped with a metal ball that rotates on an axis. This ensures a homogeneous coagulation. As the uterine wall is thinner at the level of the ostia, and because of the difficulty involved in resecting the fundus of the uterus, it may be easier to begin the procedure by coagulating the 2 ostia and the fundus of the uterus.
During the resection of the endometrium, hemostasis is performed as needed with elective coagulation of the vessels. At the end of the procedure, irregularities of the uterine wall must be eliminated. These irregularities are left in place until the end of the procedure to be used as anatomical landmarks.
In partial endometrial ablation, 1 cm of the supra-isthmic endometrial cuff is left in place. The shavings of the endometrium are collected for histologic examination using the loop or a blunt dissector. Preferably, the shavings are not removed as they are resected, but pushed towards the bottom of the cavity and removed at the end of the procedure.
When endometrectomies are performed for post-menopausal patients or on a small uterus (hysterometry <=6 cm), the shavings must be removed regularly throughout the procedure.

9. Complications
Mechanical complications
Uterine perforation occurs either during dilation of the cervix or during the resection. There is a risk of visceral burns if the perforation is not detected. To prevent perforation during dilation of the cervix, it is advisable to facilitate cervical dilation in nulliparous patients (2 tablets of misoprostol administered the evening before surgery). The use of intermediary-sized Hegar's dilators (eg 7.5, 8.5) can also be helpful. Prevention of perforation during resection is dependent on the surgeon's compliance to certain operative rules. Constant good visualization is mandatory. In addition, it is recommended to continually extract the shavings of the endometrium as they are resected, rather than push them towards the bottom of the cavity.

Bleeding complications
Bleeding is usually minimal and stops after a few hours. Prevention of bleeding correlates to the prevention of perforations. More serious bleeding complications may occur, and the need to resort to hysterectomy has been reported in several studies (Overton et al., 1997). To prevent this complication, hemostasis of the divided vessels must be carefully performed as required during the procedure.

Postoperative infection
Post-hysteroscopic endometritis occurs in 1% to 5% of cases (McCausland, 1993), justifying the systematic use of intraoperative prophylactic antibiotics (cephalosporin).

Metabolic complications
Transurethral resection syndrome was first described by urologists (Averous et al., 1981). It is the result of the intravascular passage of a significant quantity of irrigation fluid, and can lead to hemodilution. In serious cases, a combination of circulatory signs are present that can lead to shock, pulmonary edema, kidney failure and neurological disturbances including somnolence and convulsions. Preventive measures are dependent on adherence to procedural protocol, the most important of which is a meticulous monitoring of the inflow and outflow of fluids.