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The Institute for Advanced Medical Education designates this enduring material for a maximum of 1 AMA PRA Category 1 Credit™. Physicians should only claim credit commensurate with the extent of their participation in the activity.
These credits are accepted by the American Registry for Diagnostic Medical Sonography (ARDMS).
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Estimated Time for Completion: approximately 1 hour
Date of Release: April 24, 2006
Date of Last Review: April 25, 2015
Expiration Date: April 24, 2018
In compliance with the Essentials and Standards of the ACCME, the author of this CME tutorial is required to disclose any significant financial or other relationships they may have with commercial interests.
Dr. Lyndon Hill discloses no relevant financial interests with commercial interests.
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In the premenopausal female, endometrial thickness and sonomorphology reflect the functional status of the ovaries. Transvaginal sonography without fluid contrast cannot adequately evaluate the echogenic endometrium of the secretory phase (Fig. 1). In the postmenopausal patient, transvaginal sonography (TVS) can be used to narrow the differential diagnosis of vaginal bleeding. By detecting an atrophic endometrium (? 4 mm), TVS reduces the need for invasive diagnostic testing1. Sonohysterography enhances transvaginal sonographic imaging of the postmenopausal endometrial cavity if vaginal bleeding recurs.
In premenopausal patients, saline infusion sonohysterography should be performed after menstrual bleeding, but before day 8 of the menstrual cycle. At the beginning of the menstrual cycle the endometrium has not grown sufficiently to have an irregular appearance that might result in a false positive diagnosis of endometrial pathology. In women with short or highly irregular cycles, it is best to use a form of birth control prior to the procedure in order to ensure that an early intrauterine pregnancy is not interrupted.
A speculum is inserted into the vagina and the cervix prepped with betadine or hibicleans in the iodine sensitive patient. A sonohysterographic catheter is filled with sterile normal saline prior to insertion into the endometrial cavity. This reduces the amount of air introduced into the endometrial cavity when the saline is instilled.
The catheter is threaded into the endometrial canal. Occasionally, cervical adhesions or the direction of the endocervical canal will prevent the insertion of the catheter. The introduction of the end of a sterile Q-tip into the cervical canal will break up any adhesions and also determine the appropriate angle for catheter placement. A 5.0 French pediatric feeding tube will provide an adequate bolus of saline to evaluate the endometrial cavity. Characteristically, the patient will note a slight cramping when the pediatric feeding tube reaches the uterine fundus. By measuring uterine length before the procedure, the examiner will know how far the catheter should be inserted to reach the fundus. The insertion of additional catheter will interfere with endometrial cavity visualization and may result in kinking of the catheter that obstructs flow. For infertility studies in which tubal patency must also be evaluated, a balloon tipped catheter is required.
Once the catheter is in place, the speculum is removed and the transvaginal transducer is inserted. A 20 ml syringe containing sterile normal saline is attached to the catheter. Instillation of the sterile normal saline is begun slowly under direct sonographic visualization. When the endometrial cavity remains filled with fluid, additional injections of sterile saline are not required (Fig. 2). If the endometrial canal collapses immediately upon instillation of normal saline then a larger bolus of fluid is required. In addition, the transvaginal transducer should be used to manipulate the uterus in an attempt to reduce the egress of fluid. The latter modifications to the technique will usually permit adequate visualization of the endometrial cavity. When visualization is still sub-optimal, the pediatric feeding tube should be removed and a balloon tipped catheter used in its place.
Extreme obesity and impaired flexibility of the hips are factors that may prohibit a sonohysterogram2. The procedure cannot be performed in the presence of true cervical stenosis. In patients with significant uterine retroversion, partially filling the bladder or manipulating the uterus with the transvaginal transducer may straighten the uterus enough to permit catheter placement.
While minimal discomfort when the catheter reaches the uterine fundus or with saline instillation can occur, severe pelvic pain should not be experienced. Patients may occasionally become dizzy or nauseous during, or immediately after, the procedure.
Infection is an acknowledged, but rare, complication of sonohysterography3. The administration of prophylactic antibiotics is controversial3,4. Bonnamy et al5 has recommended prophylactic antibiotics for all patients with infertility. The limited amount of fluid utilized to evaluate the endometrial cavity and low intrauterine pressures achieved when a non-occluding catheter is used minimizes the risk of infection. The utilization of a balloon tipped catheter to evaluate the fallopian tubes has a theoretically higher potential of tubal infection. I, therefore, utilize prophylactic antibiotics in these cases. If the endometrial cavity must be assessed in a patient with hydrosalpinges, prophylactic antibiotics are also recommended4.
Endometrial polyps are a common cause of menometrorrhagia. VanBogaert6 has reported a 23.8% prevalence of polyps in patients with menometrorrhagia. The highest incidence of endometrial polyps in patients with menometrorrhagia is in the fifth decade of life (29.3%). Endometrial polyps are also associated with infertility. The prevalence of polyps in infertile patients ranges between 5% and 44%7,8,9. The prevalence of polyps in asymptomatic women is 1.2%10. There is an association between endocervical and endometrial polyps. Coeman et al11 reported a 26.7% incidence of endometrial polyps in patients with cervical polyps.
The risk of malignant transformation of an endometrial polyp is approximately 0.5%12 to 0.8%13. Older age, menopause, and polyps > 1.5 cm are associated with an increased of malignancy13,14. Smaller polyps have been reported to slough with menstruation12.
A heightened awareness of the sonographic appearance of endometrial polyps may result in their presumptive diagnosis without sonohysterography. Transvaginal sonography in the proliferative phase of the menstrual cycle should suggest the presence of a polyp when a hyperechoic density is noted in the endometrial stripe (Fig. 3)15. In addition to being echogenic, polyps may also have cystic components12 . The bright edges of a sharp interface between the endometrium and polyp is a sonographic marker that permits the diagnosis of a polyp without sonohysterography (Fig. 4). Caspi et al16 reported a sensitivity, specificity, and positive predictive value of 96%, 82%, and 93%, respectively for the "bright edge sign" of an endometrial polyp.
Since a secretory endometrium is hyperechoic, it tends to obscure endometrial polyps. Transvaginal sonography has a sensitivity of 33.3%17 in the detection of endometrial polyps versus 84% for sonohysterography18 (Fig 5).
Color Doppler is a useful adjunct to sonohysterography - polyps generally have a single feeding vessel (Fig 6), while uterine leiomyomas have several vessels19.
Tamoxifen is used as adjunctive therapy for breast cancer in postmenopausal women. Most postmenopausal women treated with tamoxifen will have an endometrial thickness > 4 mm due to the estrogen agonist effect of the medication. In view of this known estrogenic effect of tamoxifen on the endometrium, an endometrial thickness ? 8 mm is considered within the normal range in postmenopausal women on this medication20.
There is an increased prevalence of the following endometrial lesions with tamoxifen use: endometrial hyperplasia; polyps; adenocarcinoma; and subendometrial sonolucencies in the proximal myometrium. Since the junctional area is not clearly defined, the intramyometrial cysts may be erroneously included in the measurement of the endometrial thickness (Fig. 7). Sonohysterography is particularly helpful in differentiating between intramyometrial cysts and possible endometrial pathology. In the 8% of patients on tamoxifen with an atrophic endometrium and subendometrial sonolucencies, additional invasive testing is not required20.
If a patient on tamoxifen has vaginal bleeding, sonohysterography should be considered, regardless of the endometrial thickness. Saline infusion sonohysterography should also be performed in patients on tamoxifen with vaginal bleeding and a negative endometrial biopsy. Hann et al20 found endometrial pathology in 12 of 19 (63%) sonohysterograms performed on women on tamoxifen with a negative endometrial biopsy.
Sonohysterography is more effective and acceptable than office hysteroscopy for detecting endometrial pathology in postmenopausal women who are on tamoxifen. In a study by Timmerman et al21 19% of office hysteroscopies failed, accounting for the low sensitivity of this technique in the evaluation of the endometrium.
Leiomyomas may obscure visualization of the endometrial lining. It is difficult for conventional transvaginal sonography to determine whether a centrally located leiomyoma is in the uterine cavity or in the myometrium adjacent to the cavity22,23. The site and depth of attachment of a submucous or intracavitary leiomyoma (Fig. 8) is important when planning its surgical excision.
Sonohysterography is equivalent to hysteroscopy in detecting submucous leiomyomas22,23. An advantage of sonohysterography is that this technique can determine the intramural component of submucous leiomyomas. If a leiomyoma is entirely intracavitary or extends into the myometrium < 50% (Fig. 9), the patient is a candidate for hysteroscopic resection. For leiomyomas that extend > 50% into the myometrium, transcervical resection should only be attempted in specific cases24.
The addition of saline to the endometrial cavity improves visualization of an endometrium obscured by leiomyomas25 and improves interobserver agreement with respect to describing the location of leiomyomas26.
Rapid growth of leiomyomas due to tamoxifen therapy has been described27.
On transvaginal sonography endometrial hyperplasia characteristically appears as a thickened, echogenic endometrium and may contain tiny cysts (Fig. 10). However, hyperplasia may be detected in endometrial linings measuring < 5 mm1 . With sonohysterography focal or generalized hyperplasia can be distinguished based on the irregular boundaries of the uterine cavity caused by hyperplasia28,29. Localized areas of hyperplasia may resemble endometrial polyps. Sonohysterography can also be used to evaluate the endometrium after the medical management of hyperplasia28. In postmenopausal patients with a thickened endometrial lining, a biopsy can yield scant tissue, insufficient for diagnosis. In this particular case, sonohysterography is particularly helpful in evaluating the entire uterine cavity and localizing a specific site for biopsy.
Sonohysterography has been found to be as accurate as hysteroscopy in the detection of endometrial hyperplasia30.
On saline sonohysterography an endometrial carcinoma may present as a mass, an irregular thickening of the endometrium or be indistinguishable from endometrial hyperplasia (Fig. 11a). In contrast to a polyp, power Doppler reveals multiple vessels entering an endometrial carcinoma (Fig. 11b). One characteristic that has been commented upon by several authors is the poor distensibility of the endometrial cavity with saline infusion31. It should be emphasized that sonohysterography does not play a significant role in diagnosing endometrial carcinoma. The diagnosis of endometrial carcinoma is usually based on an endometrial biopsy in a patient with postmenopausal bleeding.
Color Doppler is a useful adjunct to sonohysterography - polyps generally have a single feeding vessel (Fig 6), while uterine leiomyomas have several vessels19.
There has been some concern about the theoretical risk of transporting malignant cells into the peritoneal cavity during saline infusion. Alcázar et al32 performed saline infusion sonohysterography with an 8-French pediatric Foley in 14 patients with Stage I endometrial carcinoma at the time of laparotomy. There was not any spillage of fluid from the fallopian tubes in 9 patients. Malignant cells were detected in the fluid obtained from the peritoneal cavity of 1 of the remaining 5 patients (1 in 14; 7.1%). The viability of the cells that were flushed through the tubes was not assessed. The lower pressure infusion of saline with a patent cervix (i.e., utilization of a pediatric feeding tube) should carry a lower theoretical risk of cell dissemination to the peritoneal cavity33.
On conventional transvaginal sonography, a subtle irregularity of the endometrial lining in the proliferative phase suggests that an adhesion may be present. When the uterine cavity is distended with fluid, synechiae are more easily detected. Adhesions should be described as filmy (Fig. 12) or dense. In addition, the extent of cavity involvement should be recorded. Saline infusion sonohysterography has a 75% sensitivity and 93% specificity for the detection of uterine adhesions29,34,35,36.
While sonohysterography is an improvement over the traditional two-dimensional technique, 3-D has a higher sensitivity and specificity for the delineation of specific uterine anomalies (Fig. 13a and b)37. 3-D ultrasound also reduces the interobserver variability in the diagnosis of uterine anomalies38.
Three-dimensional sonohysterography improves the overall evaluation of the uterine cavity. This technique also better delineates the location of endometrial pathology39. The coronal plane is the most useful for displaying the location of a lesion in the endometrial cavity (Fig. 14)40.
Infertility investigations have traditionally included x-ray hysterosalpingography (HSG) or laparoscopy for the assessment of tubal patency. Sonohysterography is an alternative technique.
When tubal patency is evaluated, a balloon tipped catheter is required to appropriately distend the endometrial cavity and to force fluid out of the fallopian tubes into the cul-de-sac. The infused saline should be shaken in the syringe - the bubbles that result are easier to see passing through the fallopian tubes. Color Doppler assessment of the fallopian tubes has also been used to document tubal patency (Fig. 15). More recently, ultrasound contrast agents have been employed to assess tubal patency41.
In the presence of bilaterally occluded fallopian tubes, the uterine cavity will expand with only a limited instillation of saline and will not decompress. Patients will invariably complain of discomfort from the uterine pressure. The demonstration of true unilateral occlusion, in contrast to cornual spasm, cannot be determined during sonohysterography. The rapid egress of fluid through the fallopian tube with the least resistance can be interpreted as a unilateral occlusion42.
Sonohysterography can appropriately triage patients with vaginal bleeding into those that can be treated medically and those that require operative hysteroscopy. Polyps may be present in postmenopausal females with bleeding and an endometrial thickness < 5 mm. Hence, if bleeding persists, sonohysterography is warranted, regardless of the thickness of the endometrium on transvaginal sonography43.
The advantages of sonohysterography over other methods to assess the endometrial cavity include improved sensitivity/specificity in the detection of pathology. When compared to other modalities (hysterosalpingogram in the premenopausal patient or office hysteroscopy in the postmenopausal patient), the advantages of sonohysterography include: cost; avoidance of radiation; and patient comfort.
The determination that endometrial disease is focal or global improves the accuracy of subsequent biopsy. While diffuse endometrial disease can be biopsied blindly, focal abnormalities require a visually guided biopsy.
Sonohysterography not only assists in determining the diagnosis or therapeutic approach, it may also reduce or eliminate the need for surgical intervention.