Introduction

With the introduction of minimal-access surgical techniques like hysteroscopy, the ability was created to remove intrauterine disorders selectively with great patient satisfaction and important advantages to both the patient and the surgeon. In such cases, a hysterectomy can be prevented, and this is of extreme importance especially for women who wish to retain their fertility.

Patients consult the gynaecologist for complaints of heavy menstrual bleeding. Approximately one-third of these patients have an intrauterine disorder (submucous myoma or endometrial polyp) . After diagnosing such an intrauterine disorder by ultrasonography or hysteroscopy, surgical removal is often scheduled.

Hysteroscopy is the process of viewing and operating in the endometrial cavity from a transcervical approach. The basic instrument is a long, narrow telescope connected to a light source to illuminate the area to be visualised. With a patient in the lithotomy position, the cervix is visualised and the distal end of the telescope is passed into a cervical canal, and, under direct visualisation, the instrument is advanced into the uterine cavity. A camera is attached to the proximal end of the hysteroscope to broadcast the image onto a video monitor. Given their safety and efficacy, diagnostic and operative hysteroscopy have become standards in gynaecological practice. Over the past few decades, refinements in optic and fiberoptic technology and inventions of new surgical accessories have dramatically improved visual resolution and surgical techniques in hysteroscopy . Many hysteroscopic procedures have replaced old and/or invasive techniques like dilatation and curettage and hysterectomy.

Fibroids or (leio)myomas are benign tumours that very commonly derive from smooth muscle cells of the myometrium. They are the most common indication for a hysterectomy. However, in women desirous of preservation of their uterus or of their fertility, a myomectomy may be a more appropriate form of surgical therapy. In 1976, Neuwirth and Amin reported five cases of excision of the submucous variant with a hysteroscopic control. The above-mentioned refinements of hysteroscopic surgical technique have resulted in a better ability to remove submucous myomas with the preservation of the uterus. The state of the art of such hysteroscopical techniques and instrumentation to treat submucous myomas is discussed.

Diagnosis and preoperative evaluation

To address the absence of consensus about the nomenclature of causes for abnormal uterine bleeding, the Fédération Internationale de Gynécologie et d’Obstétrique (FIGO) has designed the PALM-COEIN (polyp, adenomyosis, leiomyoma, malignancy and hyperplasia, coagulopathy, ovulatory disorders, endometrial disorders, Iatrogenic causes and not classified) classification system . This classification system categorises the submucosal variant of fibroids according to our publication of 1993 : intracavitary myomas that are attached to the endometrium by a narrow stalk are classified as type 0; types 1 and 2 myomas require that a portion of the lesion is intramural, but with type 1 being ≤50% and type 2 >50%. The type 3 myomas are completely extracavitary but abut the endometrium. Type 4 lesions are intramural myomas that are entirely within the myometrium, with no extension to the endometrial surface.

During the last decade, transvaginal ultrasonography of the uterus has become a routine procedure in the diagnostic workup of several gynaecological problems. It has been demonstrated that a normal sonographic finding is very accurate for the exclusion of clinically significant intracavitary abnormalities . Furthermore, this normal sonographic finding is very well reproduced in the hands of different examiners . However, in the case of abnormal or inconclusive sonographic findings, diagnostic accuracy and reproducibility decline. To improve the image in these cases, sonographic examination using artificial uterine cavity distension was first described at our department . Saline infusion sonohysterography (SIS) is extensively described in the literature . It is accepted that SIS improves the diagnostic accuracy of transvaginal ultrasonography in case of abnormal or inconclusive findings, and that SIS is an effective early diagnostic step in the evaluation of patients with premenopausal and postmenopausal abnormal uterine bleeding. The only contraindications are pregnancy and pelvic infection. Although the visualisation of the uterine cavity and its linings improves significantly, patients experience inconveniences and discomfort due to either fluid leakage whilst using a catheter without a balloon or pain with the use of a balloon catheter. In trying to overcome these disadvantages and to create a more stable filling of the uterine cavity, we modified the technique of SIS by instilling gel instead of flushing or infusing saline. This new technique and first experiences of gel instillation sonohysterography (GIS) were described . Three-dimensional (3D) and four-dimensional ultrasound images can be achieved with a stable and adequate distension of the uterine cavity. This can only be achieved by the use of a gel. We have adopted the term virtual hysteroscopy for such type of imaging. Further improvement of ultrasound technology and computer processing will create images revealing diagnostic information that is equally accurate as diagnostic hysteroscopy with comparable or less pain and/or inconvenience for the patient.

For an adequate preoperative evaluation of a submucous myoma, it has been proven that a concomitant 3D contrast ultrasonographical examination has low interobserver and intraobserver variability with a good reproducibility of measuring the protrusion of the fibroid into the cavity . Apart from properly classifying the intramural extension of the myoma, particularly the evaluation of the thickness of the myometrium between the intramural portion of the myoma and the serosa is important to prevent perforation during a hysteroscopic treatment. There are no generally accepted limits of this thickness although a minimal of 5 mm is often mentioned. Further, the surgeon should always be aware of this thickness, and extreme caution should be employed while addressing the deepest intramurally located part of the fibroid.

Apart from that, the precise measurement of the size, or better the volume, of the fibroid is often somewhat disregarded, while this is of paramount importance. In most cases, fibroids with a deeper intramural extension have a larger volume. During their growth, it takes longer for a type 2 fibroid to reach the uterine cavity and to start being symptomatic than it takes for a type 0 fibroid; the last variant tends to be smaller.

Diagnosis and preoperative evaluation

To address the absence of consensus about the nomenclature of causes for abnormal uterine bleeding, the Fédération Internationale de Gynécologie et d’Obstétrique (FIGO) has designed the PALM-COEIN (polyp, adenomyosis, leiomyoma, malignancy and hyperplasia, coagulopathy, ovulatory disorders, endometrial disorders, Iatrogenic causes and not classified) classification system . This classification system categorises the submucosal variant of fibroids according to our publication of 1993 : intracavitary myomas that are attached to the endometrium by a narrow stalk are classified as type 0; types 1 and 2 myomas require that a portion of the lesion is intramural, but with type 1 being ≤50% and type 2 >50%. The type 3 myomas are completely extracavitary but abut the endometrium. Type 4 lesions are intramural myomas that are entirely within the myometrium, with no extension to the endometrial surface.

During the last decade, transvaginal ultrasonography of the uterus has become a routine procedure in the diagnostic workup of several gynaecological problems. It has been demonstrated that a normal sonographic finding is very accurate for the exclusion of clinically significant intracavitary abnormalities . Furthermore, this normal sonographic finding is very well reproduced in the hands of different examiners . However, in the case of abnormal or inconclusive sonographic findings, diagnostic accuracy and reproducibility decline. To improve the image in these cases, sonographic examination using artificial uterine cavity distension was first described at our department . Saline infusion sonohysterography (SIS) is extensively described in the literature . It is accepted that SIS improves the diagnostic accuracy of transvaginal ultrasonography in case of abnormal or inconclusive findings, and that SIS is an effective early diagnostic step in the evaluation of patients with premenopausal and postmenopausal abnormal uterine bleeding. The only contraindications are pregnancy and pelvic infection. Although the visualisation of the uterine cavity and its linings improves significantly, patients experience inconveniences and discomfort due to either fluid leakage whilst using a catheter without a balloon or pain with the use of a balloon catheter. In trying to overcome these disadvantages and to create a more stable filling of the uterine cavity, we modified the technique of SIS by instilling gel instead of flushing or infusing saline. This new technique and first experiences of gel instillation sonohysterography (GIS) were described . Three-dimensional (3D) and four-dimensional ultrasound images can be achieved with a stable and adequate distension of the uterine cavity. This can only be achieved by the use of a gel. We have adopted the term virtual hysteroscopy for such type of imaging. Further improvement of ultrasound technology and computer processing will create images revealing diagnostic information that is equally accurate as diagnostic hysteroscopy with comparable or less pain and/or inconvenience for the patient.

For an adequate preoperative evaluation of a submucous myoma, it has been proven that a concomitant 3D contrast ultrasonographical examination has low interobserver and intraobserver variability with a good reproducibility of measuring the protrusion of the fibroid into the cavity . Apart from properly classifying the intramural extension of the myoma, particularly the evaluation of the thickness of the myometrium between the intramural portion of the myoma and the serosa is important to prevent perforation during a hysteroscopic treatment. There are no generally accepted limits of this thickness although a minimal of 5 mm is often mentioned. Further, the surgeon should always be aware of this thickness, and extreme caution should be employed while addressing the deepest intramurally located part of the fibroid.

Apart from that, the precise measurement of the size, or better the volume, of the fibroid is often somewhat disregarded, while this is of paramount importance. In most cases, fibroids with a deeper intramural extension have a larger volume. During their growth, it takes longer for a type 2 fibroid to reach the uterine cavity and to start being symptomatic than it takes for a type 0 fibroid; the last variant tends to be smaller.

Preoperative preparation

Studies examining the use of pharmaceutical (prostaglandins and antiprogestogens) and mechanical (osmotic dilators) dilatation of the cervix before hysteroscopic surgery have produced conflicting results regarding their effect on cervical dilatation and trauma during the procedure. A meta-analysis of six randomised controlled trials (RCTs) that examined women undergoing hysteroscopy where the intervention was the use of cervical preparation versus a control or a placebo revealed that there is no evidence to recommend the routine administration of mifepristone or misoprostol to women before hysteroscopy . Cervical priming with vaginal prostaglandins may be considered in postmenopausal women if using hysteroscopic systems of a larger diameter.

Although a thin endometrium improves visualisation of the borders of a myoma during hysteroscopic procedures, endometrial preparation was never the subject of an RCT related to hysteroscopic myomectomy. The same counts for the use of a medication that is known to reduce the size of the myoma. One would expect that a preoperative use could result in more complete removals; however, this was never proven for gonadotrophin-releasing hormone analogues (GnRHa). The use of GnRHa for 3–4 months prior to fibroid surgery reduces both uterine volume and fibroid size. They are beneficial in the correction of a preoperative iron deficiency anaemia, if present . The preoperative use of ulipristal acetate, a selective progesterone receptor modulator (SPRM), showed similar results ; amenorrhoea and fibroid size reduction, but advantages during hysteroscopic surgery were never studied. In a meta-analysis of 11 RCTs involving 780 women with symptomatic uterine fibroids, it was demonstrated that mifepristone (another SPRM) could also effectively reduce uterine and fibroid volume and alleviate symptoms including heavy menstrual bleeding. Again, no effects on surgical outcome were described .

Hysteroscopic surgery with conventional instruments

New developments in hysteroscopes and sheath were generally dominated by decreasing outer diameter (OD) without losing the quality of the image. Although newer hysteroscopes provide separate inflow and outflow channels, the inflow channel is often also designed as the working channel for the introduction of surgical instruments. In case of a very small OD, the small fluid inflow channel can be partly obstructed by the introduced instruments causing impaired irrigation, distension and visualisation. Therefore, further downsizing the OD of hysteroscopes should not impair channel size any further; more can be expected from the introduction of an optical chip technology in hysteroscopes.

An assortment of rigid, semi-rigid and flexible instruments has been developed or adapted for hysteroscopic surgery. The rigid and semi-rigid instruments include scissors, grasping forceps and biopsy forceps. It is obvious that only very small fibroids (<1 cm) can be treated with such conventional instruments with a diameter of 3–7 French. During diagnostic preoperative hysteroscopic procedures, a myoma can possibly be incised around its border at the transition to the normal myometrium in order to promote the expulsion of the myoma towards the uterine cavity, eventually resulting in less intramural extension . Some authors state that hysteroscopic myomectomy with conventional (no electrosurgical) use of instruments (cold-loop resection) is a safe and effective procedure of notable importance for fertility patients .

Resectoscopy

The resectoscope for hysteroscopic use is a modification of the urologic resectoscope. Its first use for the removal of a submucous myoma was described in 1978 by Neuwirth . Its assembly requires practice, and it should be mastered before surgical procedures are undertaken. The sheath has an OD of 7–9 mm, and it includes both inflow and outflow ports for distending media. The resectoscope is equipped with a continuous flow, and it provides excellent irrigation for operative procedures. If surgical debris or the so-called ‘tissue chips’ block the operative field, the resectoscope can be removed while the sheath is left in place. This allows for the removal of large tissue while maintaining cervical dilation. Electrosurgical instruments or electrodes can be inserted into an attachment to a spring handle that allows the surgeon to move the surgical electrode inward and outward.

In case of monopolar high-frequency electrosurgery, the patient must be grounded, and a nonelectrolyte, nonconducting distending media must be used. The more modern bipolar resectoscopes are used with saline distending media. Although bipolar techniques are less hazardous related to intravasation and electrolyte blood disbalances, more gas bubbles may hamper visualisation, and gas emboli might even cause spasms in the lung capillaries potentially disturbing gas diffusion in the lungs.

Electrocautery and laser

Electrocautery instruments, such as a needle or a button (mushroom) electrode, have been adapted for the hysteroscope or resectoscope. They can be used for excision or vaporisation of submucous myomas. Vaporisation has the disadvantage that the tissue is no longer available for pathologic examination. Bipolar electrodes are preferred nowadays as they have the same less hazardous intravasation risks as resectoscopy with the use of saline for irrigation and distension of the cavity.

Lasers (neodymium–yttrium–aluminium–garnet (Nd:YAG), potassium titanyl phosphate (KTP) and argon) offer no advantages over electrocoagulation. As these lasers are more expensive and more dangerous, their use has almost disappeared.

There are no significant new developments in electrocautery instruments or lasers. The main disadvantage of bipolar compared to monopolar electrodes is the higher number of gas bubbles that are created, and they disturb visibility. Although the industries are improving the electrodes, the problem has not been solved completely.

Tissue removal systems (hysteroscopic morcellation)

Tissue that has been cut must be removed from the uterine cavity by taking out the hysteroscope after grasping the loose tissue elements with a forceps or the loop electrode in case of the resectoscope. Although the removal of tissue under visual control, instead of using a curette, is the most effective way, it takes a large number of steps that can be tiring in the long run, inconvenient to perform and consequently found hard to learn. For these reasons, operative hysteroscopy has a rather long learning curve, and the number of gynaecologists who perform operative hysteroscopy is still too low. So, there is a need for alternative techniques that are easier to learn and can be performed with less experience and risk.

Hysteroscopic morcellation could resolve some of the above-mentioned difficulties. The first tissue removal system TRUCLEAR™ (Smith & Nephew, Andover, MA, USA) was invented by the author, and it is based on an instrument that consists of a set of two metal hollow rigid tubes that fit in each other. The inner tube rotates within the outer tube, driven mechanically by an electrically powered control unit and controlled by a foot pedal that activates the rotation and regulates the direction of the rotation of the inner tube. The control unit is connected to a handheld motor drive unit in which the morcellator is inserted. Both tubes have a window opening at the end with cutting edges. By means of a vacuum source connected to the inner tube, the tissue is sucked into the window opening and it is cut and ‘shaved’ as the inner tube is rotated . The system uses no electrocoagulation, and there is no lateral thermal or electrical energy spread. Haemostasis occurs by a spontaneous myometrial contraction. The removed tissue is discharged through the device, is collected in a tissue trap and is available for pathological analysis. As only one introduction is needed, the number of perforations is extremely low. The 4.0-mm morcellator is introduced into the uterine cavity through a straightforward working channel of a continuous-flow 8–9-mm rigid hysteroscope. After dilatation of the internal os (internal orifice) of the uterine cervix, atraumatic insertion is accomplished with the use of an obturator in the outer sheath of the hysteroscope. Saline solution is used for distension and irrigation.

Van Dongen et al. performed an RCT to compare conventional resectoscopy and hysteroscopic morcellation among residents in training . The mean operating time for resectosocpy and morcellation was 17.0 (95% confidence interval (95% CI): 14.1–17.9; standard deviation (SD): 8.4) and 10.6 (95% CI: 7.3–14.0; SD: 9.5) min, respectively ( p = 0.008). Subjective surgeon and trainer scores for the convenience of a technique on a visual analogue scale were in favour of the morcellator.

A new development in hysteroscopic morcellation is the recent availability of a smaller OD TRUCLEAR™ system with a 2.9-mm cutting-blade and a 5.0-mm hysteroscope for an office or ambulatory use with no or local anaesthesia. Polyps, small myomas and retained products of pregnancy can be removed in that way. The very similar morcellator system Myosure™ was introduced a few years later by Hologic (Bedford, MA, USA). In a recent review of the Manufacturer and User Facility Device Experience (MAUDE) database, both tissue removal systems were compared, and it was found that cases using Myosure™ (a single flow device) were complicated by adverse events five times higher than using TRUCLEAR™ . Another company that recently came with an alternative 9-mm OD morcellation device is Storz (Tutlingen, Germany).