Chapter 42 Diagnostic and Operative Hysteroscopy: Polypectomy, Myomectomy, and Endometrial Ablation

INTRODUCTION

Hysteroscopy is an accurate surgical approach for evaluating the uterine cavity and treating a multitude of abnormalities. At its essence, it involves the transcervical placement of a lens and light system into the uterine cavity while using gas or liquid for distension of the cavity. Modern hysteroscopy is performed almost exclusively with the addition of a camera and video monitoring system. Operative hysteroscopy is performed using an electrosurgical resectoscope or a sleeve with an operating channel to accommodate instruments for grasping, biopsying, or cutting with scissors or laser.

Today, in addition to being an excellent diagnostic technique, hysteroscopy has proven to be an effective and minimally invasive treatment for abnormal uterine bleeding, infertility, and early pregnancy loss. Some of the most common uterine pathologic conditions treated by hysteroscopy are polyps and myomas. Even in patients without intrauterine pathology, endometrial ablation, first performed hysteroscopically, has decreased the need for hysterectomy in patients with abnormal uterine bleeding unresponsive to medical therapy.

This chapter describes the standard methods for diagnostic and operative hysteroscopy and then offers details of the hysteroscopic treatment of polyps and fibroids, both submucous and pedunculated intracavitary lesions. The chapter also describes techniques for endometrial ablation, including traditional hysteroscopic ablation and several innovative methods.

HISTORY

Hysteroscopy, first described in the late 1800s, did not find widespread clinical use for more than 100 years. In 1869, Pantaleoni performed the first diagnostic and therapeutic hysteroscopy when he used a modified cystoscope to look into the uterine cavity and cauterize a hemorrhagic growth.¹ Early hysteroscopists used a tube to mechanically distend the uterus for visualization. Near the beginning of the 20th century, Dr. Isidor C. Rubin, a New York gynecologist best remembered for Rubin’s test, first used carbon dioxide (CO₂) to distend the uterus for hysteroscopy. Around the same time, Professor C. J. Gauss, a German surgeon and descendant of the famous mathematician, first performed hysteroscopy using fluid distension media.² However, hysteroscopy did not find widespread acceptance for another half-century.³

In the 1970s interest in hysteroscopy renewed, in parallel with the rapid advancement of diagnostic and operative laparoscopy. Probably the most important advances came in the form of improved methods for distending the uterine cavity, including use of viscous and low-density liquid solutions. Around the same time insufflation machines were designed for CO₂ and fluid media that utilized high pressure and low flow, rather than the low pressure and high flow used for laparoscopy.⁴^–⁶ Carbon dioxide was often used for diagnostic hysteroscopy, and fluid media became the standard for operative hysteroscopy. It was found that isotonic fluid was ideal for most operative procedures, whereas nonconductive hypotonic media was required for electrosurgical procedures.

The use of hysteroscopy became widespread in the 1980s with the development of better optics and lighting and the use of video cameras. Operative techniques for various intrauterine pathologic conditions continued to be developed. Most notably among these may be removal of submucous myomas using an enhanced urologic resectoscope,⁷ removal of uterine septum,⁸ and endometrial ablation using laser,⁹ resectoscopic loop,¹⁰ or rollerball.¹¹ Today, hysteroscopy has become a standard diagnostic and therapeutic technique performed by most gynecologists.

INDICATIONS

Diagnostic Hysteroscopy

The most common indications for evaluation of the uterine cavity are abnormal uterine bleeding and infertility. Although hysterosalpingography (HSG) and modern ultrasonography are relatively sensitive in detecting intrauterine anomalies, diagnostic hysteroscopy remains the most accurate method available to visualize the cervical canal and uterine cavity. Today, there remain two schools of thought regarding initial evaluation of the uterine cavity. Although many clinicians utilize HSG, transvaginal ultrasonography, and sonohysterography to diagnose intrauterine abnormalities, many gynecologists continue to utilize diagnostic hysteroscopy in the office setting for this purpose. In addition, most gynecologists combine hysteroscopy with every dilation and curettage (D&C) procedure to exclude previously undetected focal pathology and to verify that previously diagnosed polyps have been completely removed during the procedure.

Operative Hysteroscopy

The two most common indications for operative hysteroscopy are (1) directed biopsy of focal lesions and (2) treatment of intrauterine lesions, including endometrial polyps and intracavitary leiomyomas, uterine septa, and cornual tubal occlusion. Removal of uterine septum and treatment of cornual occlusion with cannulation are covered in Chapters 43 and 47.

Less common indications for operative hysteroscopy include retrieval of a “lost” intrauterine device with a retracted tailstring, discussed in Chapter 27. Hysteroscopy has also been used in early pregnancy for chorionic villus sampling. The newest indication is the placement of coils into the intramural section of the tube for permanent sterilization, which is covered in Chapter 28.

In the recent past, hysteroscopy was commonly used to perform endometrial ablation. Recently, automated ablation techniques that are not performed hysteroscopically have become more common.

BASIC HYSTEROSCOPIC EQUIPMENT AND TECHNIQUES

Types of Hysteroscopes

All hysteroscopes incorporate an optical system (including an eyepiece and objective lens) and a light source within a single barrel up to 4mm in diameter. The most commonly used rigid hysteroscope has an objective lens at the tip offset by 12 to 30 degrees from the horizontal plane, although a “0 degree hysteroscope” is also used and other lens angles are available.

Ridged Hysteroscope

A ridged hysteroscope is used with a sleeve, which allows for the input of distension media. A diagnostic sleeve has a diameter of up to 4.5mm and usually has only a media input channel. An operative sleeve has a diameter of 8 to 9mm and has three channels: an input and outflow channel for media and a 2-mm operating channel for the use of semirigid instruments. These include scissors, biopsy forceps, and graspers that can be used for a full range of hysteroscopic tasks. Laser fibers and coaxial bipolar electrodes have also been used through the operative channel.

A resectoscope, similar to a urologic resectoscope, has a 9-mm diameter sleeve with a built-in mechanism to extend and retract a monopolar electrosurgical device using a thumb lever. The monopolar device can be a 5- to 7-mm cutting loop for removal of polyps, septum, or leiomyoma, or a rollerball or barrel used for endometrial ablation.

Flexible Hysteroscope

A flexible hysteroscope resembles a short colonoscope with variable sizes ranging from 3.1 mm to 5.0 mm. The larger scope has an instrument port with a diameter of 1.8mm for the use of very delicate flexible instruments. The hysteroscope tip can be deflected up to 160 degrees using a thumb control near the eyepiece. It is often used in an office setting because of its small diameter (and thus no need for cervical dilation). In addition to diagnostic hysteroscopy, it can be used for fine procedures such as directed endometrial biopsy, chorionic villus sampling, tubal canalization, and removal of a “lost” intrauterine device.

Distension Media

The uterine cavity is a virtual space, which must be distended with either gas or fluid media to visualize the endometrium and intrauterine pathology in three dimensions. In the past, contact hysteroscopy was performed without distension media for diagnostic evaluation of the endometrium based on color, architectural pattern, and contour. Today, diagnostic and operative hysteroscopy are most commonly performed with fluid distension media.

Carbon Dioxide

Carbon dioxide was commonly employed for diagnostic hysteroscopy because it allows for excellent clarity in the absence of bleeding. Compared to fluid media, it allows a wider field of view at lower magnification and is not messy. However, when bleeding occurs it is difficult to clear the lens, resulting in limited visualization.

Carbon dioxide is less commonly used today than in the past for several reasons. A major cost disadvantage is that CO₂ requires the expense of a specially designed hysteroscopic insufflator that produces higher pressures (up to 100 mm Hg) at relatively low flow rates (40 to 60mL/min). This is in contrast to laparoscopic insufflators, which are designed to deliver relatively lower pressures (<25 mm Hg) at high flow rates (up to 6L/min).

Another problem associated with the use of CO₂ for hysteroscopy is the rare occurrence of fatal gas embolism. Although a small amount of CO₂ is rapidly absorbed and cleared from the body via respiration, an open vessel in the uterus can allow enough gas into the venous system to result in fatal heart block.¹² To minimize this risk when CO₂ is used for hysteroscopy, it has been recommended that the Trendelenburg position should be avoided, the cervix should not be dilated, and no operative procedures should be performed.

Dextran 70

One of the first fluid distension media used was high-viscosity dextran 70. A 32% solution of dextran 70 in 10% dextrose in water is a nonelectrolytic, nonconductive fluid with syrup-like consistency that can be used for both diagnostic and operative hysteroscopy. Because of its high viscosity, dextran 70 results in minimal leakage through the cervix and tubes. Because it is immiscible with blood, it allows for excellent visibility during surgical procedures. A syringe with manual pressure is most often used during hysteroscopy to slowly infuse dextran 70.

Dextran 70 is rarely used today as hysteroscopic distension media because of several associated problems.¹³ From an operational perspective, dextran 70 solutions cause instruments such as graspers and scissors to become permanently inoperable if the solution is allowed to dry on the instruments. This problem can usually be avoided by immediate cleaning shortly after finishing the procedure.

Fluid overload is one of the most common serious problems that can result from intravascular intravasation of dextran 70. Each 100mL of dextran 70 absorbed results in an increase in the intravascular volume of 800mL. For this reason, it is recommended to use no more than 500mL of the solution during an individual procedure.

Another risk of intravascular intravasation of dextran 70 is disseminated intravascular coagulopathy. The mechanism of this uncommon complication is suspected to be toxic effects of dextran 70 on pulmonary capillaries.

Finally, allergic reactions to dextran 70 have also been reported. The risk of anaphylaxis while using dextran 70 for hysteroscopy has been estimated to be as high as 1 per 1500 cases.¹⁴

Low-Viscosity Fluid

Low-viscosity fluids are the most common distension media used today because they are suitable for both diagnostic and operative hysteroscopy, are relatively inexpensive, and are relatively low risk. Isotonic electrolyte-containing fluids can be used for all operative procedures except those requiring traditional electrosurgery, although technologic advances have allowed its use even with these procedures. Hypotonic nonelectrolyte media is used for most electrosurgery (i.e., resectoscope) procedures.

Isotonic electrolyte-containing fluids are the most common distension media used for diagnostic hysteroscopy and operative procedures using mechanical instruments, laser, and more recently available bipolar energy. Two commonly used types are 0.9% sodium chloride and lactated Ringer’s solution.

Hypotonic nonelectrolyte-containing fluids are required when the unipolar resectoscope is used, and several types are available. The most common fluids used are 5% mannitol, 3% sorbitol, and 1.5% glycine. The theoretical advantage of 5% mannitol is that it is rapidly broken down by the liver into glycogen and is excreted through the kidney, with a half-life of 100 minutes.¹⁵

The advantage of low viscosity fluids over carbon dioxide and hyskon 70 is the ability to easily flush blood, mucus, bubbles, and tissue fragments out of the visual field and uterus. However, proponents of hyskon 70 point out that the miscibility of blood in low viscosity fluids can result in decreased visibility.

The major risk of all low-viscosity fluid media is potentially fatal fluid overload from intravascular absorption. Hypotonic nonelectrolyte media has the additional deadly risk of acute hyponatremia. Both fluids therefore require close monitoring of fluid used and fluid recovered at frequent intervals throughout the hysteroscopic case. Some institutions use a fluid management system (e.g., Dolphin II, CIRCON, British Columbia, Canada) for this purpose.

When a fluid deficit of 1,000mL of nonelectrolyte solution is identified, blood should be drawn to determine electrolyte levels, the procedure should be terminated, and consideration should be given to administering diuretics, with close monitoring of electrolytes. Injection of 3 to 4mL of dilute vasopressin (10 units in 50mL saline solution) into the cervix decreases both intraoperative bleeding and intravasation for at least 20 to 30 minutes.¹⁶

Analgesia and Anesthesia

Narrow rigid and flexible hysteroscopes with diameters less than 4mm can often be inserted into the uterus without dilating the cervix. For this reason, they are often used in an office setting using only oral analgesics or with the addition of a paracervical block.

For operative procedures, larger hysteroscopes and resectoscopes are used that require cervical dilation before insertion and are therefore used primarily in an operating room under general or regional anesthesia.

Power Sources

The first, and perhaps most versatile, hysteroscopic power source is unipolar electrosurgery. A resectoscope with a thin loop electrode is used to resect leiomyomas or divide a septum. This approach is ideal for resecting dense tissue and maintaining hemostasis. Because this is a monopolar device, it must be used with nonconducting hypotonic distension media. Bipolar and insulated monopolar systems have been developed, with the advantage of working with the safer isotonic distension media. These methods are more expensive because they are based on disposable technology.

Several lasers have been developed for endometrial ablation, including the potassium-titanyl-phosphate (KTP), argon, and neodymium:yttrium-aluminum-garnet (Nd:YAG) lasers. Each has relative advantages and disadvantages and tends to be more technically challenging and expensive than electrosurgerical techniques.

DIAGNOSTIC HYSTEROSCOPY

For the majority of the 20th century, the only method available for directly visualizing intrauterine pathology short of hysterectomy was the blind procedure of D&C. In the 1970s, dramatic improvements in optical systems, light sources, and distension media allowed the widespread use of hysteroscopy for accurate diagnosis (and often treatment) of intrauterine pathology.

In the 1980s, the development of hysteroscopes with smaller diameters (<4mm) allowed the use of the hysteroscope for diagnosis without the need for either cervical dilation or anaesthesia. As a result, office hysteroscopy has become a common procedure, which has been documented to have the advantages of patient acceptability, diagnostic accuracy, and cost- effectiveness.¹⁷ Hysteroscopy is particularly useful for identifying focal lesions, which are often missed with endometrial sampling.¹⁸

Office Hysteroscopy

Office hysteroscopy is comfortable, quick, and associated with low complication rates. The cervix can be made more pliable by the use of oral or vaginal misoprostol to make the procedure more tolerable, especially in women at risk for cervical stenosis. Oral analgesics, such as ibuprofen, are also helpful.

A low (<1%) complication rate is noted when office hysteroscopy is performed by skilled physicians. Complications include uterine perforation, infections, excessive bleeding, and complications related to the distension media.¹⁹

Common Pathology

The list of lesions that can be visualized hysteroscopically is long and includes endometrial polyps, submucosal and intramural myomas, synechiae, retained products of conception, foreign bodies, endocervical lesions, endometrial atrophy, endometrial hyperplasia, endometrial cancer, arteriovenous malformations, gestational trophoblastic disease, cesarean scar defects, incomplete abortion, and pregnancy. In some cases, endometrial gland openings associated with adenomyosis can be observed. Theoretically, the specificity and positive predictive value of hysteroscopy in cases of abnormal uterine bleeding should be 100%. In practice, however, the false-negative rate is 2% to 4% and is the result of operator error in detecting abnormal endometrial lesions.

Technique

A slow and thorough evaluation is important to identify abnormalities of the endocervix, fundus, and tubal ostia. Myomas of the endocervix and lower uterine segment can easily be missed with too rapid insertion of the hysteroscope. Likewise, if the hysteroscope is too quickly placed above an intracavitary lesion, it can likewise be missed.

Lesion Size

The size of lesions cannot be accurately determined hysteroscopically, in contrast to transvaginal ultrasound. This is because the hysteroscopic eyepiece is focused at infinity, thereby making the objects that are closer appear magnified and objects viewed further away smaller.²⁰ This phenomenon can lead to surprises in the operating room, especially when the size of a lesion, particularly submucosal myomas, may be underestimated.

Disappearing Phenomena

False-negative views can occur during hysteroscopy when using CO₂ because of the high intrauterine pressures. The disappearing phenomena refers to the flattening of endometrial polyps, resulting in a negative hysteroscopic view. This can be avoided by decreasing the intrauterine pressure at the end of the procedure and reinspecting the endometrial cavity.

HYSTEROSCOPIC POLYPECTOMY

Endometrial polyps are benign growths found within the uterine cavity. They are often asymptomatic and can perhaps remain undetected for decades. In women without symptoms, polyps are often found coincidentally when pelvic ultrasonography is performed for unrelated problems such as pain or during the investigation for infertility.

Polyps are often symptomatic. However, in women with abnormal uterine bleeding, investigation may lead to their detection. Symptoms most often related to uterine polyps include abnormal bleeding, postcoital staining, chronic vaginal discharge, or dysmenorrhea. Polyp-related bleeding is often characterized by increased clotting, intermenstrual or premenstrual spotting, or heavier menstrual flow. There is good evidence that polyps can decrease fertility and that their removal will improve the chances of pregnancy.²¹

In addition to women with abnormal bleeding and infertility, other women at increased risk for endometrial polyps include women on tamoxifen therapy and women with endocervical polyps, a quarter of whom will also have endometrial polyps.

It is obvious that symptomatic endometrial polyps should be removed. However, it is also important to remove asymptomatic polyps, particularly in postmenopausal women.²² Although the vast majority are benign, endometrial cancer and hyperplasia will be found in approximately 2% of endometrial polyps and are associated with coexisting malignancies elsewhere in the endometrium. In one study of more than 1400 polyps, endometrial cancer was found in 27 polyps (1.8%).²² All but one of these women were postmenopausal, and 26% were asymptomatic.

HYSTEROSCOPIC MYOMECTOMY

Leiomyomas are the primary indication for more than 40% of the 650,000 hysterectomies performed annually in the United States.²³ Submucosal myomas likely account for 10% to 20% of all myomas. Many of these can be removed by operative hysteroscopy. In addition to preserving fertility in many cases, a hysteroscopic approach is associated with a shorter recovery period, lower complication rate, and lower cost than hysterectomy.

For a successful surgical outcome, it is important to identify preoperatively the size, number, location, and depth of intramural extension of uterine myoma. Myoma size, number, and location are determinants of complete resectability, the number of surgical procedures necessary for complete resection, the duration of surgery, and the potential complications from fluid overload.²⁴

Numerous studies have demonstrated that preoperative saline infusion sonohysterography gives more information than hysteroscopy in respect of myomas. Chapter 30 reviews the topic of ultrasonography and sonohysterography in detail.

Hysteroscopic Classification of Myomas

A classification system is important to most accurately determine the appropriate method for performing myomectomy and counseling the patient on risk and prognosis. The European Society of Hysteroscopy classification system is based on myoma location and the amount of myoma protruding or encroaching on the endometrial cavity.²⁵ In this system, Type 0 myomas are pedunculated, with the myoma lying completely within the endometrial cavity (Fig. 42-1). Type I myomas are described as sessile, with less than 50% intramural extension (Fig. 42-2). Finally, Type II myomas are submucosal in location, with more than 50% intramural extension. These include transmural myomas, which extend from the submucosal to the serosal edge. When viewed hysteroscopically, Type II myomas appear as a “bulge” into the endometrial cavity. Multiple myomas such as those in Figure 42-3 are not placed within this classification. They should not accessed by hysteroscopy.

Figure 42-1 Hysteroscopic view of a type 0 myoma. It is pedunculated and the total myoma lies within 100% of the endometrial cavity.

Figure 42-2 Hysteroscopic view of a type I myoma that involves less than 50% of the myometrium.

Figure 42-3 Extirpated uterus showing a large (6 cm) intracavitary myoma with multiple intramural and submucous myomas.

This system was originally designed to classify myomas exclusively on hysteroscopic appearance. However, this approach has significant limitations. During hysteroscopy, myomas can be compressed and recede into the myometrium as a result of the pressure of the distension media, thereby preventing full visualization of the myoma. For this reason, preoperative evaluation with ultrasonography is required to accurately determine how many myomas are present and how deeply the myomas penetrate the myometrium.

An ultrasonographic classification system has been developed for intramural myomas that corresponds in part to the hysteroscopic classification and in part to the hysterosalpingography data ²⁶ (Table 42-1).

• Class 1 myomas are intracavitary and do not involve the myometrium. The base or stalk is visible on saline infusion sonohysterography (Fig. 42-4).

• Class 2 myomas have a submucosal component that involves less than 50% of the myometrium (Fig. 42-5).

• Class 3 myomas have an intramural component greater than 50%. They can be transmural and located anywhere from the submucosal to the serosa. These myomas often appear as a bulge or indentation into the submucosal when viewed hysteroscopically (Fig. 42-6).

Table 42-1 Hysteroscopic and Sonohysterographic Classification System for Myomas Encroaching Upon the Endometrial Cavity

Hysteroscopic Type²⁵	Sonohysterographic Class²⁶	Description
Type 0	Class 1	Pedunculated myomas, where 100% of the myoma lies within the endometrial cavity with no intramural extension
Type I	Class 2	Sessile myomas, with <50% intramural extension
Type II	Class 3	Submucous myomas, with >50% intramural extension