The hallmark of a successful hysteroscopist is decided by his choice of equipment used for the procedure. The decision regarding the type and quality of instruments is based on various criteria such as optical clarity, durability, performance of allied parts (such as sheaths, scissors and forceps), costs, and upgradeability of the instruments as also after sales service provided by the company.
The instrumentation consists of:
- Light cable
- Light source
- Recording devices
- Distention systems
- Mechanical operating systems
- Electrosurgical sources
- Ancillary instruments
Hysteroscopes are available in different sizes, and flexibility.
The outer diameter (OD) indicates the width of the barrel including the sheath. This in the modern day flexible hysteroscopes could be as less as 1.2 mm. Modern rigid hysteroscopes range from 2.7-10 mm; the OD of a diagnostic scope typically ranges from 2.7-5.0 mm, while the OD of an operative sheath ranges from 5-10 mm.
The Rigid Hysteroscope
The Standard Rigid 4 mm (Hopkins Hysteroscope)
The standard used rigid hysteroscope is 4 mm with a 5 mm diagnostic sheath. This scope provides a very good image. It is available with varying directions of view: 0, 12 or 30 degrees. Normally a 30 degree scope is used for diagnosis while a 12 degree scope is used for operative work such as endometrial resection. However a 30 degree scope can also be used for resection.
In case of operative procedures the 4 mm scope needs to be combined with an operative sheath with a diameter of 7.0 to 8.5 mm, necessitating anesthesia and cervical dilatation.
The Mini Rigid 2.9 mm /1.9 mm Office Hysteroscope
In order to overcome the shortcomings of a standard 4 mm scope, there have evolved two systems that can be effectively utilized for diagnostic and operative hysteroscopy, either in an outpatient office setting or an inpatient hospital setting. With these systems it is possible to perform operative procedures such as polypectomy (polyps <4cm diameter), adhesiolysis, tubal cannulations, and myomectomies (myomas <2cm) in an office setting.
- The Standard Bettocchi hysteroscope (Karl Storz): This hysteroscope with Hopkins based rods lens system is a miniature version of the famous Hamou-2 microhysteroscope. The scope has an external diameter of 2.9 mm. It can be used as a panoramic hysteroscope (1x) as well as a micro contact hysteroscope (80x). The scope is also available without the microhysteroscopic attachment (commonly used by the author). For diagnostic purposes, it can be used with a single flow outer sheath of 3.6 mm or a continuous flow outer sheath of 4.4 mm.In case of operative hysterscopy it can be combined with a continuous flow operative sheath of 3.9 mm x 5.9 mm (average diameter 5mm). This sheath has an operative channel to accommodate 5 French instruments to pass through for operative purpose.
- The modified Bettocchi: This is a new version with a 1.9 mm diameter optic along with corresponding decreased diameters of diagnostic and operative sheath.
- The semi rigid Versascope system (Johnson and Johnson - Gynecare division): The versascope is a flexible telescope made up of a set of 50,000 fused optical fibres, providing a zero degree field of vision with an outer panoramic angle view of 75 degrees. The scope has an external diameter of 1.8 mm. and length of 28 cm. The density and optical quality of the image system produces an image, which is similar to the conventional rod lens panoramic hysteroscope. Unlike the rigid scopes, the versascope has got a disposable sheath. It is used with a continuous flow diagnostic cum operative sheath, which has an outer diameter of 3.5 mm and a distal curvature of 10 degrees. A proximal collar is provided. This can be rotated through 360 degrees. This allows manipulation of the scope for full peripheral viewing, without disturbing the instrument position. The operative channel has an expandable instrument channel which can easily accommodate instruments till 7 French in diameter. This operative channel also simultaneously functions as an independent outflow port for continuous flow during the procedure. The hysteroscope comes with a fibreoptic cable.
The Flexible Hysterofibroscopes
The flexible 1.2 mm hysteroscope can be easily passed into the uterine cavity without dilatation. However it is very fragile and generates a small image. Neither does it allow any degree of operative work to be performed. The operative instruments are very fine with diameters of less than 2mm. They are extremely costly and very delicate. The hysteroscope can be used for diagnosis as well as fine operative procedures such as embryo transfer. They are not that commonly used in practice.
The hysteroscope usually includes the telescope and the sheath that encases it. (Newer diagnostic models, however, may lack the sheath). Outer sheaths have accessory channels that enable the inflow and outflow of the distention media. When applicable, the sheath and a separate connecting bridge also have ports to insert operative and manipulating instruments.
The diameter of the sheaths is based on the type of scope used.
- Versascope sheath: This is a disposable sheath having a continuous flow inflow and outflow channel. This 3.5 mm sheath can be used for both diagnostic as well as operative procedures. This enables it to have good distention and good vision. It also has an operating cannel through which one can pass 2mm diameter instruments such as versapoint electrodes (twizzle, spring, ball) or forceps.
- Sheath for 2.9 mm Bettochi scope:
- Single flow 3.6 mm diagnostic sheath
- Continuous flow 3.6 mm inner sheath along with 4.4 mm outer sheath for diagnostic hysteroscopy.
- Single flow 4.3 mm operating sheath which has got a channel for introducing 2mm operating instruments
- Continuous flow 4.3 mm inner sheath along with 5 mm outer sheath for diagnostic as well as all operative procedures. This combination is the best to have.
- Recently there is a new smaller diameter resectoscope sheaths with inner and outer cannels along with smaller diameter electrodes (Loop, ball, cylinder and knife) which can be used with the 2.9 mm Bettochi scope.
- Sheaths for the 4 mm standard hysteroscope:
- Single flow sheath for diagnosis
- Continous flow with inner and outer sheath for diagnosis.
- Continuous flow inner and outer sheath for operative purpose along with operative channel.
- Standard 26 mm resectoscope with inner sheath, outer sheath, working element, electrodes for using unipolar current.
- Standard 26 mm resectoscope (Gynecare Jonson) with inner sheath, outer sheath, working element and Bipolar electrodes to be used with versapoint bipolar current. It is important to note that this sheath has to be used with standard 2.9 mm or 4 mm Hopkins rigid hysteroscope. It cannot be combined with the versascope.
- Standard fibreoptic cable to be used with Hopkins endoscopes and cold light source or xenon light source. The cable is normally 5 mm in diameter and 180 cm in length.
- Special fused fibre light cable to be used with versascope. This cable can be attached to any type of light source with special adaptors. It is important to note that one has to exclusively use this cable in combination with versacope.
There are various light sources, which one can use for illumination:
- Halogen: This 150 watt to 250 w cold light source is sufficient for vision. However it tends to give of a reddish tinge to the image.
- Xenon: A 175 watts xenon light source provides an outstanding illumination and enables a good depth of field. Although the light is extremely hot at its source, most of the heat gets dissipated along the length of the fibreoptic cable. Despite this, a significant amount of heat can be generated at the distal tip. This can cause thermal injury to the patient or burn paper drapes or clothing with prolonged contact. Hence, one should keep the intensity of the light as less as possible.
ENDOSCOPIC CAMERA AND MONITOR
In office hysteroscopy, the image size when seen by the operators’ eye directly via the eyepiece is quite small. Hence it is preferable to use digital cameras with zoom systems that are attached to the eyepiece and transmit appropriately magnified images to a visual monitoring screen. A single chip endoscopic camera is sufficient for diagnostic and minor operative work. A three chip camera will not be of additional help, unless it has additional filters to eliminate the pixelisation and digitalization of the image.
The technical criteria of a good camera are:
- Good Resolution : Based on the number of lines or pixels
- High Sensitivity : Based on the lux
- High quality of video output/images
- Good signal to noise ratio
- Easy sterilization system.
- Digital recording on CD Or DVD
One can use high resolution Sony monitors or digitalized flat screen computer monitors for good clarity. One can also use the newer generation flat screen televisions to cut costs.
Fluid Distention Systems
There are various distention systems that can be used. These are:
- Pressure Cuff
- Total Input output system
Of these the endomat is the ideal system especially for office hysteroscopy purposes, as it correctly maintains intrauterine pressure to around 40 to 50 mm of Hg, thus preventing peritoneal reflux and resultant discomfort. However the endomat is very costly and a simple pressure cuff in conjunction with low intensity outflow suction can do the trick.
Gas Distention Systems
One can use a Co2 hysteroflator. Care should be taken, not to use laparoscopic pneumo insufflator for distending the uterine cavity as this can lead to death on table.
Normally, the uterine walls are in apposition and it requires distention of the true uterine cavity for the purpose of detection of any intrauterine pathology by a hysteroscope. Hence various distention media are available for the purpose of creating a cavity by overcoming the myometrial resistance. It also creates sufficient pressures, which prevents bleeding that occurs during operative hysteroscopy.
Types of Media
The different types of media available are as follows:
- Gas: CO2 gas
- Low viscosity fluids:
- Electrolyte / Ionic
- Non electrolyte / Non – ionic
- High viscosity fluids
Carbon-dioxide (CO2) Gas
CO2 gas is highly diffusible and soluble, allowing continuous elimination of small quantities of intravasated gas by the lungs. It requires electronic machines, which measures the intrauterine gas pressure and also the gas delivery flow rate.
Most hysteroscopic examination can be performed at a flow rate of approximately 30 – 40 ml/min with an intrauterine pressure at approximately 60-70 mm Hg. These two parameters are inversely proportional to each other and thus compensate each other to maintain proper balance.
- Provides clean medium
- Permits excellent visualization, as there is no interposition of a substance to cause refraction.
- Provides adequately maintained distention of the uterine cavity.
- When mixed with blood, it may produce bubbling which is cumbersome and may obscure view. It may rarely lead to gas embolism and death.
- Specific machines are necessitated for electronic calibration of CO2 flow rate and pressure.
- Laser use is cumbersome, as the smoke and fumes cannot be easily evacuated without deflating the uterine cavity.
However it remains the best distention media for diagnostic hysteroscopy with smaller diameter hysteroscopes.
LOW VISCOSITY FLUIDS
Low viscosity fluids are mainly used during operative hysteroscopy as they permit uterine cavity lavage of the blood clots and tissue debris formed during the operation.
Electrolytes/Ionic Distention Media
The most commonly used ionic media are:
- Normal saline (0.9% NaCL i.e. sodium chloride)
- 5% Dextrose
- 50% Saline (0.45% NaCL)
- Ringer's lactate solution.
- The presence of electrolytes makes the operation somewhat safer by preventing hyponatremia, should excessive amount of fluid by used and absorbed.
- Inexpensive and readily available.
- Normal saline is iso-osmolal (at 280 mOsm/L) and metabolically inert.
- Solution for use with Bipolar Electrosurgery.
- Volumes overload from excessive intravasation (> 2.5 litres) of media. This can cause left heart failure and pulmonary edema (non-cardiogenic origin)
- Available in one liter plastic bags and requires pumps.
- Hence the quantity of fluid used should be carefully monitored.
- Contraindicated for monopolar electrosurgery.
Non Electrolytes/Non – ionic Distention Media
Available solutions are,
- 3% Sorbitol (sugar solution, metabolizes into fructose and glucose)
- 1.5% Glycine (mixture of amino acids, metabolizes into ammonia, urea and oxalate)
- 5% Mannitol (sugar solution, osmotic diuretic and minimal metabolism)
- Combination of Sorbitol 2.8% and Mannitol 0.5%.Most of these fluids are available in 3 liters plastic containers.
- Inexpensive and readily available.
- When attached to large bore tubing, and elevated to approximately 80cm, enough pressure is obtained to distend the uterine cavity by gravity and does not require any tourniquets or pumps.
- It's a media of choice for monopolar resectoscopic surgery, because there are no electrolytes to disperse the current, and impede the electrosurgical effect.
- Both Sorbitol and Glycine solution are hypo-osmolar and are readily metabolized by specific pathways. The remaining surplus of free water in the intravascular tree can manifest itself as fluid overload, symptomatic hypo-osmolar hyponatremia.
- Associated with multisystem morbidities including cerebral edema, cardiac and skeletal muscle dysfunction from alteration of nerve impulses and membrane potentials.
- Mannitol is relatively iso-osmolal and is minimally metabolized (6 – 10%). This reduces the risk of fluid overload and hyponatraemia
HIGH VISCOSITY FLUIDS
The most commonly used high viscosity fluid is
- Dextran with high molecular weight (MW) 70,000 MW in a 10% water solution (Hyskon).
- Being highly viscous, small quantities are required for examination.
- Provides excellent visualization due to its high refractory index and as it does not mix with blood.
- Tends to “Caramelize” on instruments, which must be disassembled and thoroughly cleaned in warm water after each use. It may ‘freeze’ the stop cocks of the instruments, making them inoperable.
- Morbidities caused
- Pulmonary edema (non cardiogenic origin).
- Electrolytes imbalance.
- Anaphylactic reaction.
- Mechanical pump is necessary to deliver these fluids.
Useful Tips While using Distention Media
- To improve visualization,
- Overdilate the cervix to facilitate the overflow.
- Use of continuous flow sheath, promoting lavage of blood clots and debris.
- Direct aspiration with a disposable outflow catheter
- Uterine inflow depends upon
- Length, diameter and patency of inflow tubing.
- Viscosity of distention medium.Uterine outflow depends upon:
- Transtubal passage into the peritoneal cavity.
- Intravasation into the vascular tree.
- Leakage of the media through cervix.
- Continuous flow sheath interface.
- Intrauterine pressure depends on,
- Pressure of infusion device.
- Rate of inflow of media.
- Rate of outflow of media.Intrauterine pressure can be increased by
- Raising the height of media bag.
- Lowering the patients table.
- Lowering the patients table
- Closing the outflow part.
- By application of tenaculum on either side of an overdilated leaky cervix.
- Increasing pressure of infusion device.Intrauterine pressure can be decreased by
- Overdilating the cervix and making it leaky.
- Use of intermittent or constant suction to the outflow sheath.There is minimal drop in pressure due to transtubal passage and intravasation into the vascular tree.Sudden profound drop in intrauterine pressure should make one think of either obstruction of the inflow channels or uterine perforation.
D. Intravasation: Mean arterial pressure (MAP) is the intrinsic resistance of superficial layers to significant fluid absorption. Thus maintaining intrauterine pressures below MAP can prevent significant intravasation.
Since the pressure of the uterine veins is typically < 20 mm Hg, some absorption of fluid occurs inevitably. While surgical entry into the deeper intramyometrial veins abolishes the protective effects of the MAP, and can lead to unpredictable and dangerous intravasation.
The other contributory factors are the
- Length of surgery.
- Partial perforation
- False passage
- Cervical tears / injury.
- Surgery that leads to entry into myometrium opening larger vascular channels
- Myoma resection / division.
- Limit height of ditention media bag to 1 meter above the patient's table.
- Use of electronic machine, which can calibrate the flow rate and intrauterine pressures.
- Monitor Input / Output and calculate the deficit,If 500 to 1000 ml (less if the patient is medically compromised) is believed to be absorbed, the following should be undertaken:
- The procedure should be suspended until fluid status is ascertained,
- A Foley catheter should be placed, if not already in place;
- Consideration should be given to rapid conclusion of the operative procedure as appropriate, as once fluid absorption is started in and progress rapidly.
If greater than 1500 ml is absorbed or serum sodium is less than 125 mmol/L, the procedure should be terminated as rapidly as reasonable. Patients with a serum sodium level below120 mmol/L should be considered for treatment in a critical setting, especially if a hypotonic distending medium was used.
The best strategy to treat symptomatic hyponatremia is.
- Early detection and rapid initiation of treatment
- Early diuresis with Frusemide.
- Monitoring input / output and electrolytes.
- Restrict fluid intake.
- Supplement oxygen.
- Correct sodium levels (if sodium < 120 mmol/L critical care).
Thus the surgeon must be vigilant to recognize and quantify the volume deficit of distention media and act promptly.
- Mechanical Energy: These are in the form of 2 mm semirigid sharp as well as blunt scissors, biopsy forceps and the myoma screw. These instruments can be passed through the operating channel to obtain biopsy specimens, transecting base of small polyps, excising uterine septa and synechiae.
- Monopolar: This has been the traditional energy used for operative hysteroscopy. However one cannot use this energy in the office hysteroscopy as the fully conscious patient will not tolerate it and will complain of pain.
- Bipolar standard electrode.
- Bipolar versapoint: This bipolar cautery, marketed by Gynecare division has many advantages:
- It can be used with saline thus eliminating the side effects of using glycine
- The electrodes can easily pass through the operative channel of office hysteroscopy
- Instant vaporisation and dessication can eliminate resection chips
- Decrease in the amount of blood loss.
- The pain is minimal if you restrict the surgery to the endometrial level.
- Monopolar electrodes. This 2 mm electrode uses monopolar energy and has to be used in combination with nonionic media such as glycine.
- Bipolar electrode: This 2mm electrode uses bipolar energy and has to be used in combination with either non ionic media such as glycine or ionic media such as saline.
- Bipolar Versapoint electrodes: These 2 mm electrodes use bipolar energy and have to be used in combination with versapoint bipolar generator. These are of 3 type:
- Twizzle electrode
- Ball electrode
- Spring electrode.These are used in combination with ionic distention media such as saline.
- Unipolar resectoscope electrodes used in combination with working element. These are of 4 types: Loop, rollerball, cylinder and Calvins Knife. These have to be used in combination with monopolar cautery and glycine.
- Bipolar versapoint resectoscope electrodes used in combination with working element. There are two types: Loop and zero degree electrodes. These have to be used in combination with versapoint bipolar cautery and saline.
The advancement of Hysteroscopy, both diagnostic as well as operative, has significantly contributed to better management of Gynecological surgeries related to the uterus. Proper instrumentation is essential in achieving a complication free optimal outcome. The newer smaller diameter hysteroscopes coupled with advanced bipolar versapoint technology, usage of saline as a distention media, and outpatient minimal anaesthesia procedures has revolutionized present day Hysteroscopy.