Endometrial Polyps and Sonohysterography

A transvaginal sonogram demonstrates a rounded echogenic mass within the endometrium

Sonohysterography confirms the mass to be predominantly intracavitary with a narrow base

Findings:

A transvaginal sonogram in a patient with vaginal bleeding demonstrates a focal rounded echogenic mass in the region of the uterine cavity in the sonogram on the left. The sonohysterogram on the right clearly demonstrates the mass projecting into the uterine cavity. This was resected and proved to be an endometrial polyp.

Discussion:

The two most common indications for sonohysterography are abnormal uterine bleeding and infertility. Patients frequently have had a transvaginal sonogram demonstrating an abnormal or focally thickened endometrium. While many consider endometrial biopsy and dilatation and curettage to be the "gold standard" for diagnosis, they are costly and often fail to detect endometrial disease. The sonohysterogram can help triage the patient to the appropriate next step of diagnosis. When a focal polyp or intraluminal myoma is detected hysteroscopic resection is an appropriate consideration. Diffuse endometrial thickening, however, can be sampled with endometrial biopsy or dilatation or curettage. Some clinicians are skilled at the use of hysteroscopy which is highly diagnostic and can be performed within the office setting. It should be remembered however that hysteroscopic resection is a surgical procedure, performed in the operating room. Thus sonohysterography may obviate the need for diagnostic hysteroscopy and allow for appropriate patient triage. A recent study by Alatas et al compared the diagnostic accuracy of transvaginal sonography, hysterosalpingography, sonohysterography and hysteroscopy. There was no statistical difference between them in their ability to detect uterine abnormalities. Sonohysterography was more sensitive compared with transvaginal sonography and hysterosalpinography (90.9% vs 36.3% and 72.7% respectively). While sonohysterography may also be used to detect endometrial cancer, not all studies have demonstrated high sensitivity or specificity in doing so. A recent report by Bernard et al failed to accurately diagnose three of five endometrial cancers in their study. These three cancers were misdiagnosed as endometrial hypertrophy, endometrial polyp and a submucosal myoma. However, all were diagnosed as a uterine abnormality and thus treated with resection.

The initial step in performing sonohysterography should be to explain to the patient the major risks of the procedure, including infection and pain. While some patients may experience mild discomfort, extreme pain or infection are uncommon. Most centers do not administer prophylactic antibiotics, however examinations in patients with active infection should be delayed. The timing of the study will depend upon the indications and the patients menstrual status. Infertility patients are best examined just after the cessation of menses in the proliferative phase when the endometrium is normally thin. When myomata are suspected, examination during the secretory phase will often allow better visualization of the myomata and their relationship to the endometrium. Occasionally sonohysterograms performed in the luteal phase may cause shearing of the endometrium resulting in the misinterpretation of endometrial polyps.

 

Sonohysterographic Technique

Sonohysterographic catheter (arrow) has been inserted into the uterine cavity

Under sonographic guidance with the transvaginal transducer, the balloon is inflated and gently pulled into the lower uterine segment

* Both illustrations reproduced with permission from: Cullinan JA, Fleischer AC, Kepple DM, Arnold AL. Sonohysterography: A technique for endometrial evaluation. Radiographics 15:501-514, 1995

Prior to imaging the patient it is often advisable to perform a bimanual examination to assess uterine position and tenderness. Subsequently, a standard transvaginal examination is performed to assess the uterus and adnexa. The transvaginal transducer is withdrawn and a standard speculum is inserted and the cervix is cleansed with an antiseptic (10% iodine-based) solution. A sonohysterography catheter is then inserted into the cervical os. Inspection and preparation of the catheter should take place prior to insertion. If a balloon catheter is chosen then it should be filled and emptied with 1-2 cc of saline to test for leaks. Likewise the catheter itself should be flushed and prefilled with saline to get rid of all air bubbles which will lead to artifactual echoes. The catheter is inserted into the midbody or fundus of the uterus and the speculum is carefully withdrawn. A vaginal probe is then inserted and the catheter is withdrawn under observation into the lower uterine segment / cervical area and the balloon distended. Saline is then injected into the catheter (usually 5-10 cc or whatever is necessary to distend the uterine cavity enough to adequately evaluate the endometrium) and images are obtained and recorded. The uterus should be scanned in both longitudinal, sagittal as well as coronal planes of section.

The balloon has been deflated so that the endometrium can be seen in its entirety. Catheter (arrow)

Prior to the cessation of the procedure, the balloon should be deflated and the catheter should be pulled back to the cervix to adequately examine the lower uterine segment and cervix. In addition to observation of the endometrium for its thickness and focal abnormalities, the myometrium should be observed for pathological changes, most often myomata.

Adhesions within the uterine cavity can often be demonstrated with sonohysterography. These may appear as thin or thickened, irregular septa traversing the uterine cavity. Endometrial polyps usually appear as echogenic predominantly solid masses projecting into the uterine cavity. The glandular tissue within the polyps may become markedly dilated and filled with proteinaceous fluid. These dilated glands likely account for the cystic areas often seen within endometrial polyps. Cystic areas should not however be considered pathognomonic of polyps. Cystic areas may be seen within the endometrium of patients with cystic hyperplasia of the endometrium and endometrial atrophy. The stalk to the polyp may either be thin or broad based. Using color Doppler flow imaging, frequently a single "feeding" vessel to the polyp may be identified.

Endometrial polyp with a broad based attachment with the endometrium

Color Doppler flow imaging demonstrating the vascular supply within the polyp's stalk

Submucosal leiomyoma indenting the adjacent endometrium

Leiomyomata may either be intramural, exophytic or submucosa. Perhaps the greatest utility of sonohysterography is in demonstrating the size and relationship of a mass to the endometrium and its potential for hysteroscopic resection. At times the differentiation between endometrial polyps and myomata may be difficult, particularly if a endometrial polyp is broad based. However, this may not alter management as both lesions will likely be resected surgically. Lastly, it should be remembered that measurements of the endometrium frequently reported in the literature are bilayer measurements and one should make sure that measurements that are using to reach a conclusion about abnormal thickness are comparable to reported data.

 

References:

Goldstein SR. Saline infusion sonohysterography for the patient with abnormal bleeding. Applied Radiology 33-36, Oct. 1997

Lindheim SR. Sonohysterography: Nascent applications. OBG Management 46-56, October, 1997

Hulka CA, Hall DA, McCarthy K, Simeone JF. Endometrial polyps, hyperplasia, and carcinoma in postmenopausal women: Differentiation with endovaginal sonography. Radiology 191:755-758, 1994

Alatas C, Aksoy E, Akarsu C, Yakin K, Aksoy S, Hayran M. Evaluation of intrauterine abnormalities in infertiele patients by sonohysterography. Human Reproduction 12:487-490, 1997

Bernard JP, Lecuru F, Darles C, Robin F et al. Saline contrast sonohysterography as first-line investigation for women with uterine bleeding. Ultrasound Obstet. Gynecol 10:121-125, 1997

Cullinan JA, Fleischer AC, Kepple DM, Arnold AL. Sonohysterography: A technique for endometrial evaluation. Radiographics15:501-514, 1995

Goldstein SR. Use of ultrasonohysterography for triage of perimenopausal patients with unexplained uterine bleeding. Am J Obstet Gynecol 170:565-570, 1994

Lev-Taoff AS, Toaff ME, Liu JB, Mertn DA, Goldberg BB. Value of sonohysterography in the diagnosis and management of abnormal uterine bleeding. Radiology 201:179-184, 1996

Laughead MK, Stones LM. Clinical utility of saline solution infusion sonohysterography in a primary card obstetric-gynecologic practice. Am J Obstet Gynecol 176:1313-8, 1997

 

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