Technique of hysteroscopy

Gas hysteroscopy

Expanding environment

In gas hysteroscopy, carbon dioxide is used to expand the uterine cavity. Rubin was the first to report the use of CO ₂ in hysteroscopy in 1925. A hysteroflator is used to deliver gas into the uterine cavity. When performing diagnostic hysteroscopy, sufficient pressure in the uterine cavity is 40-50 mm Hg, and the gas flow rate is more than 50-60 ml/min. The most important indicator is the gas supply rate. When gas is supplied at a rate of 50-60 ml/min, even its entry into a vein is not dangerous, since carbon dioxide is easily dissolved in the blood. When the CO ₂ supply rate is more than 400 ml/min, acidosis occurs, therefore the toxic effect of CO ₂ manifests itself in the form of cardiac dysfunction, and when the gas supply rate is 1000 ml/min, death occurs (Lindemann et al., 1976; Galliant, 1983). At pressures above 100 mm Hg and _CO2 flow rates above 100 ml/min, cases of gas embolism have been reported. Therefore, it is unacceptable to use a laparoscopic insufflator or any other devices not intended for hysteroscopy to deliver gas into the uterine cavity. This may result in uncontrolled high-speed gas delivery and cause the complications described above.

Diagnostic hysteroscopy usually takes a few minutes, and the small amount of gas that enters the abdominal cavity is usually quickly absorbed without causing any complications. Sometimes, if the fallopian tubes are well-patented, gas enters the abdominal cavity, which may cause slight pain in the right shoulder, which resolves on its own after a while. Gas hysteroscopy is easy to perform and provides a very good view of the uterine cavity, especially in postmenopausal patients and in the proliferative phase of the menstrual cycle. If there is blood in the uterine cavity, CO ₂ causes bubbles to form, limiting the view. In such a situation, it is necessary to switch to liquid hysteroscopy.

CO2 does not support combustion, _so it can be safely used in electrosurgery, as was done at the stage of introducing hysteroscopic sterilization by coagulation of the orifices of the fallopian tubes.

However, for long-term operations, carbon dioxide is unacceptable, as it does not provide adequate conditions due to significant leakage through the fallopian tubes, cervical canal and surgical canal.

In addition, gas hysteroscopy is not recommended for cervical deformities, when it is impossible to create sufficient tightness and achieve full expansion of the uterine cavity, and when trying to use adapter cervical caps, there is a risk of cervical injury. When the myometrium is invaded by a cancerous tumor, hermetically sealing the cervix with an adapter can contribute to rupture of the uterine body even with insignificant gas pressure.

Due to the possible risk of gas embolism, CO2 _is not used for curettage of the uterine cavity. The disadvantages of gas hysteroscopy also include difficulties in acquiring _CO2.

The use of carbon dioxide is advisable when performing diagnostic hysteroscopy and in the absence of bloody discharge.

Thus, gas hysteroscopy has the following disadvantages:

1. Impossibility of performing surgical interventions in the uterine cavity.
2. Impossibility of performing hysteroscopy in case of uterine bleeding.
3. Risk of gas embolism.
4. High cost.

Technique

When performing gas hysteroscopy, it is better not to dilate the cervical canal, but if necessary, Hegar dilators up to No. 6-7 are inserted into the cervical canal.

Depending on the size of the cervix, an adapter cap of the appropriate size is selected. A Hegar dilator up to No. 6-7 is inserted into the adapter channel, with the help of which (after removing the bullet forceps from the cervix) the cap is put on the cervix and fixed on it by creating negative pressure in the cap using a special syringe or vacuum suction.

After removing the dilator from the adapter cannula, the hysteroscope body without the optical tube is inserted into the uterine cavity. 40-50 ml of isotonic sodium chloride solution is introduced into the uterine cavity through the body channel (to flush the uterine cavity of blood), then the solution is removed using suction.

_{A light guide is connected to the optical tube of the hysteroscope, the optics are fixed to the body of the hysteroscope. A tube for the flow of CO2} from the hysteroflator at a rate of 50-60 ml/min is connected to one of the valves in the body, while the pressure in the uterine cavity should not exceed 40-50 mm Hg.

Liquid hysteroscopy

Expanding environment

Most surgeons prefer liquid hysteroscopy. With sufficiently clear visibility, liquid hysteroscopy allows easy monitoring of the course of hysteroscopic operations.

The fluid is supplied to the uterine cavity under a certain pressure. Too low a pressure will impair visibility, preventing adequate expansion of the uterine cavity and tamponade of damaged vessels. Too high a pressure will provide excellent visibility, but the fluid will enter the circulatory system under pressure with the risk of significant fluid overload and metabolic disorders. Therefore, it is desirable to control the pressure in the uterine cavity at a level of 40-100 mm Hg. Measuring intrauterine pressure is desirable, but not necessary.

The fluid flowing through the outflow valve or the dilated cervical canal must be collected and its volume must be measured continuously. Fluid losses should not exceed 1500 ml. During diagnostic hysteroscopy, these losses usually do not exceed 100-150 ml, during minor operations - 500 ml. When the uterus is perforated, fluid loss immediately increases sharply, it stops flowing through the valve or the cervix, remaining in the abdominal cavity.

A distinction is made between high- and low-molecular fluids for expanding the uterine cavity.

High-molecular-weight fluids: 32% dextran (giscon) and 70% dextrose. They maintain the necessary distension of the uterine cavity, do not mix with blood and provide a good overview. Even 10-20 ml of such a solution injected into the uterine cavity with a syringe is enough to provide a clear overview. However, high-molecular-weight solutions are quite expensive and very viscous, which creates difficulties in work. Careful cleaning and rinsing of instruments is necessary to avoid blockage of the taps for the supply and outflow of liquid when these solutions dry out. The most significant disadvantage of these media is the possibility of anaphylactic reaction and coagulopathy. If hysteroscopy is delayed, dextran can enter the abdominal cavity and, having been absorbed into the vascular bed due to its hyperosmolar properties, cause its overload, which can lead to pulmonary edema or DIC syndrome. Cleary et al. (1985) showed in their studies that for every 100 ml of high-molecular dextran that enters the vascular bed, the volume of circulating blood increases by 800 ml. In addition, the absorption of these solutions from the abdominal cavity occurs slowly and reaches a peak only by the 3rd-4th day.

Due to all these shortcomings, high-molecular liquid media are currently used extremely rarely, and in some countries (for example, in the UK) their use in hysteroscopy is prohibited.

Low-molecular solutions: distilled water, physiological solution, Ringer's and Hartmann's solutions, 1.5% glycine solution, 3 and 5% sorbitol solution, 5% glucose solution, mannitol. These are the main dilating media used in modern hysteroscopy.

1. Distilled water can be used for diagnostic and operative hysteroscopy, short-term manipulations and operations. It is important to know that when more than 500 ml of distilled water is absorbed into the vascular bed, the risk of intravascular hemolysis, hemoglobinuria and, consequently, renal failure increases.
2. Physiological solution, Ringer's and Hartmann's solutions are available and cheap media. These liquids are isotonic to blood plasma and are easily removed from the vascular system without causing serious problems. Isotonic solutions are successfully used during hysteroscopy against the background of uterine bleeding, as they easily dissolve in blood, wash out blood and fragments of excised tissue from the uterine cavity, and provide fairly good visibility. These solutions are unacceptable in electrosurgery due to their electrical conductivity, and are recommended only for diagnostic hysteroscopy, operations with mechanical tissue dissection, and laser surgery.
3. For electrosurgical operations, non-electrolyte solutions of glycine, sorbitol and mannitol are used. It is permissible to use a 5% glucose solution, rheopolyglucin and polyglucin. They are quite cheap and accessible, but their use requires careful monitoring of the volume of fluid introduced and removed. The difference should not exceed 1500-2000 ml to avoid a significant increase in the volume of circulating blood, leading to electrolyte disturbances, pulmonary and cerebral edema.
   • Glycine is a 1.5% solution of the amino acid glycine, its use was first described in 1948 (Nesbit and Glickman). When absorbed, glycine is metabolized and excreted from the body by the kidneys and liver. Therefore, glycine is prescribed with caution in cases of liver and kidney dysfunction. Cases of dilutional hyponatremia have been described both with transurethral resection of the prostate gland and with intrauterine resectoscopy.
   • 5% sorbitol, 5% glucose - isotonic solutions, easily mixed with blood, provide fairly good visibility, are quickly eliminated from the body. If a large amount of these solutions enters the vascular bed, hyponatremia and postoperative hyperglycemia are possible.
   • Mannitol is a hypertonic solution that has a strong diuretic effect, mainly removing sodium and very little potassium. As a result, mannitol can cause significant electrolyte disturbances and pulmonary edema.

Thus, liquid media used to expand the uterine cavity have the following disadvantages:

• Reduction of the field of view by 30°.
• Increased risk of infectious complications.
• Risk of anaphylactic shock, pulmonary edema, coagulopathy when using high molecular weight solutions.
• Possibility of overload of the vascular bed with all the ensuing consequences.

Technique

When performing liquid hysteroscopy using various mechanical devices for fluid delivery, it is advisable to maximally expand the cervical canal for better fluid outflow (Hegar dilators up to No. 11-12).

When using a system with a constant supply and outflow of fluid and an operating hysteroscope (Continuous flow), it is advisable to expand the cervical canal to No. 9-9.5.

The telescope is placed in the hysteroscope body and secured with a locking clasp. A flexible light guide with a light source, a conductor connecting the device to the medium for dilating the uterine cavity, and a video camera are attached to the hysteroscope. Before inserting the hysteroscope into the uterine cavity, the supply of fluid intended for dilating the uterine cavity is checked, the light source is turned on, and the camera is focused.

The hysteroscope is inserted into the cervical canal and gradually advanced inside under visual control. The time required for sufficient expansion of the uterine cavity is waited for. The orifices of the fallopian tubes serve as landmarks to ensure that the hysteroscope is in the cavity. If gas bubbles or blood interfere with the examination, it is necessary to wait a little until the outflowing fluid carries them out.

It is best to first insert the hysteroscope with the inflow valve half open and the outflow valve fully open. If necessary, these valves can be partially closed or fully opened to regulate the degree of distension of the uterine cavity and improve visibility.

All walls of the uterine cavity, the area of the mouths of the fallopian tubes, and the cervical canal at the exit are carefully examined one by one. During the examination, it is necessary to pay attention to the color and thickness of the endometrium, its correspondence to the day of the menstrual-ovarian cycle, the shape and size of the uterine cavity, the presence of pathological formations and inclusions, the relief of the walls, the condition of the mouths of the fallopian tubes.

If focal pathology of the endometrium is detected, a targeted biopsy is performed using biopsy forceps inserted through the surgical channel of the hysteroscope. If there is no focal pathology, the telescope is removed from the uterus and separate diagnostic curettage of the uterine mucosa is performed. Curettage can be mechanical or vacuum.

The main causes of poor visibility may be gas bubbles, blood, and insufficient lighting. When using liquid hysteroscopy, it is necessary to carefully monitor the fluid supply system to avoid the entry of air under pressure, and to maintain an optimal flow rate of fluid to wash the uterine cavity from blood.

Microhysteroscopy

Currently, two types of Hamou microhysteroscope are known - I and II. Their characteristics were presented above.

Microhysteroscope I is an original multi-purpose instrument. It can be used to examine the uterine mucosa both macro- and microscopically. Macroscopically, the mucosa is examined using a panoramic view, and microscopic examination of cells is performed using the contact method after intravital cell staining.

First, a standard panoramic examination is performed, with special attention paid to, if possible, atraumatic passage through the cervical canal under constant visual control.

Gradually advancing the hysteroscope, the mucous membrane of the cervical canal is examined, then the entire uterine cavity is panoramically examined, rotating the endoscope. If atypical changes in the endometrium are suspected, the direct eyepiece is replaced with a lateral one and a panoramic examination of the mucous membrane of the uterine cavity is performed with 20-fold magnification. With this magnification, it is possible to assess the density of the glandular structures of the endometrium, as well as the presence or absence of dystrophic and other changes, the nature of the location of the vessels. With the same magnification, a detailed examination of the mucous membrane of the cervical canal is performed, especially its distal section (cervicoscopy). Then microcolpohysteroscopy is performed.

The first stage of examination of the cervix using a microhysteroscope (20x magnification) is colposcopy. Then the cervix is treated with a solution of methylene blue. The magnification is changed to 60x and a microscopic examination is carried out with a direct eyepiece by touching its distal end to the tissues of the cervix. The image is focused with a screw. This magnification allows one to examine cellular structures and identify atypical areas. Particular attention is paid to the transformation zone.

The second stage of microcolposcopy is an examination of the cervix with an image magnification of 150 times, examination at the cellular level. The examination is carried out through a side eyepiece, the distal end is pressed against the epithelium. With such magnification, only pathological areas are examined (for example, proliferation zones).

The technique of microcolpohysteroscopy is quite complicated and requires extensive experience not so much in hysteroscopy as in cytology and histology. The complexity of image evaluation also lies in the fact that the cells are examined after intravital staining. For the reasons listed, microhysteroscope I and microcolpohysteroscopy have not found wide application.

Microhysteroscope II is widely used in operative hysteroscopy. This model allows for panoramic examination of the uterine cavity without magnification, macrohysteroscopy with 20x magnification and microhysteroscopy with 80x magnification. The application technique is the same as described above. Using microhysteroscope II, operative hysteroscopic interventions are performed using semi-rigid and rigid surgical endoscopic instruments. In addition, a resectoscope is used with the same telescope.

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