Applied Radiology

Dr. Bree is a radiologist with Radia Medical Imaging and the Medical Director Medical Imaging at Providence Everett Medical Center, Everett, WA.

Postmenopausal vaginal bleeding is a common clinical problem. Postmenopausal bleeding (PMB) is caused by endometrial cancer in approximately 10% of patients, although in some patient populations, this percentage is as high as 30%. ¹ Transvaginal sonography (TVS) along with endometrial biopsy (EMB) have become the standards in the evaluation of patients with PMB. A consensus conference sponsored by the Society of Radiologists in Ultrasound (SRU) developed a complete, clinically useful algorithm for the evaluation of patients with PMB beginning with EMB or with TVS. ² The following case presentation illustrates the use of these techniques to evaluate patients with PMB efficiently.

Case Report

A 70-year-old woman who had been menopausal for 18 years presented to her family physician with intermittent vaginal spotting. She did not have a history of diabetes or obesity, conditions which predispose women to endometrial cancer. She had not been on hormone replacement therapy for several years. Her family physician performed an EMB, which yielded tissue insufficient for diagnosis.

Imaging Findings

She was then referred for ultrasound evaluation, which was performed using Sequoia equipment (Acuson, Mountain View, CA). Initially, a transabdominal scan was performed with a 4-MHz probe with tissue harmonics. This showed a thickened endometrium measuring 1.8 cm (Figure 1). Transvaginal scanning with an EC10C5 endoluminal probe demonstrated similar findings with the suggestion of a small cystic space within the endometrium (Figure 2). Cystic spaces can be seen with endometrial polyps. The radiologist, recognizing the need to make a more definitive diagnosis in this patient, suggested saline-infusion sonohysterography (SIS), which was performed using a balloon catheter immediately following the TVS.

Following visualization of the cervix with a lighted speculum, the catheter was inserted into the endometrial cavity. Approximately 15 mL of sterile saline was instilled and gray-scale and color Doppler images were obtained. The study showed a large homogeneous soft-tissue mass in the endometrium with a relatively thin attachment (Figure 3). Color Doppler evaluation of the mass demonstrated a single central vessel (Figure 4), which was diagnostic of an endometrial polyp. At hysteroscopy, a polyp was discovered and removed successfully. There was no recurrence of the vaginal bleeding.

Discussion

A number of studies have been performed to define the role of transvaginal ultrasonography and endometrial biopsy in patients with PMB. ^1-5 The results of studies have consistently shown that a sonographically measured endometrial thickness of 5 mm or less almost completely excludes endometrial carcinoma. In most of the studies, endometrial biopsy was found to have a high sensitivity for the detection of endometrial cancer, approaching 95% when there was an adequate sample. ^1-5 SIS has been shown to be useful for evaluating the endometrium, particularly in patients with PMB. Even when the endometrial thickness is 5 mm or less, SIS can identify an anatomic cause of the bleeding accurately. ^4-6

Postmenopausal vaginal bleeding is an important and common problem. The data in older gynecology and radiology literature suggest that anatomic reasons for bleeding are less common than endometrial atrophy, which is a diagnosis made when no anatomic cause is found. ⁷

More recently, however, the results of several studies indicate that anatomic causes of PMB, such as polyps, leiomyomata, and hyperplasia, are more common than had been previously thought. Prior to the use of hysteroscopy, dilatation and curettage (D&C) was the primary surgical diagnostic tool for PMB. Because it is a blind procedure, D&C does not enable confirmation of the presence of benign disorders, although it is excellent for enabling the detection of endometrial carcinoma. ⁸

With the recent availability of hysteroscopy and SIS, more benign anatomic abnormalities are being found in women with PMB. Many of these abnormalities are polyps and fibroids, and these may account for the abnormal bleeding. In a multicenter study investigating the utility of SIS, Bree et al ⁴ reported polyps in 47%, leiomyomata in 11%, and endometrial hyperplasia in 4% of women with PMB. Most of the remainder of the patients in the study had a normal and thin endometrium, with a single layer thickness of 2.5 mm or less. These patients probably had endometrial atrophy as the etiology of the bleeding, although that is currently a diagnosis of exclusion. Proving absence of cancer and potential premalignant diagnoses, such as hyperplasia and large polyps with atypia, is reassuring, and an important benefit of performing SIS in these patients.

The SRU consensus panel on PMB was very useful in collating the opinions and experience of a number of specialists in gynecology and ultrasound on the appropriate evaluation of patients with PMB. The panelists agreed that either TVS or EMB is an adequate first-line test. Transabdominal sonography alone is not recommended for this evaluation. A transvaginal sonogram can be called normal only if the entire endo-metrium can be seen in a linear fashion from fundus to cervix. The endometrium must be uniformly thin, and measure 5 mm or less throughout its length. With a normal TVS or normal and adequate EMB, further evaluation may not be necessary if the presence or absence of cancer is the paramount issue. If either TVS or EMB is inadequate or abnormal, but not obviously a cancer, further testing with SIS, hysteroscopy, or D&C is warranted. The choice of a follow-up examination is dependent on whether the abnormality is focal or diffuse. Focal abnormalities will benefit from SIS or hysteroscopy. With diffuse abnormalities, SIS is still useful, but D&C alone may be able to make the correct diagnosis. A minority of panelists thought that all women with PMB should undergo SIS. ²

Bree et al ⁴ studied the accuracy and outcomes of using TVS and SIS in a series of 98 patients with PMB. Using pathology and 6-month follow-up as proof, the study resulted in a sensitivity of 98%, specificity of 88%, positive predictive value of 94%, and negative predictive value of 97%. They showed that in a majority of cases, clinical decision making and diagnostic confidence, as measured by a survey of the treating physicians, was affected positively by the imaging results. These decisions included confirmation of the treatment decision already made, as well as change in management from surgical to nonsurgical, and nonsurgical to surgical. In another outcomes study evaluating cost-minimization algorithms for different strategies for evaluating PMB, Medverd and Dubinsky ⁹ demonstrated that algorithms using ultrasound, including SIS, were less expensive than those using biopsy and hysteroscopic procedures.

There are a number of diagnostic choices for evaluating patients with PMB. Testing that begins with ultrasound seems to have the best overall patient acceptance, accuracy, and lowest cost. In patients who are at significant risk for endometrial cancer, it is very appropriate to perform an EMB initially and, if positive, move on to definitive therapy. Since cancer is seen in only approximately 10% of patients with PMB, most other patients would benefit from an approach using ultrasound. *