Scholarly article on topic 'Ultrasonography of Uterine Leiomyomas'

Ultrasonography of Uterine Leiomyomas Academic research paper on "Clinical medicine"

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Journal of Medical Ultrasound
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{fibroids / ultrasound / variants}

Abstract of research paper on Clinical medicine, author of scientific article — Sabrina Q. Rashid, Yi-Hong Chou, Chui-Mei Tiu

Abstract Leiomyomas or myomas of the uterus, also known as a fibroid uterus, are the most common tumors of the uterus. They are benign neoplasms of smooth muscle origin with various degrees of fibrous connective tissue. These tumors can develop in any part of the female genital tract where there is smooth muscle or fibrous tissue, even in the ovary, broad ligament, and vagina. They need to be differentiated from adenomyosis and intracavitary polyps. They mostly remain asymptomatic but sometimes they cause significant morbidity. In such situations, hysterectomy or other surgical intervention is indicated. On ultrasonography, most uterine leiomyomas typically appear as well-defined, solid masses. Their echogenicity is usually similar to that of the myometrium, but sometimes they are hypoechoic. They often show some posterior acoustic shadowing. Variants of leiomyomas occur when they undergo cystic degeneration, hyalinization, or calcification. In such situations, determining a diagnosis is sometimes difficult. Magnetic resonance imaging can be used in this situation for an accurate diagnosis.

Academic research paper on topic "Ultrasonography of Uterine Leiomyomas"

Journal of Medical Ultrasound (2016) 24, 3-12

Chinese Taipei Society of Ultrasound in Medicine


Ultrasonography of Uterine Leiomyomas

Sabrina Q. Rashid 1*, Yi-Hong Chou 2*, Chui-MeiTiu 2

1 Bangladesh Specialized Hospital, Department of Radiology and Imaging, and University of Science and Technology Chittagong, Dhaka, Bangladesh, and 2 Department of Radiology, Taipei Veterans General Hospital and National Yang Ming University, Taipei, Taiwan

Received 2 February 2012; accepted 23 December 2015 Available online 20 April 2016

Abstract Leiomyomas or myomas of the uterus, also known as a fibroid uterus, are the most common tumors of the uterus. They are benign neoplasms of smooth muscle origin with various degrees of fibrous connective tissue. These tumors can develop in any part of the female genital tract where there is smooth muscle or fibrous tissue, even in the ovary, broad ligament, and vagina. They need to be differentiated from adenomyosis and intracavitary polyps. They mostly remain asymptomatic but sometimes they cause significant morbidity. In such situations, hysterectomy or other surgical intervention is indicated. On ultrasonography, most uterine leiomyomas typically appear as well-defined, solid masses. Their echogenicity is usually similar to that of the myometrium, but sometimes they are hypoechoic. They often show some posterior acoustic shadowing. Variants of leiomyomas occur when they undergo cystic degeneration, hyalinization, or calcification. In such situations, determining a diagnosis is sometimes difficult. Magnetic resonance imaging can be used in this situation for an accurate diagnosis.

© 2016, Elsevier Taiwan LLC and the Chinese Taipei Society of Ultrasound in Medicine. This is an open access article under the CC BY-NC-ND license ( licenses/by-nc-nd/4.0/).






Conflicts of interest: The authors have no financial and nonfi-nancial conflicts of interest to declare.

* Correspondence to: Sabrina Q. Rashid, Bangladesh Specialized Hospital, 88 DOHS Banani, Dhaka Cantonment, Dhaka 1206, Bangladesh. Yi-Hong Chou, 201, Department of Radiology, Taipei Veterans General Hospital and National Yang Ming University, Section 2, Shih-Pai Road, Taipei 11217, Taiwan.

E-mail addresses: (S.Q. Rashid), (Y.-H. Chou).


"The uterus is an organ that should bear something, if not a child, then a fibroid"—so goes a saying. It is the most common tumor of the uterus and all pelvic organs. Uterine myomas or fibroids occur in 20—50% of women and represent the most frequent gynecologic tumor [1,2]. They are more frequent and occur at a younger age in the black population. Depending on their location and size, they may or may not be symptomatic [3].

Ultrasonography (USG) is usually the first method used to examine the female pelvis. Both transabdominal scan (TAS) and transvaginal scan (TVS) should ideally be


0929-6441 /© 2016, Elsevier Taiwan LLC and the Chinese Taipei Society of Ultrasound in Medicine. This is an open access article under the CC BY-NC-ND license (

Figure 1 Submucosal and degenerative myoma on the transvaginal scan. The mass is indicated by the arrows.

performed. A TAS is very difficult to perform in obese patients and gives less information. For the diagnosis of small leiomyomas, TVS is more sensitive; it is also sensitive in detecting leiomyomas when the uterus is retro-flexed and/or retroverted. A TAS is generally superior to TVS in diagnosing a fundal myoma; however, TVS occasionally helps to exclude a fundal myoma that was indicated by TAS. In TVS, a large or pedunculated myoma may lie outside the field of view of a high frequency probe with short focal length. Ultrasonography is highly operator-dependent; therefore, in expert hands, the location of the leiomyomas and 5-mm small fibroids can be detected by TVS. Leiomyomas of the uterus are common tumors and previous observations and reports have resulted in well-recognized diagnostic categories, based on histological or gross differences [4].

Symptoms and signs

The symptoms and signs of a leiomyoma depend on its size and location. Submucosal myomas (Figure 1) may erode into the endometrial cavity and cause irregular or heavy bleeding, which may lead to anemia. Fertility may be affected by submucosal or intramural leiomyomas (Figures 2 and 3), which by their location may inhibit sperm transport down the tube and prevent adequate implantation or cause recurrent miscarriages. Large cervical leio-myomas (Figure 3) can prevent normal vaginal deliveries. Large leiomyomas can cause symptoms by pressure effect on adjacent organs such as the bladder (Figure 4), bowel, and ligaments of the pelvis. They may cause dysmenorrhea, dysuria, and constipation. Low back pain may be because of pressure on pelvic ligaments or the lumbar plexus. Acute pelvic pain may be caused by torsion or necrosis of a previously asymptomatic leiomyoma. They may be pedunculated and present as a separate pelvic mass. Cervical leiomyomas may pedunculate into the endocervical canal, where ulceration and hemorrhage are common [3].


A fibroid uterus is more correctly called a leiomyoma because it arises from the smooth muscle of the uterine wall. A leiomyoma is actually a mass of smooth muscle proliferation in a whorled spherical configuration. They are encapsulated by a pseudocapsule and separate easily from the surrounding myometrium [3]. Leiomyomas also may occur in extrauterine sites such as the fallopian tube, cervix, vagina (Figure 5), or ligaments of the pelvis. However, they are most common in the uterus.

Figure 2 Numerous small intramural leiomyomas (M) on the transvaginal scan.

Figure 3 An intramural leiomyoma (large arrows) and a large cervical leiomyoma (myo, small arrow) on the transvaginal scan.

Leiomyomas that occur in the uterine wall can be submucosal, intramural, or subserosal (i.e., adjacent to the endometrium) and can develop in the muscle layer or just beneath the serosa. The tumor can also pedunculate with a stalk connecting the uterus (Figures 6,7). Submu-cosal leiomyomas are usually clearly visible and separate from the endometrium on a TVS, but can be difficult to differentiate from polyps (Figure 8). Hysterosonography is a technique in which sterile saline is instilled into the uterine cavity via a transcervical catheter while performing a TVS. This method allows better visualization of the endometrium and is more accurate than the traditional TVS in detecting submucosal leiomyomas and in differentiating them from polyps [5].


Since the late 1970s, clinical ultrasonography has been the "gold standard" of uterine imaging. The advent of TVS in

Figure 4 A longitudinal transabdominal scan of a largecervical leiomyoma (arrows), which resulted in the patient's inability to empty the urinary bladder. U = uterus; UB = urinary bladder.

the 1980s solidified this position by providing a closer and more accurate ultrasound (US) appraisal of the uterus. Since the 1990s, improvements in computed tomography (CT) and hysterosalphingography (HSG), and rapid developments in magnetic resonance imaging (MRI) have allowed these modalities to complement the traditional sonographic evaluation [4].

Leiomyomas or fibroids of the uterus are common neoplasms and most are the conventional type and therefore easy to diagnose. Throughout the years, several histological subtypes have been described. Their importance is largely because of their resemblance in one or more aspects to leio-myosarcoma and the obvious potential for misdiagnosis [4].

Most uterine leiomyomas appear as well-defined solid masses. Their echogenicity is usually similar to the myo-metrium, but sometimes the echogenicity is hypoechoic. The tumors cause the uterus to become bulky or may change the uterine contour and make it irregular (Figure 3). Uterine leiomyomas often show some posterior acoustic shadowing (Figure 3); this finding is more prominent in fibroids that have calcification (Figure 9).

Leiomyomas with cystic degeneration may have a complex appearance (Figure 1). Color Doppler US typically shows circumferential vascularity [6]; however, leiomyomas that are necrotic or have undergone torsion will show a lack of blood flow [7]. Transvaginal color Doppler US can be used to study uterine blood flow and leiomyoma arterial supply. The color Doppler US depiction of uterine vascu-larity depends on several factors such as the sensitivity of the scanner and the age and parity of the patient. In non-medically suppressed women of childbearing age, myo-metrial vessels and spiral vessels within the endometrium during the luteal phase are present. Postmenopausal women typically have a relatively hypovascular myome-trium and endometrium [6]. Blood flow impedance [expressed as the resistance index (RI)], pulsatility index (PI), and blood velocity can be calculated. Increased blood velocity and decreased RI and PI in both uterine arteries occur in patients with uterine leiomyomas. The same technique has been used to study blood flow in the main

Figure 5 (A) Longitudinal and transverse transabdominal scans of a leiomyoma (mass) on the vaginal wall. (B) Longitudinal and transverse transvaginal scans also show leiomyoma (the arrows indicate the mass) on the vaginal wall. UB = urinary bladder.

arteries supplying identifiable leiomyomas. Diastolic flow in these arteries is always present and increased in comparison to uterine artery blood flow. The difference in uterine artery blood flow between patients with leiomyomas and healthy volunteers is statistically significant and may have predictable value in growth rate evaluation of a benign uterine mass [8]. It may be that detecting hypervascularity in combination with other sonographic findings can identify

undetermined uterine smooth muscle tumors that will require additional diagnostic evaluation before treatment. Combined gray-scale and color Doppler US may help distinguish a uterine leiomyosarcoma from a leiomyoma [9]. A high vascularity score yielded high sensitivity (100%) but a low positive predictive value (PPV; 19%). Considering only the presence of marked central vascularity achieved a sensitivity of 88% and a specificity of 96% with a 44% PPV.

Figure 6 Longitudinal and transverse transabdominal scans show a subserosal leiomyoma (arrow) on the fundus. UB = urinary bladder.

Figure 7 Pedunculated leiomyomas. (A) The tumor (arrow) has a thin stalk (arrowhead) connecting it to the uterine fundus (longitudinal TAS image). (B) The TAS image shows a leiomyoma

Adding the diameter > 8 cm or the characteristics of a single myometrial tumor to the presence of central vascu-larity, the PPV and K index improved (PPV, 60%; K index, 59%). When the diameter was > 8 cm, marked central vascularity and presence of cystic degeneration were considered together for the diagnosis of leiomyosarcoma. The sensitivity decreased (50%), but specificity (99%), PPV (57%), and the K index (56%) remained largely unchanged.

Diffuse leiomyomatosis is among the many variants of uterine leiomyoma with an unusual growth pattern that has been described [10]. This tumor, however, is characterized by uterine enlargement that is symmetric, the result of innumerable leiomyomatous nodules throughout the myometrium.

Another morphologic variant of leiomyoma is intravenous leiomyomatosis [11]; In this variant, the leiomyoma is within vascular spaces that lie outside a leiomyoma, which are often grossly visible. A newer relatively rare variant, the cotyledonoid leiomyoma [12], has been the subject of several recent case reports [13,14]. This entity is named because of its dramatic placenta-like gross appearance, which belies its otherwise benign nature. Leiomyomas of the uterus are often accompanied by degenerative changes such as hyalinization, myxoid change, and calcification [15].

Edema within these tumors is also another type of degenerative process which, when less severe, is often referred to as hydropic change [16] or hydropic degeneration [17]. Cyst formation can be an exaggeration of this process, and is associated with increasing amounts of edematous fluid in some tumors. Cystic change itself is a recognized degenerative phenomenon [4].

Most variant leiomyomas have been reported in patients in the latter phase of their reproductive life or in the perimenopausal period. They are entirely benign and the patient's prognosis is good [4].

Most uterine leiomyomas are benign, although some uterine leiomyosarcomas may arise from a subset of leio-myomas [18]. Only approximately 0.23—0.7% of apparently benign uterine leiomyomas are actually leiomyosarcomas, based on pathological examination [19,20].

Large leiomyomas can occasionally obstruct the ureters and cause secondary hydronephrosis. Therefore, an US examination should include the urinary tract whenever a large pelvic mass is identified. The diagnosis of uterine leio-myomas on US is usually reasonably straightforward, although focal adenomyosis can mimic a leiomyoma and a pedunculated uterine leiomyoma can sometimes be mistaken for an adnexal mass [21] (Figure 7A). When there is doubt about the origin of a pelvic mass at US, further evaluation with MRI should be performed.

Three-dimensional US (3D US) is a more recently developed technique. The 3D technique can be available for

(arrow) with a relatively thick stalk (arrowheads) connecting it to the uterine fundus. (C) The TVS and (D)CTscanofa pedunculated calcific leiomyoma (arrow). Another small leiomyoma is visible (cursors). The patient also has ascites due to peritoneal dialysis. CT = computed tomography; TAS = transabdominal scan; TVS = transvaginal scan; UT = uterus.

Figure 8 The transvaginal scan shows a polyp (arrows) in the endometrial canal and multiple intramural leiomyomas (M).

transabdominal or transvaginal scans. Three-dimensional US can provide a multiplanar display of the anatomy of the uterus. The uterus is displayed in the standard orientation,

and in the coronal, transverse, and sagittal planes (Figure 10). What is coronal on the 2D display is actually transverse to the uterus. The actual coronal plane on 3D (i.e., the C-plane) is coronal to the uterus, not to the female pelvis. In the 3D display of the uterus, the plane of acquisition is usually provided in addition to the multi-planar display in the 3D presentation. The US operator needs to rotate the volume to see the standard plane [i.e., transverse, sagittal, and coronal (C-plane)]. The display varies, depending on equipment and operator preference. Sagittal acquisition is generally superior to coronal acquisition. If the uterus is too large to get into one volume with the sagittal plane, the transverse plane can be used. Three-dimensional TVS is generally superior to 3D TAS [22]. Breath holding can improve data acquisition. During scanning, the orientation issue is very important, and the identification of the cervix and the right and left side is needed. Three-dimensional US is very good for volume measurement of uterine leiomyomas and vascularity assessment by using vascularity index or vascularity volume display [23] (Figure 11). In addition to the multiplanar mode, the volume data may be also utilized for a multislice mode, rendered display mode, thick slice mode, or other modes

Figure 9 (A) Leiomyoma (arrows) with calcific changes presents as bright spots within the mass on the transvaginal scan. (B) Transabdominal scan of curvilinear calcification in the periphery of a leiomyoma (arrows) in a pregnant female. F = fetus.

the uterus. Calcification in the fibroids can be detected by a CT scan. Degenerated fibroids may appear complex and contain areas of fluid attenuation. Calcification occurs in approximately 4% of fibroids [28], and is typically dense and amorphous. However, calcification can also be confined to the periphery (Figure 8) of the fibroid when it is believed to be secondary to thrombosed veins from previous red degeneration [28]. Furthermore CT scan can demonstrate secondary changes of the uterine fibroids such as degeneration, necrosis, and sacromatous transformation [29].

Magnetic resonance imaging

Magnetic resonance imaging (MRI) is the preferred method for accurately characterizing pelvic masses. It is more sensitive than US in identifying uterine fibroids [30], it does not involve the use of ionizing radiation, and it can demonstrate the zones of the uterus very well. Submucosal, intramural, and subserosal fibroids are well demonstrated, and very small fibroids and cervical fibroids can be detected by MRI. MRI sequences should include axial and sagittal T1W and T2W images. Compared to the myometrium, non-degenerated fibroids appear as well-defined low-signal intensity masses on T2W images and as isointense on T1W images [31].

Figure 10 A leiomyoma (arrows) on three-dimensional (3D) ultrasonography presents as a hypoechoic mass in the cervical region (TAS). (A) The original raw image on the sagittal scan. (B) The 3D image. TAS = transabdominal scan.

(e.g., invert mode). In patients with a distorted endometrium on 2D US, 3D hysterosonography may readily demonstrate submucosal leiomyomas, help distinguish a pseudopolyp or an endometrial polyp, and allow for accurate assessment of intrauterine abnormalities [23,24].

Hysterosonography is an important addition to TVS in the accurate delineation of submucosal and intracavitary leio-myomas [25]. A 3D TVS can be combined with saline instillation into the uterine cavity to complement diagnostic hysteroscopy for the assessment of a submucosal leiomyoma. There is a good overall agreement between diagnostic hysteroscopy and TVS in the diagnosis of sub-mucosal leiomyomas and in the assessment of myometrial extension of fibroids [25,26]. Three-dimensional saline contrast sonohysterography may provide even more information than conventional 3-D TVS in this aspect [27].

Computed tomography

CT is not the choice for the characterization of pelvic masses. A CT scan is limited by the similar signal attenuation by uterine fibroids and the normal myometrium. Uterine fibroids are often seen incidentally on CT scans that are performed for other reasons. The typical finding is a bulky, irregular uterus or a mass in continuity within or with

Hysterosalpingography and sonohysterography

Hysterosalpingography (HSG) remains an important radio-logic procedure in the investigation of infertility and is a commonly performed examination because of recent advances in reproductive medicine. Hysterosalpingography can demonstrate the morphology of the uterine cavity, the lumen, and the patency of the fallopian tubes. Because of the increased demand for HSG, physicians should be familiar with the HSG technique and the interpretation of HSG images.

After administering a radiopaque contrast medium through the cervical canal, the uterine cavity, and the patency of the fallopian tubes can be evaluated. A properly performed HSG can detect the contour of the uterine cavity and the width of the cervical canal. Further contrast medium injection will outline the cornua isthmic and ampul-lary portions of the tubes, and will show the degree of spillage [32,33]. Most leiomyomas are diagnosed by TAS, whereas submucosal leiomyomas are imaged as smooth filling defects in the uterine cavity. Differential diagnosis of a leiomyoma must include endometrial polyps or a possible pregnancy. Small intramural leiomyomas do not distort the endometrial cavity and are not visualized on HSG. Submu-cosal leiomyomas can provoke smooth filling defects, smooth muscle repression, or obstruction of the fallopian tubes only if they are in the lateral walls of the uterus [32].

Distinguishing a submucous myoma from an endometrial polyp is very important. Intracavitary fibroids tend to be larger than the polyps, and homogeneous hyperechoic masses in the uterine cavity observed by sonohysterography (SHG) are highly suggestive of endometrial polyps [34], Other studies using B-mode sonography suggest that a hyperechoic polypoid lesion in the uterine cavity is characteristic of an endometrial polyp. By contrast, the

v....217.51 cm'

MG [0,100) 33.433

Color Angio

VI (*) 2.994

Fl (0,100) 26.251

VFI (0,100) 0.736

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myometrial echogenicity of uterine fibroids tends to vary (e.g., hypoechoic, isoechoic, hyperechoic, or mixed), which may depend on the size and nature of the fibroid. Thus, SHG may enhance the echogenicity in these intra-cavitary masses of the uterus. A published study showed homogeneous hyperechoic polypoid masses occur significantly in patients with endometrial polyps. Another study using SHG also demonstrated that most submucosal fibroids were hypoechoic. Therefore, homogeneous hyperechoic masses in the uterine cavity on SHG are highly suggestive of endometrial polyps [35,36].

Rare types

Diffuse leiomyomatosis is a rare condition that consists of diffuse involvement of the myometrium by innumerable small leiomyomas, which result in symmetrical enlargement of the uterus. They are histologically benign, although there may be dissemination through the peritoneal cavity or occasionally metastasis to distant organs [28].

Lipoleiomyomas are rare fat-containing leiomyomas with a reported prevalence of 0.005—0.2% [37]. They are detected in 0.03—0.2% of hysterectomy specimens [38]. Lipoleiomyomas are benign and present with the same symptoms as uterine leiomyomas. The most likely cause may be fatty metamorphosis of the smooth muscle cells of a leiomyoma [25,39]. An intensely hyperechoic, avascular uterine mass is most often a fat-containing mass and is virtually diagnostic of a lipomatous uterine tumor or lip-oleiomyoma [40] (Figure 12). If pedunculated, they can be mistaken on imaging for ovarian dermoids. As leiomyomas enlarge, they can outgrow their blood supply and result in various types of degeneration (e.g., hyaline, cystic, myxoid, or red degeneration) and dystrophic calcification [41]. Cystic degeneration, which occurs in ~4% of leiomyomas, may be an extreme sequelae of edema [42]. Fibroids typically have a characteristic ultrasonographic appearance, although cystic degenerating fibroids can have variable patterns and pose diagnostic challenges [43], especially when a fibroid is an usually large cystic mass (Figure 13) or a pedunculated leiomyoma masquerading as an adnexal mass. Pedunculated leiomyomas should be considered in the differential diagnosis of a multilocular and predominantly cystic adnexal mass.

Differential diagnosis

Leiomyosarcomas are malignant tumors of the uterus. They may occasionally arise from a preexisting fibroid but usually occur de novo [18]. The patient classically presents with a pelvic mass that has had a recent or rapid increase in size [19]. They are typically large, heterogeneous masses

Vascularization Index

Vascularization Flow Index

Figure 11 The tumor volume, tumor vascularity, and vascularity index in a leiomyoma (arrows), assessed by using three-dimensional ultrasonography (3D US). (A) The

conventional transabdominal scan image shows a hypoechoic mass in the uterine body (arrows). (B) Based on 3D US volu-metry, the tumor volume is 217.51 cm3. (C) Tumor vascularity on 3D US obtained by power Doppler US. The right lower image shows 3D power Doppler angiography. (D) The vascularity index (VI) of the leiomyoma is 2.994 (flow index = 26.251, vascularization flow index = 0.786).

Figure 12 An intensely hyperechoic uterine mass (large arrows) on the transvaginal scan is a fat-containing mass (i.e., a lipoleiomyoma). Another submucosal leiomyoma is present (small arrows) and associated with the distortion of the endometrial echoes (arrowheads).

containing areas of hemorrhage. They usually have more ill-defined, irregular margins, compared to benign uterine leiomyomas [16]. Combined gray-scale and color Doppler US may help distinguish uterine leiomyosarcoma from leiomyoma [9].

Adenomyosis is the ectopic endometrial tissue within the myometrium. The US findings are relatively nonspecific. Sonographic features used in the diagnosis of adenomyosis consisted of two factors or more of the following: a mottled inhomogeneous myometrial texture, globular uterine enlargement, uterine wall thickening, small cystic spaces within the myometrium, and a "shaggy" indistinct endometrial stripe. A MRI scan may be helpful because leio-myomas tend to be round, well-defined, encapsulated masses. Adenomyosis is a poorly demarcated or diffuse area without distinct margins or shape [44].

Endometrial polyps typically appear as pedunculated endometrial masses and will usually demonstrate an intact overlying endometrial stripe. For differentiation from a submucosal leiomyomas, HSG can be used.

A pedunculated subserosal leiomyoma can sometimes be mistaken for an ovarian tumor. At times, a correct diagnosis is determined only at the time of surgery.

Myometrial contractions can be mistaken for uterine fibroids. However, the contractions are transient, and therefore the masses will disappear on subsequent scans.

Figure 13 Cystic fibroid. (A) The sagittal scan of the lower abdomen shows a large nearly completely cystic fibroid uterus (arrows) that measures 12 cm x 10 cm and mimics a huge gestational sac. It is in the body of the uterus of an unmarried 25-year-old woman with regular but very heavy periods and dysmenorrhea. (B) The transverse scan shows a solid component, 57 mm thick (arrows), that resembles placental tissue on one side of the cystic fibroid uterus. CX = uterine cervix; U = uterus; UB = urinary bladder.


The authors would like to thank Ms. Chih-Ping Chiu, senior research assistant, for her excellent assistance in the preparation of this article.


Leiomyomas are the most common tumors of the uterus and pelvis. They are benign but can cause significant morbidity. They may be detected incidentally when performing ul-trasonography for other reasons and are usually easily recognizable. However, degenerate fibroids can have an unusual echotexture. Knowledge of the various appearances of fibroids enables an accurate diagnosis and proper treatment. They are mostly diagnosed by ultrasonography; however, MRI can be more accurate.


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