Uterine Fibroids (Leiomyoma, Myoma)

Localization of Fibroids

Fibroids can occur in any part of the uterus. They can appear on the cervix and the corpus in the broad ligament. The general classification of fibroids is based on their localization and is divided into intramural, submucosal, and subserosal fibroids. Intramural myomas are located in the muscle part or myometrium of the uterus. If the tumor progresses in the uterine cavity, it is called submucosal myoma (Figs 18 and 19) and if it is just under the serosa, it is called subserosal myoma (Fig. 20).

The symptoms associated with fibroids depend on the location and size of the tumor mass. Myomas are often asymptomatic and are detected on routine examination. The most common symptom caused by fibroids is uterine bleeding, which is usually in the form of either menorrhagia or hypermenorrhea. Larger fibroids are associated with pain and bloating in the abdomen. In myomas, infarction can be severe and may cause severe pain, like in the acute abdomen of any cause. Depending on their localization, urinary incontinence, constipation, and dyspareunia may occur. Interestingly is the fact that submucosal fibroids are the least frequent (only 5%) but are accompanied by the greatest consequences in terms of symptoms such as uterine bleeding, as well as it’s negative impact on reproduction in women.

Classifications of the Leiomyoma

Therefore, there are several types of classifications that aim to localize the tumor itself preoperatively. The most commonly used one now is by FIGO PALM-COEIN classification 7.

SM Myoma

Submucous (SM) fibroids are subdivided into type 0 (completely intracavitary) (Fig. 23). Type 1 (being <50% of the mean diameter intramural) (Fig. 24), and type 2 (at least 50% intramural) (Fig. 25).⁸ There are two options for diagnosis of submucosal leiomyomas: 2D and 3D ultrasound. The 2D ultrasound detects an initial pathological change, and an image of leiomyoma protrusion into the uterine cavity is easily obtained, but it can be underestimated or overestimated if the image is not in the right projection. 3D gives a much better image and can correct this lack of 2D ultrasonography,⁹ noting that analysis in recent studies has shown that 3D ultrasonography does not give an ideal clear picture of protrusion into the intracavitary space (protrusion of <50% was generally overestimated, and fibroid protrusion of greater than 50% was generally underestimated compared to hysteroscopy.¹⁰ On the other hand, a study comparing the preoperative hysteroscopic lasmar score with the 3D ultrasonographic lasmar score can be obtained from 3D ultrasound. A 3D ultrasound is best done in the luteal phase.¹¹

SIS and SM Leiomyoma

One method that can give a clearer picture, especially in small intramural myomas, is SIS. The technique of this method is based on injecting contrast into the uterine cavity during the examination with vaginal ultrasonography. This shows the whole interior better and the one determined by subtle pathology. It is better to perform it in the first phase of the cycle, that is, immediately after the end of the menstrual bleeding.

Both 2D and 3D transvaginal sonography can be combined with SIS to improve the contrast between the myometrium, fibroid, and uterine cavity. Regarding the 3D SIS studies, they prove that 3D SIS is associated with more successful resection of submucosal leiomyomas because preoperative ultrasound findings are very precise in terms of location, the ratio of the endometrium to the myometrium of the leiomyoma itself (Figs 26 to 28).^12,13

Intramural Leiomyoma

Federation of Gynecology and Obstetrics type 3 leiomyomas are totally intramural but also contact the endometrium. Type 3 is formally distinguished from type 2 with hysteroscopy using the lowest possible intrauterine pressure necessary to allow visualization (Fig. 29). Type 4 lesions are intramural leiomyomas that are entirely within the myometrium, with no extension to the endometrial surface or to the serosa (Fig. 30).⁸ Intramural myomas are the most prevalent of all the leiomyomas (58–79%) occurrence, with a median growth rate of 35.2% by volume per year, and have a higher yearly volumetric increase of intramural myomas compared to either subserosal or SM myomas. There is no significant evidence of a negative impact of fibroids on female reproduction, but there are studies that indicate that reproduction is compromised when there exist intramural leiomyomas (especially >4 cm in diameter), primarily due to the presence of uterine contractions in fibroids,¹⁴ the size of the fibroid¹⁵ and the distance from the edge of the fibroid to the endometrium¹⁶ have a negative impact on embryo implantation and live birth rate. In type 4 fibroids, it is essential to mention the minimum inner and outer free margin to decide the route of surgery.

Subserous Leiomyoma

Subserous (types 5, 6, and 7) leiomyomas represent the mirror image of the SM leiomyomas—with type 5 being at least 50% intramural (Fig. 31), type 6 being <50% intramural (Figs 32 and 33), and type 7 being attached to the serosa by a stalk that is also ≤10% or the mean of three diameters of the leiomyoma (Fig. 34). In type 8, is reserved for leiomyomas that do not relate to the myometrium at all and would include cervical lesions (demonstrated), those that exist in the round or broad ligaments without direct attachment to the uterus, and other so-called “parasitic” lesions (Fig. 35).⁸ The existing data on the effects of subserosal fibroids on fertility support the conclusion that subserosal leiomyomas do not have any adverse effects on the fertility potential of women and no adverse effect on assisted reproductive technology outcome.¹⁷ This conclusion is further supported by the fact that no beneficial effect on fertility is noted when myomectomy is performed for subserosal leiomyomas.¹⁸

Hybrid Leiomyomas

Classification of lesions that are transmural is categorized by their relationship to both the endometrial and the serosal surfaces. The endometrial relationship is noted first, with the serosal relationship second (Figs 36 and 37).⁸

Unlike previous classifications such as ESGE (European Association for Gynecological Endoscopy), the type 3 where the intramural myoma touches the area of the endometrium, cavitation distortion, also in the group of subserosal fibroids introduces new subgroups.⁸ This is important because this system provides a basic framework for deciding on surgical treatment of fibroids, that is, which lesions should be operated on and, of course, important information on the possible use of resection endoscopy in subserosal fibroids, which according to this system in this type of fibroids does not work in patients with infertility.

In addition to these two important data provided by ultrasound, of course, other variables such as the size and number of fibroids and, of course, the topography of the tumor seen not only in terms of uterine parts such as the cervix, lower or upper segment but also the anteroposterior and lateral orientation of the tumor itself and proximity to blood vessels, provides valuable preoperative data.¹⁹ Vaginal ultrasonography can also detect myomas of 5 mm in diameter, but it is limited in terms of detection of the number and size of the tumor mass. Namely, it is considered that the volume of the uterus or the tumor itself over 375 mL or several four or larger myomas requires a combined approach of transvaginal and transabdominal ultrasonography in the detection of the leiomyomas (Figs 38 and 39).²⁰

Other methods for the diagnosis and assessment of fibroids are hysteroscopy and magnetic resonance imaging, but ultrasound remains the first and most cost-effective method in screening the population for the detection of this pathology. In general, the results of the comparative study show the excellent performance of vaginal ultrasound in detecting fibroids compared to other methods, where a vaginal ultrasound showed a sensitivity of 83% and specificity of 90%.^16,20 In addition to the above, the ultrasound should answer important solutions. One is to make a differential diagnosis, that is, to differentiate fibroids from other pathologies of the uterus, which are most often adenomyosis and endometrial polyps, and the second is to recognize the possible malignant potential of these tumors. It is important to recognize adenomyosis because the therapeutic proximal differs from that of myoma.⁷ There are cases where the structure of adenomyosis is similar, almost identical to fibroids, but vascularization is different; fibroids have strong circumferential vascularization of the pseudocapsule, while in adenomyosis it is more homogeneous and it is translesional (Fig. 40).⁷ Endometrial polyps are more difficult to differentiate from submucosal fibroids. However, in polyps, there is a hyperechogenicity similar to that of the unicorn in the secretory phase and often a vascular loop (Figs 41 and 42).^7,21 A rare pathological condition is uterine angioma. Hemangioma should be detected before deciding on hysteroscopic resection due to expected increased bleeding during surgery (Figs 43 and 44).²²