Abstract
Uterine fibroids or leiomyomas are solid, invariably benign tumours of uterine smooth muscle and connective tissue. The prevalence varies according to the population studied, but is estimated to be 25% in a general female population of reproductive age, although rates of up to 70% have also been reported [1–6]. Fibroids that encroach beyond the myometrium into the uterine cavity are referred to as submucosal, submucous or intracavity, and may account for up to 10% of all fibroids [7]. They are thought to be associated with abnormal uterine bleeding and reproductive failure. The development of endoscopy has allowed removal of submucosal fibroids under direct vision, hysteroscopic myomectomy, which avoids the need for laparotomy or crude, blind intrauterine techniques.
12.1 Introduction
Uterine fibroids or leiomyomas are solid, invariably benign tumours of uterine smooth muscle and connective tissue. The prevalence varies according to the population studied, but is estimated to be 25% in a general female population of reproductive age, although rates of up to 70% have also been reported [1–6]. Fibroids that encroach beyond the myometrium into the uterine cavity are referred to as submucosal, submucous or intracavity, and may account for up to 10% of all fibroids [7]. They are thought to be associated with abnormal uterine bleeding and reproductive failure. The development of endoscopy has allowed removal of submucosal fibroids under direct vision, hysteroscopic myomectomy, which avoids the need for laparotomy or crude, blind intrauterine techniques.
Hysteroscopic myomectomy is emblematic of what constitutes ‘operative’ hysteroscopy. Submucosal fibroids (SMFs) are common, with an estimated prevalence of 7–22% in women with heavy menstrual bleeding (HMB) and in approximately 5% of those with subfertility [8–11] or undergoing assessment for recurrent miscarriage. This type of fibroid is accessible endoscopically without the need for an incision, a true example of natural orifice transluminal endoscopic surgery (NOTES), which makes the approach attractive because morbidity is minimised and recovery rapid. However, the surgery can be difficult and lead to serious complications [12] and poor outcomes. An understanding of the indications and the importance of diagnostic pre-operative preparation and treatment planning is therefore mandatory. Moreover, awareness of the attributes of the available equipment, development of proficiency in several surgical techniques and an appreciation of achievable clinical outcomes is imperative if we are to best serve women with clinical conditions related to SMFs and optimise their prognosis.
12.2 Indications for Hysteroscopic Myomectomy
SMFs are thought to be associated with abnormal uterine bleeding (AUB), primarily heavy menstrual bleeding (HMB) [13–15] and reproductive failure, including subfertility and recurrent miscarriage [16–17]. Thus, the indications for hysteroscopic removal of SMFs are AUB refractory to medical treatment and otherwise unexplained reasons for reproductive failure. The rationale for the intervention relates to the impact the fibroid has upon the endometrium, either directly or indirectly, from a functional perspective. The underlying mechanisms are far from fully understood.
Epidemiological data and outcomes of surgical removal (see Section 12.8) support the role of SMFs in contributing to HMB [13–15] and reproductive failure [16–17]. The FIGO PALM-COEIN classification recognises the significance of SMFs in the aetiology of the condition [18]. In the case of reproductive failure, it is assumed that implantation of the embryo is compromised by the presence of a submucosal fibroid, leading to infertility and a propensity to miscarriage.
12.3 Diagnosis of Submucosal Fibroids and Treatment Planning
The aim of hysteroscopic myomectomy, regardless of the surgical modality used, is complete enucleation of the SMF, leaving behind no residual fibroid tissue. Diagnostic preparation is of key importance because it allows treatment to be planned, women to be counselled about what to expect and surgical outcomes in terms of safety and efficacy to be optimised.
From a diagnostic perspective, hysteroscopy and hysterosonography are more accurate than 2D transvaginal ultrasound (TVS) or blind endometrial biopsy in the diagnosis of SMFs [19]. The addition of 3D imaging during TVS does not improve the accuracy of TVS or hysterosonography [20]. Magnetic resonance imaging (MRI) is less practical and costs associated with routine use are prohibitive.
12.3.1 Transvaginal Ultrasound
The size and intramural component of the SMF are the main drivers of surgical complexity and most important predictors for prognosis. Transvaginal imaging is therefore an important test because these attributes of the SMF can be assessed. The deeper the fibroid extends within the myometrium, the more difficult hysteroscopic surgery will be and the more varied the treatment outcomes [21]. While standard 2D TVS provides lower diagnostic accuracy for SMFs compared with hysteroscopic assessment [19] (see Section 12.3.2), it does provide important information about the actual dimensions of the fibroid and the proximity of the fibroid to the serosal surface of the uterus; the so-called ‘myometrial free margin’. If this margin is 5–10 mm then a cautious hysteroscopic approach by an expert may be considered.
Some SMFs are ‘transmural’, extending into both the endometrial and serosal uterine surfaces (Figure 12.1) [18]. Indeed, the utility of a hysteroscopic approach to myomectomy is contentious where the myometrial free margin is <5 mm [22]. In such circumstances, laparoscopy or laparotomy may be preferred. In the future, pre-operative imaging using cutting edge computer software may allow pre-procedural ‘virtual hysteroscopy’ in planning subsequent surgery.
12.3.2 Outpatient Hysteroscopy
Direct endoscopic visualisation of the SMF is the gold standard diagnostic test [19, 23]. Hysteroscopy can discriminate between SMFs and other focal uterine lesions. Moreover, key characteristics of the SMF can be recorded. These include estimates of its size, the intramural proportion of the fibroid (based upon the angle between the intracavity fibroid and endometrial surface), surface area relative to the uterine sidewall and overall cavity, surface vascularity and location (Figure 12.2). These features are useful for classification (see Section 12.4) and are important because they allow surgical management to be planned and women to be properly counselled (Box 12.1)[21].
Figure 12.2 Hysteroscopic views of type 2 submucosal fibroids demonstrating the wide or obtuse angle between endometrium and fibroid, which protrudes into the cavity. This indicates that most of the fibroid is within the myometrium. An LNG-IUS lies alongside the fibroid in the image on the right.
Box 12.1 Information Key to Treatment Planning Provided by Pelvic Ultrasound and Outpatient Hysteroscopy
Complexity and Counselling
Technique
Need for pre-procedural preparation
Medical (hormonal)
Surgical (Office Preparation of Partially Intramural Myomas – OPPIuM)
Setting
Outpatient (office)
Day case
Modality
Miniature mechanical
Miniature electrode
Resectoscope
Hysteroscopic tissue removal system
In addition to the information provided by pelvic ultrasound and outpatient hysteroscopy, the patient’s history and clinical examination findings are important when planning treatment. Interventions to minimise collateral trauma or thermal injury to the endometrium should be prioritised in women requiring optimisation of reproductive function, as opposed to women with AUB who do not require future fertility.
One criticism of the assessment of submucosal fibroids by hysteroscopy is the impact fluid distension of the uterine cavity has upon the relationship between the uterine cavity and the myometrium. This effect of ‘sinking’ into the underlying myometrium is even more pronounced as fluid pressures rise with the use of larger diameter operative hysteroscopes [24] (Figure 12.3). The ‘disappearing fibroid’ is even more likely with medical pre-operative treatment using gonadotrophin-releasing hormone analogues (GnRHa).
Figure 12.3 (a) At relatively high intrauterine fluid pressure, the fibroid is pushed into the myometrium so that it can hardly be seen. (b) During the same hysteroscopic procedure, but with a lower fluid pressure, the fibroid is revealed and becomes more prominent.
12.4 Hysteroscopic Classification of Submucosal Fibroids
12.4.1 FIGO Classification
The FIGO classification, adapted from the original developed by Wamsteker et al. and propagated by the European Society of Gynaecological Endoscopy (ESGE), is the most widely used (Table 12.1) [18, 25]. This recognises that the relative degree of myometrial involvement is the primary determinant of both the feasibility and the prognosis of hysteroscopic myomectomy. The classification can be used with pelvic ultrasound to aid standardisation, comparison and treatment planning. The classification is simple to remember and use but does have limitations, including the subjectivity inherent in assessing the proportion of the SMF within the underlying myometrium. The angle between the side of the fibroid at the junction with the endometrium has been proposed as a way of objectifying the assessment; acute angle (<90°) = type 1 fibroid and obtuse angle (>90°) = type 2 fibroid. Furthermore, the existence of a type 0 fibroid is debatable, given that all uterine fibroids arise from the myometrium and so must have some intramural component, however small, making them ‘pedunculated’ type 1 fibroids.
| Type | Cavity:myometrial relationship | Hysteroscopyb |
|---|---|---|
| 0 | 100% in the cavitya | Pedunculated |
| (0% in the myometrium) | ||
| 1 | >50% in the cavity | Angle <90° between the fibroid and its attachment to the cavity surface |
| (<50% in the myometrium) | ||
| 2 | ≤50% in the cavity | Angle >90° between the fibroid and its attachment to the cavity surface |
| (≥50% in the myometrium) |
a All submucosal fibroids by definition are derived from the myometrium such that there will always be a myometrial component (allowing us to question the existence of a ‘type 0’ fibroid), but these fibroids are pedunculated and can be removed ‘flush’ with the surface of the uterine cavity
b Transvaginal ultrasound allows type 1 and 2 fibroids to be distinguished. The diagnosis of type 0 fibroids is facilitated by saline or gel contrast (hysterosonography)
12.4.2 ‘STEP-W’ classification
The STEP-W (size, topography, extension, penetration, wall) classification developed by Lasmar [26] is a more comprehensive pre-operative classification of submucosal fibroids, where a score is generated that indicates the degree of surgical complexity (Table 12.2). In addition to recording the FIGO degree of myometrial penetration, this nomenclature considers other parameters: the extension of the base of the fibroid with respect to the wall of the uterus, the size of the visible intracavity fibroid, the surface area of the base of the fibroid with respect to the uterine wall and its location. A better correlation with surgical outcomes is claimed, namely completeness of the myomectomy, duration of surgery and fluid deficit, than with the simpler FIGO classification [21]. External validation is required before this classification can become more widespread.
Table 12.2 STEP-W classification of submucosal fibroids [26]
| Criterion | Definition | Score |
|---|---|---|
| Size | ≤2 cm | 0 |
| >2–5 cm | 1 | |
| >5 cm | 2 | |
| Topography | Low | 0 |
| Middle | 1 | |
| Upper | 2 | |
| Extension of the base | ≤⅓ | 0 |
| ⅓–⅔ | 1 | |
| >⅔ | 2 | |
| Penetration | 0% | 0 |
| ≤50% | 1 | |
| >50% | 2 | |
| Lateral wall | Absent | 0 |
| Present | 1 | |
| Total scorea | Summation | 0 (minimum)–9 (maximum) |
a Total score:
0–4 = low complexity
5–6 = high complexity (consider GnRHa or ulipristal acetate; higher likelihood of multi-stage procedures)
7–9 = consider alternative medical, radiological or surgical treatments
12.5 Pre-operative Preparation
12.5.1 Medical Preparation
Endometrial Thinning and Fibroid Shrinking
Medical treatment is often prescribed for two to three months prior to surgery to down-regulate the endometrium. The hormonal treatments include progestogens, danazol or GnRHa that render women amenorrhoeic. This practice has the advantage of allowing women to take iron supplements and build up their iron stores pre-operatively, potentially reducing surgical morbidity. Moreover, the surgical view is enhanced in the absence of blood and endometrial debris, and perioperative endometrial congestion – the oedematous changes from absorption of fluid distension media – is prevented.
GnRHa are most effective in thinning the endometrium and also have the advantage of reducing the volume (by 30–50%) and vascularity of the submucosal fibroid by inducing a hypo-oestrogenic state. However, they are associated with further side effects as a consequence of oestrogen deficiency. These include troublesome menopausal symptoms and cervical stenosis, making cervical dilatation more problematic, causing genital tract trauma or even preventing access to the uterine cavity. More recently the selective progesterone receptor modulator ulipristal acetate (UPA) has been shown to induce amenorrhoea and shrink fibroids pre-myomectomy without inducing an oestrogen-deficient state [27, 28].
Despite these potential advantages, data on surgical feasibility (e.g. duration, completeness), safety (e.g. fluid absorption, uterine trauma) and prognosis (clinical outcomes) are inconsistent when hormonal preparation is compared with no pre-operative medical intervention [29–32]. Some authors argue that recurrence is higher following GnRHa administration because small fibroids may no longer be visible, distorting the endometrial surface because of shrinkage and possibly because of a higher propensity for the fibroid to ‘sink’ into a less elastic myometrium with uterine hydrodistension. Furthermore, data comparing GnRHa with UPA to guide clinical practice are presently lacking [33]. As a result, practice varies between gynaecologists, some with entrenched views for routine use, some who never use them (although they may advocate scheduling procedures when the endometrium is thinnest during the proliferative phase of the menstrual cycle) and others who adopt a more pragmatic approach of using hormonal pre-treatment when a higher level of surgical complexity is anticipated.
Antibiotics
Antibiotics should not be routinely prescribed prior to hysteroscopic procedures, including hysteroscopic myomectomy, because there is no evidence to support their use [34, 35]. Endometritis following resectoscopic myomectomy affects 1 in 200 women [35].
Cervical Preparation
There is a lack of robust evidence supporting the unequivocal use of cervical preparation using oestrogen (in post-menopausal women), prostaglandins (e.g. misoprostol), osmotic dilators (e.g. laminaria tents) or vasopressin; no overall benefit has been shown for the practice in enhancing the feasibility, safety or patient experience of hysteroscopic myomectomy [36–38]. Clinicians may decide to use such measures on an individual basis, where cervical dilatation beyond Hegar 6 (6 mm) is anticipated, but a policy of routine use cannot be recommended [39].
12.5.2 Surgical Preparation
The increasing use of outpatient hysteroscopy in the diagnostic workup of SMFs and technological advances in miniature instrumentation have led to interest in treating SMFs in an outpatient setting. However, unlike endometrial polyps, SMFs are vascular and originate from the well-innervated myometrium. Thus, their removal in this setting is generally limited to smaller lesions (most frequently, accessible FIGO type 0 fibroids), using mechanical or electrosurgical means. However, the intramural component of submucosal fibroids spontaneously migrates into the cavity to a varying degree once the overlying endometrium has been incised; this observation has resulted in the notion of a ‘two-stage’ procedure, where FIGO type 1 and 2 fibroids are surgically prepared in advance of subsequent definitive removal [40, 41]. This surgical preparation consists of making an incision over the endometrial mucosa covering the fibroid using 5 Fr scissors or a 5 Fr bipolar electrode, without anaesthesia. The incision proceeds along the reflection line on the uterine wall, up to the cleavage plane between the fibroid and its pseudocapsule. The idea is that during subsequent menstrual cycles, myometrial contractions will partially or wholly expel the intramural component of the fibroid, rendering it more accessible and amenable to removal. Limited data suggest the feasibility of the technique, but firm conclusions regarding its impact upon the completeness of subsequent hysteroscopic myomectomy and prognosis cannot be made at present. Smaller fibroids, <3 cm, and those located on the anterior/posterior walls as opposed to lateral or fundal placed fibroids, seem to be more successfully enucleated.
12.6 Hysteroscopic Myomectomy
12.6.1 Surgical Equipment
Equipment fundamental to the practice of contemporary hysteroscopic surgery is detailed in Chapter 3. Figures 3.9, 3.10, 3.11 and 3.12 show examples of the different treatment modalities.
12.6.2 Choice of Technique
The choice of approach will vary according to several factors detailed in Box 12.2. Adverse features include the presence of cervical stenosis, an enlarged cavity limiting illumination and uterine distension, multiple, large fibroids (>3 cm diameter), fundal location, myometrial penetration >50% (FIGO type 2) or the serosal surface within 5 mm of the fibroid. Solitary, small FIGO type 0–1, non-fundal submucosal fibroids are the most straightforward to remove. In the presence of a stenosed or narrow and fibrous cervix, small-diameter instruments (e.g. miniature electrodes, some tissue removal systems or mini-resectoscopes) may be preferred in order to avoid genital tract trauma. Greater precision is required in women requiring future fertility so that thermal damage to the endometrium is minimised. While patient characteristics should not necessarily influence the chosen technique, co-morbidities may determine the choice of treatment setting, anaesthesia and duration of the procedure, including the threshold set for fluid deficit [42, 43].
Box 12.2 Determinants of Technique
Operator
Experience
Preference
Infrastructure
Equipment – resectoscopes; mini-electrodes; tissue removal systems
Fluid management – gravity; pressurised; automated systems
Setting
Operating theatre
Outpatient room
Uterine characteristics
Cervical stenosis
Cavity size
Fibroid characteristics (see FIGO and STEP-W classifications)
Myometrial penetration – FIGO types 0–2; myometrial free margin on USS
Location – upper, middle or lower cavity; sidewall or fundal basal attachment
Size – largest diameter; volume; surface area of the basal attachment
Number
Presenting complaint
Abnormal uterine bleeding – reproductive age; post-reproductive age
Reproductive problems – subfertility; recurrent miscarriage; pre-term delivery
12.6.3 Techniques for Intracavitary Fibroid Removal
Use of 5 Fr Instruments for Small Fibroids
This method utilises a straight 5 Fr bipolar electrode (see Figure 3.9) that is placed at the distal extremity of the fibroid. A retrograde surgical cut is made to the proximal extremity, at the level of attachment of the fibroid to the myometrium. This can be repeated on the other side. Systematic vertical and horizonal cuts are made in the same furrow (gentle probing with the inactivated electrode can be used to help define the correct plane), delineating the fibroid capsule until the basal attachment with the myometrium is reached [44–46]. The fibroid can be removed en bloc in this way or alternatively an additional series of vertical and horizontal cuts (e.g. cutting into quarters; ‘hot cross bun’ technique) made before final enucleation to debulk the fibroid and aid its retrieval from the cavity. Ideally, the cut pieces should be small enough to remove with 5–7 Fr hysteroscopic grasping forceps or biopsy cups, although this is not always possible given the dense nature of fibroid tissue.
Resection With Loop Electrode
A monopolar or bipolar cutting loop (see Figure 3.11) is placed beyond the distal border of the basal attachment of the fibroid, activated with a cutting current and then always moved from the fundus towards the cervix and never in the reverse direction. Systematic, repeated movements – by moving the hysteroscope or withdrawing the cutting loop, or a combination of both methods – are undertaken until the fibroid is removed; this is known as transcervical resection of fibroids (TCRF) [13–15, 38, 47] (Figure 12.4, Video 12.1). Attempts may be made during the procedure to cauterise specific bleeding points using the loop with a coagulating current if the bleeding persists and compromises visualisation.
Related posts:
Chapter 2 – Anatomy and Physiology of the Uterus
Chapter 3 – Infrastructure and Instrumentation for Hysteroscopy
Chapter 9 – Complications of Hysteroscopic Surgery
Chapter 8 – Hysteroscopic Electrosurgery
Chapter 17 – Audit, Data Collection and Clinical Governance in Hysteroscopy
Chapter 18 – Training in Hysteroscopic Skills
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