Robotic Myomectomy
Alexander Kotlyar
Rebecca Flyckt
General Principles
Definition
Uterine leiomyomas are one of the most common problems encountered by the obstetrician/gynecologist with approximately 70% to 80% of reproductive-aged women eventually developing these benign myometrial tumors.1,2 The majority of leiomyomas do not cause any symptoms and are often only noted incidentally on imaging or surgical pathology. However, as they enlarge, uterine myomas can lead to bulk symptoms, abnormal uterine bleeding, and dysmenorrhea. In a smaller percentage of cases, especially when submucosal fibroids are identified, pregnancy loss and infertility can occur.3
Differential Diagnosis
Uterine adenomyoma or adenomyosis
Pregnancy
Hematometra
Malignancy: uterine leiomyosarcoma or carcinosarcoma
Endometrial carcinoma or metastases from primary malignancy
Endometrioma
Anatomic Considerations
When planning a myomectomy, myoma location, number, and size are the key anatomic factors used to determine the most appropriate surgical approach. Uterine myomas are classified as being present just underneath the serosal surface (subserosal), within the myometrium (intramural), or beneath the endometrial lining (submucosal). Fibroids that are completely within the uterine cavity with little intramural involvement are called intracavitary. Submucous myomas can be further subclassified as type 0 (completely intracavitary), type I (>50% of the myoma is intracavitary), and type II (>50% of the myoma is intramural). For myomas that are type 0 or type 1, a hysteroscopic approach is preferred. However, for type II myomas, a nonhysteroscopic procedure is most appropriate.
Nonoperative Management
To treat uterine leiomyomas, multiple nonsurgical strategies are available and these can at times be very successful. These nonsurgical options include expectant management, medical management, uterine artery embolization, and high-frequency magnetic resonance (MR)-guided ultrasonography. The choice of the method is dependent upon judicious consideration of the patient’s medical history, desire for future childbearing, risk of malignancy, and the chance for successful outcome based on myoma characteristics.
Medical management typically relies on hormonal methods to reduce abnormal uterine bleeding. Although many women obtain relief, especially when heavy menstrual bleeding is the predominant symptom, the chance for long-term treatment failure is relatively high. The first line in hormonal agents is combined estrogen–progestin oral contraceptives. Although these compounds will not restrict myoma growth or reduce uterine volume, in some patients they can effectively reduce monthly blood loss. Despite the presence of conflicting evidence, some studies have indicated that early exposure to combined oral contraceptives may actually increase the risk of fibroids later in life.4 Progestational compounds such as depo-medroxyprogesterone and the levonorgestrel-containing IUD are also often used to manage symptomatic uterine fibroids. Although the levonorgestrel IUD is FDA-approved for the treatment of heavy menstrual bleeding, it is not indicated for the treatment of uterine myomas, and in fact, having a myoma with any significant intracavitary component is a relative contraindication to the placement of an IUD. These agents are effective for mild symptoms and help reduce heavy menstrual bleeding via endometrial and uterine atrophy. Lastly, a newer oral nonhormonal formulation (tranexamic acid, an antifibrinolytic) has been used successfully in women with myomas and can reduce the volume of monthly blood loss by up to 30%.
Gonadotropin-releasing hormone (GnRH) agonists are a highly effective treatment for both abnormal uterine bleeding related to myomas as well as bulk symptoms. These agents lead to a hypogonadotropic state which results in a substantial reduction in monthly blood loss within 3 months of administration. It must be noted that following the administration of a GnRH agonist, there is typically an initial increase (“flare”) in the release of pituitary FSH and LH stores due to binding of the GnRH agonist to its pituitary receptors. These pituitary receptors subsequently become desensitized, with a resultant decline in FSH and LH secretion and clinical symptoms resembling menopause within a few weeks. Local effects on leiomyomas including direct inhibition of local aromatase p450 expression leading to decreased conversion of androgens to estrogens, which are thought to stimulate myoma growth. In addition, GnRH agonists can suppress myoma cell proliferation and induce apoptosis, which likely underlies their capacity to reduce myoma volume. A reduction in preoperative myoma size can make a laparoscopic approach more feasible and avert the need for laparotomy. GnRH agonists can also be useful for the short-term correction of anemia prior to surgery, as indicated by a Cochrane database review.5 However, long-term use is not recommended due to the significant side effects of the hypoestrogenic state, such as bothersome hot flushes, and possible osteopenia and osteoporosis. It is not recommended to use these agents for longer than 6 months.6
The remaining nonsurgical options, as with medical options, can offer some relief but do also have associated limitations. Uterine artery embolization (UAE) or uterine fibroid embolization (UFE) is the first of these approaches. These methods involve instillation of occlusive material bilaterally into the arteries feeding the myoma beds.7 This technique is not recommended for women who desire future childbearing as the effects on fertility and ovarian reserve are unclear. A newer method is the use of magnetic resonance imaging-guided focused ultrasound (MRGUS). Using MRI guidance, multiple ultrasound waves are focused to induce local tissue destruction. The latter method is best suited when the leiomyoma cannot be resected via other surgical methods.6 MRGUS has been associated with complications such as skin burns, fibroid expulsion, and persistent neuropathy; it is not currently widely used.8
Imaging and other Diagnostics
As with the evaluation of many forms of pelvic pathology, transvaginal ultrasound is often the initial basic imaging study obtained. Pelvic ultrasound allows for the basic identification and localization of leiomyomas (Fig. 7.3.1). Myomas typically appear as enlarged hypoechoic and/or heterogeneous masses with lobular contours. The amount of fibrous tissue versus smooth muscle tissue determines the degree of hypoechogenicity. Due to mass effects, myomas tend to compress the surrounding myometrial tissue, creating a pseudocapsule and a defined myoma border (Fig. 7.3.2). Due to myoma degeneration and necrosis, internal calcifications can cause shadowing and a
“venetian blind” effect with ultrasound waves. Characterization of submucosal and intramural myomas can be further enhanced with the use of three-dimensional (3D) ultrasound; however, the utility of this feature is dependent on sonographer experience.
“venetian blind” effect with ultrasound waves. Characterization of submucosal and intramural myomas can be further enhanced with the use of three-dimensional (3D) ultrasound; however, the utility of this feature is dependent on sonographer experience.
 Figure 7.3.1. Transvaginal pelvic ultrasound demonstrating 4 to 5 cm posterior myoma displacing the endometrium anteriorly. |
 Figure 7.3.2. Transvaginal pelvic ultrasound with visualization of posterior myoma but indistinct margins and unclear cavity involvement. |
To evaluate the uterine cavity, saline infusion sonohysterography (SIS) can be used to determine the degree to which the uterine cavity is occupied or impinged upon by a submucosal myoma. Knowing the degree of penetrance of a myoma can influence the choice of operative approach. SIS has a greater sensitivity and specificity than transvaginal ultrasound (85.4% and 98.2% for SIS, respectively).9
Magnetic resonance imaging (MRI) is an additional imaging modality to complement the aforementioned ultrasonographic techniques and is routinely used at our institution to assist in preoperative planning for myomectomy. MRI relies on the use of a magnetic field to change the spin of hydrogen atoms present in tissue and measures the radiofrequency waves emitted by those atoms. The strength of the signal is affected by the number of hydrogen atoms (i.e., the water content of a particular tissue). Water content will affect the tissue’s appearance on T1- and T2-weighted images, with tissues with high water content appearing brighter on T2-weighted imaging. T1-weighted images better depict fat and areas of hemorrhage. Myomas classically appear as dark, well-circumscribed areas on T2-weighted images. Cystic degeneration, however, leads to increased brightness in this image sequence.
MRI is useful for surgical planning, especially if a laparoscopic or robotic myomectomy is desired (Fig. 7.3.3). The advantages of MRI over TVUS is greater sensitivity (80% vs. 40%, respectively), especially when four or more myomas are present. Disadvantages include possible nonidentification of very small myomas (typically less than 0.5 cm3) and significantly increased cost compared to ultrasound. Computed tomography is typically not used to image myomas given the inferior soft tissue contrast relative to MRI and TVUS. However, it may be useful in identifying ureteric compression if this is a concern.10
 Figure 7.3.3. T2-weighted MRI images provide excellent fibroid “mapping” in preparation for a robotic approach. The endometrial cavity is well visualized using this technique and can be more easily avoided in the interest of future fertility. |
Preoperative Planning
Prior to performing any type of myomectomy, the surgeon must first address several issues:
The most common preoperative issue is anemia resulting from heavy menstrual or abnormal uterine bleeding. Given the known bleeding dysfunction associated with uterine leiomyomas, the most common form identified is iron deficiency anemia. Milder forms of anemia can be treated with supplemental iron either in oral or IV form.
As a second step in preoperative planning, treatment with a GnRH agonist such as leuprolide acetate can be considered for 3 months prior the procedure. This is used either to decrease uterine or myoma volume, or to reduce ongoing abnormal uterine bleeding and anemia.
Ruling out malignancy is essential prior to performing any myomectomy. Women with risk factors (e.g., greater than
6 months of irregular menstrual cycles or known anovulation, polycystic ovarian syndrome, obesity or insulin resistance, or thickened endometrium) should be sampled to rule out endometrial cancer. This is typically done using office endometrial biopsy to detect any underlying endometrial hyperplasia or cancer.
It is also essential to obtain appropriate imaging procedures to delineate the dimensions of the uterus and the number, size, and location of myomas, and other pelvic pathology. As outlined above, SIS or MRI is preferred versus traditional transvaginal ultrasonography.
Surgical Management
The decision to proceed with surgical treatment for uterine leiomyomas is based upon several factors. These include:
Any associated abnormal uterine bleeding or heavy menstrual bleeding that is not responsive to conservative measures
Ongoing growth following menopause or any suspicion of malignancy
Infertility secondary to distortion of the endometrial cavity or fallopian tubes
Recurrent pregnancy loss (especially with known distortion of the endometrial cavity)
Diminished quality of life due to pain or pressure symptoms
Chronic blood loss leading to ongoing iron deficiency anemia
In choosing robotic myomectomy versus other techniques, multiple factors must be considered as outlined in Table 7.3.1.
Table 7.3.1 Comparison of Myomectomy Techniques | ||||||||||||||||||||||||
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