Principles of Hysteroscopic Surgery

Principles of Hysteroscopic Surgery

Key Points

  • Preparation for any surgical procedure, including hysteroscopic surgery, is a strategy that comprises a synthesis of education, communication and a medical process. 
  • Informed consent is more than a signed document; it is an iterative process that combines questioning, counseling and balancing the risk of an intervention with the anticipated benefit in a way that allows the patient to formulate an informed decision. 
  • The risks associated with hysteroscopy are real but are minimized if the procedures are performed by individuals with appropriate training who are practicing in an environment with adequate staff, supplies and equipment.
  • Regardless, it is important that patients are provided information regarding the risks of hysteroscopic surgery that allow them to make the informed decision.
  • There exist a number of medical interventions that may improve the outcome of a hysteroscopic surgical procedure that include suppression of endogenous estrogenic activity to thin the endometrium, ripening of the cervix to reduce the force of dilation and preemptive analgesia to reduce procedure pain if the hysteroscopic intervention is performed under local anesthesia.

 

Introduction

Hysteroscopic surgery refers to the endoscopically directed performance of intrauterine procedures including myomectomy, endometrial ablation, adhesiolysis, polypectomy, IUD removal, transection of a uterine septum, and evacuation of retained products of conception. Properly perfomed by appropriately trained surgeons, hysteroscopic surgery is safe and effective and can frequently be performed in an office procedure room using minimal or local anesthesia.

Patient Evaluation

Principles of Patient Evaluation

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Regardless of the clinical problem - infertility, recurrent pregnancy loss, postmenopausal bleeding or abnormal uterine bleeding (AUB) in the reproductive years - it is critically important that the patient be evaluated in a structured fashion before undertaking any procedural intervention for diagnosis and especially for therapy. There are a number of findings such as polyps and leiomyomas that may or may not be responsible for the symptom(s) presented by the patient, and other nonstructural entities such as ovulatory disorders or coagulopathies that may have a more important role. Consequently, a carefully performed menstrual history as suggested by FIGO System 1 (Munro et al 2018), and appropriately performed uterine evaluation, are mandatory components of the assessment process. We will not belabor many of them here, but will focus on uterine evaluation. This is the key to appropriate patient selection for hysteroscopic procedures, not only for efficacy, but for safety.

Uterine Evaluation

The main congenital structural anomalies of the uterus include the spectrum of Müllerian anomalies, while the "acquired" structural abnormalities include polyps, adenomyosis, leiomyomas, and malignancy, the "PALM" group of FIGO's System 2 also known as the "PALM-COEIN" system. Hysteroscopic surgery is particularly appropriate for polyps, most submucous leiomyomas (Types 0, 1, 2 and sometimes 3), and for transection of rASRM Class 5 septums (or CONUTA U2 a & b). However, not all leiomyomas are amenable to hysteroscopic resection and transection of septums must be performed only after confirming that indeed it is an ASRM Class 5/CONUTA U2 anomaly. When evaluating the suitability of Type 2 or 3 leiomyomas for hysteroscopic removal, it is important to be certain that the "myoma-free" or "outer-free" margin of myometrium, between the myoma and the serosa is adequate; in other words, that these are not Type 2-5 or 3-5 tumors. This process requires a diligent, conscientious, and structured approach using a spectrum of imaging techniques. This process is described here.

Equipment and Supplies

Hysteroscope and Sheaths

Like other endoscopes, traditional hysteroscopes comprise an eyepiece, a distally located lens and an intervening shaft that is typically about 30 cm in length. The design includes a mechanism for transmitting the image from the distal lens to the eyepiece and fiberoptic bundles that transmit light, usually from an external source, to the distal end of the endoscope for illumination of the uterine cavity (cervical canal + endometrial cavity). The transportation of distending media to and from the endometrial cavity usually requires that the hysteroscope be inserted into one or more outer sheath, or sheathes designed for that purpose .


One way of categorizing hysteroscopes is into flexible and rigid designs. Flexible hysteroscopes are similar to those used by gastroenterologists and are self-contained, typically don't require a sheath for instillation and removal of distending media and are generally of smaller diameter than rigid systems. Both light and image are transmitted by separate bundles of optical fibers. The channel used to transmit distension media usually doubles as a portal for the insertion of operating instruments. Typical flexible hysteroscopes are “steerable” with a deflectable tip that angle the view so that lateral aspects of the endometrial cavity, including the corneal areas can be seen. The operative channel of steerable flexible hysteroscopes is generally the only port and is usually too small for most operative instruments, so they are primarily used for diagnostic imaging. 

Whereas the viewing angle of flexible hysteroscopes can be varied or “steered”, that of rigid hysteroscopes is fixed. However, by varying the angle of the distal lens of a rigid hysteroscope, a ‘foreoblique” view can be obtained. Furthermore, the cavity can be scanned by rotation the hysteroscope on its long axis. Consequently, rigid hysteroscopes are available in a 0-degree format as well as a range of foreoblique angles in two size ranges - between 12 and 15 degrees as well as from 25 to 30-degrees (see figures A and B). The angle of the distal lens of the hysteroscope is, by convention, directed away from the location of the proximally-located light post used to attach the endoscope to the light cable. This relationship helps orient the surgeon to the direction of view for foreoblique systems.


The choice of viewing angle is, in part, a matter of personal preference, but in part a matter of necessity. The 0-degree endoscopes provide easy orientation to the image, since it is similar to that of normal vision and they are easy to orient for insertion through the cervix into the endometrial cavity (A). However, the flat terminal end of the 0 degree hysteroscope neither lends itself to atraumatic passage through the curvilinear cervical canal nor does it allow for any angled viewing within the endometrial cavity. Visualized entry into the endometrial cavity through the cervical canal is impacted by the viewing angle. The axis of the cervix is aligned with the viewing angle for a 0º hysteroscope, but the differences posed by oblique lenses require that the surgeon adjust the insertion angle to account for this phenomenon (See A and B).


The rod lens-based construction of a rigid hysteroscope provides both a more durable instrument and a superior image. Commonly used rigid hysteroscopes vary from 2 to 4 mm in outside diameter (OD). To function most effectively channels are needed to deliver and remove media and instrumentation. Although there are some specially designed systems, most require an outer cylindrical tube or “sheath” or sheathes as they include the conduits necessary for delivery of distention media and operative instruments into the endometrial cavity. The sheath may have only a single channel for instillation of distension media but at least two media channels are preferred because continuous inflow and outflow of fluid distension media is associated with improved visualization of the operative field secondary to clearance of blood and tissue debris. Such continuous flow systems are essential for any complex operative hysteroscopic procedure.  In addition, operative sheaths and systems include additional channels to allow for insertion of a range of integrated or accessory instrumentation These features add to the overall OD of the system placed through the cervical canal; ranging from about three to five mm for simple diagnostic systems, to between five and nine mm for electromechanical and RF resectoscopic systems. 

Distending Media and Management

Key Points


  • Distention media are needed for hysteroscopy for the purpose of converting the potential space of the endometrial cavity to a real space 
  • Options for uterine distention include CO2 and fluid media. CO2 is not suitable for operative procedures
  • Hypotonic, non electrolytic fluids solutions containing glycine, sorbitol and mannitol are required for the use of RF electrosurgery with monopolar instrumentation
  • Excessive absorption of hypotonic fluids can result in fluid overload and hypotonic hyponatremia, causing permanent neurological complications or death.
  • Normal saline is a safer media because, even with moderate levels of absorption, electrolyte levels are normal
  • Bipolar RF instrumentation require saline media, a circumstance that makes them safer than monopolar instrumentation when excess media is absorbed into the systemic circulation. 
  • Distention media management systems that control infusion pressure and monitor systemic absorption are recommended when it is known or suspected that the integrity of the myometrium will be breached during the procedure. 
  • The maximum allowable absorption of electrolyte free media ranges from 500 mL to a maximum of 1,000 mL
  • The maximum allowable absorption of normal saline ranges from 1,500 to 2,500 mL depending in large part on their baseline cardiopulmonary function
  • Hysteroscopic programs should have protocols that guide the termination of procedures when the preset thresholds are met

Systems for Media Management

Hysteroscopy depends on the conversion of a potential space (the endometrial cavity) into an actual space for viewing and targeting pathology. The media used may be gaseous CO2  or low viscosity liquids. Carbon dioxide gas requires gas tanks, a special insufflator, often referred to as a ‘Hysteroflator®’ and is unsuitable for operative hysteroscopy.. The low viscosity fluids either contain electrolytes, such as normal saline or are electrolyte free, the latter including dextrose in water and those with a sugar molecule to increase osmolality such as 3% glycine, 1.5% sorbitol and 5% mannitol. 


There are essentially three components of fluid management. These comprise infusion of the media into the endometrial cavity, removal from the endometrial cavity and either estimation or quantification of the amount of fluid that might be absorbed into the systemic circulation, either through breaches in endomyometrial blood vessels or by extravasation through the fallopian tubes. 


The most simple system for distention is a syringe filled with fluid media attached to the hysteroscopic system directly or with tubing. Such an approach may be very useful and appropriate for simple diagnosis but is not particularly practical for operative procedures. The most commonly used “simple” system exploits gravity by suspending a bag of distention media from the a pole designed for intravenous solutions (“IV Pole”). The pressure generated can be changed by varying the diameter of the tubing or the height of the media above the uterus. Pressure can be augmented with an inflatable cuff placed around the bag. More sophisticated systems generate pressure using and infusion pumps that are pressure-sensitive pumps and maintain a preset intrauterine pressure. 


Simple diagnostic systems have no dedicated outflow port. Media are removed from the endometrial cavity drainage after disconnecting the infusion tubing, or by completely removing the hysteroscopic system. For systems with a dedicated outflow port, called continuous flow systems, tubing can be connected and directed either passively into a receptacle or bucket, or, attached to low-pressure suction. 


The passage of significant volumes of distending media into the systemic circulation can pose a hazard to electrolyte balance, with electrolyte free media and to cardiac overload with any type of media (Arieff et al 1987, Ayus et al 1992, Istre et al 1994). Consequently, a number of fluid management systems are available to continuously monitor inflow and outflow of distension fluid and provide “real-time” monitoring of fluid balance. Most systems measure the discrepancy by the weight of infused versus collected fluid, or, alternatively, the volume of the infused fluid compared to the weight of the outflow fluid. This requires that the system be calibrated prior to the procedure. Most systems provide a user adjustable alarm that sounds when a preset discrepancy has occurred. Many operating rooms require the use of a fluid management system to enhance patient safety.

Anesthesia

Key Points

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  • While many women, particularly those who require diagnostic hysteroscopy only, require no analgesia, many require uterine anesthesia be it using local, regional or general anesthetic techniques.
  • Anxiety contributes to the perception of pain, so when performing hysteroscopic procedures in an office or clinic environment, efforts should be made to reduce anxiety based on the appearance of the room, its temperature and the general mood which can be affected by noise or other interruptions and the comportment of the medical and support staff.
  • Women should be reassured that if the procedure causes undue pain, it will be terminated and plans made to complete it at a later time and possibly under different conditions such as with different anesthesia and possibly in an alternate location.
  • There is evidence that music reduces both anxiety and pain.
  • There is high quality evidence that, at least for diagnostic hysteroscopy, the vaginoscopic technique is feasible and comfortable for the vast majority of women.
  • Local anesthetic techniques, appropriately applied, can allow the performance of the entire spectrum of hysteroscopic surgical procedures. There is increasing evidence that the vagina and the entire uterus should be considered and approach that recognizes the unique and variable innervation of the uterus.
  • Regardless of the analgesia or anesthetic technique used women should be encouraged to have a support individual available to accompany them home following the procedure. This is mandatory should psychoactive or systemic anesthetic agents be used for the procedure.


Access to the Endometrial Cavity

Key Points

  • Without successful access to the endometrial cavity, hysteroscopy is not possible, so careful attention to technique is critical to success. 
  • There exist a number of techniques whereby uterine access can be achieved and not all are applicable to all patients. Consequently, the effective hysteroscopist should be facile at more than one approach.
  • Visual entry using the hysteroscope is the preferred approach; blind entry techniques are to be discouraged
  • In some instances access is difficult, a circumstance that may necessitate the use of a number of ancillary techniques including concomitant transabdominal ultrasound. 



Vaginoscopic Technique

The vaginoscopic approach for accessing the endometrial cavity does not require the use a speculum or tenaculum and reduces discomfort at least with simple diagnostic procedures (Cooper et al 2010). The distal end of the assembled hysteroscopic system is passed into the lower vagina while the liquid distension media is infused. The pool of fluid in the upper vagina allows visualization of the exocervix and external os. The hysteroscope is gently advanced through the visualized external os into cervical canal and through to the the endometrial cavity. Vaginal distention can be facilitated by opposing the vulva with the gloved fingers of the free hand to minimize egress of fluid from the vagina. When anatomy or other clinical features makes such distention difficult, an inflatable laparoscopic vaginal pneumo-occluder, positioned and slightly inflated around the hysteroscopic sheath can facilitate this process. 

Speculum/tenaculum Technique

The traditional approach is used when the vaginoscopic technique is neither feasible nor successful. The clinician should select the smallest speculum compatible with adequate exocervical exposure. A bivalve speculum hinged on only one side (“open-sided”) can be removed without disturbing the position of the tenaculum and hysteroscopic system. The use of weighted specula should be avoided when using local anesthesia because of patient discomfort. F


The hysteroscope should be the first instrument to enter the cervical canal and the endometrial cavity. Such a visual entry technique should reduce the risk of perforation and allows visual assessment of the cervical canal and endometrial cavity unaffected by trauma from sounds and dilators.


When cervical dilation is necessary the process should be undertaken carefully, respecting the version (orientation of the cervical access to that of the vaginal canal (version) and flexion, that of the corpus to the cervix . A tenaculum, attached to the anterior cervix, and held with subsequent gentle traction helps to reduce the degree of version and provides a degree of counterforce to facilitate passage of the hysteroscopic assembly through the cervical canal into the endometrial cavity. 


Visualization of the Uterine Cavity

The endometrial cavity is the distal component of the uterine cavity  and is connected to the vagina by the cervical canal. Since the endometrial cavity is only a potential space, visualization requires that dissension media be instilled with pressure that is adequate to provide visualization.

Intrauterine Electrosurgery

Key Points


  • Radiofrequency (RF) electrosurgery is an important tool for the hysteroscopic surgeon as it can be used to transect or resect (morcellate) tissue, or to obtain hemostasis.
  • Electrosurgery is the application of RF alternating current to tissue resulting in elevation of intracellular temperature adequate to result in tissue vaporization or coagulation
  • All electrical circuits are  "bipolar" in that they requires the existence of two electrodes with opposite polarization. The most common electrical circuit is the so-called "Direct Current" or DC circuit, where polarity is maintained, a circumstance typified by a common battery.
  • Alternating polarity circuits (alternating current  or AC) change the polarity of the two electrodes with each half cycle
  • RF electricity is a version of alternating polarity where the frequency of the change in polarity is about 400,000 to 500,000 times per second, or 400 to 500 kiloHertz, a similar frequency to AM radio from which the term "radiofrequency" gets its name.
  • The rapid switching of polarity means that there is no flow of electrons around a circuit - instead the electrons oscillate at this rapid rate, an example of the conversion of electromagnetic energy to kinetic energy
  • This rapid oscillation of ions within the cell results in the conversion of kinetic energy to thermal energy, which is responsible for the increase in intracellular temperature
  • Rapid focused elevation of temperature results in cellular vaporization, which can be extended in a linear fashion to cut tissue.
  • Less rapid, less focused elevation of intracellular temperature results in both cellular desiccation and protein coagulation - the basis behind the "sealing" effect of RF electrosurgery.
  • Learning to control these two effects effectively and safely is the responsibility of the hysteroscopic surgeon.

Hysteroscopic RF instrumentation is either monopolar or bipolar

Intrauterine Dissection

Tissue Removal

Adverse Events: Prevention, Recognition, and Management

References

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