Endometrial assessment by transvaginal ultrasonography and correlation with histopathology among post menopausal women

Copyright: This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Background: Transvaginal ultrasonography has increased the reliability of imaging diagnosis of women with endometrial pathologies and this technique has become widely used to evaluate endometrial thickness in women with postmenopausal bleeding.


INTRODUCTION
Pelvic ultrasound has been used to evaluate the uterine cavity for fibroids, endometrial thickness, endometrial homogeneity and the presence of abnormal vascularity within the endometrium. The technique has been demonstrated to be reproducible and reliable. 1 However, thereafter many studies have been conducted on the use of transvaginal sonography (TVS) and this technique has become widely used to evaluate endometrial thickness in women with postmenopausal bleeding. 2 TVS is an easy, fast and cheap technique to exclude pathologic conditions in the endometrium. The threshold of 5 mm endometrial thickness effectively excludes endometrial abnormalities in postmenopausal patients and even patients on hormone replacement therapy. [3][4][5] The hallmark of endometrial pathology are heterogeneity and high echogenicity of the endometrium. 6 As per WHO classification, endometrial epithelial precursors are hyperplasia without atypia and atypical hyperplasia. 7 Endometrial epithelial tumors are endometrioid carcinoma, mucinous carcinoma, serous carcinoma, clear cell carcinoma, neuroendocrine tumor, mixed cell adenocarcinoma, undifferentiated carcinoma and dedifferentiated carcinoma. Tumor-like lesions mentioned in WHO classification are polyp, metaplasia, Arias-Stella reaction, and lymphoma-like lesion. 7 The high resolution images obtained with TVS enable the detection of endometrial abnormalities ranging from simple increased endometrial thickness measurements to sophisticated morphologic evaluation of complex endometrial architecture. 8 The most widely used technique for obtaining a sample of endometrium is the curettage and 80% of all curettage procedures performed for postmenopausal bleeding result in benign diagnoses. 9,10 So, the use of TVS has been well established to avoid unnecessary curettage with multiple articles published in the literature. This study was an attempt to evaluate the role of TVS in diagnosing endometrial pathologies.

MATERIALS AND METHODS
359 women presenting with history of at least three months amenorrhea were included in this study after written consent. Transvaginal ultrasonography was performed in all cases with measurement of endometrial thickness and uterine size. Any other abnormalities like fibroid or parauterine cyst were also noted. Endometrial biopsies were taken in 69 cases (19.2%) only. Statistical analysis was done using SPSS version 20.

RESULTS
A total of 359 postmenopausal women were undergone TVS. The mean and median age of patients was 55 years and 53 years respectively with the age range of 42 years to 81 years. The maximum numbers of patients were in age group of 50-59 years (79.6%). 284 out of 359 patients visited for one or more complaints and 75 for routine check-up without any clinical symptoms. Abdominal pain is commonest symptoms followed by backache (Table 1). There was history of oral contraceptives intake in 15 patients and 95 patients were hypertensive.
In postmenopausal women, the normal length of uterus is usually between 4-6 cm. 1 In this study, 6 cm was taken as cut-off value. 3 out of 69 cases with histopathological diagnosis have normal sized uterus, while 66 cases had bulky (>6 cm) uterus ( Table 2).
The endometrial thickness measured by TVS is tabulated in table 3&4. Fifty-eight out of 69 cases showed more than 5 mm thick endometrium and the endometrium is abnormal in 31 cases. Histopathological examination was done in 69 cases only. The endometrial thickness of 5 mm was taken as cut-off value for discriminating normal and abnormal endometrium. 1 The sensitivity, specificity, positive predictive value and negative predictive value of TVS to detect abnormal endometrium are 91.2%, 22.9%, 53.4% and 72.7% respectively. In this study, there was single case of endometrial carcinoma having endometrial thickness of 20 mm. The sensitivity, specificity, positive predictive value and negative predictive value of TVS to detect endometrial hyperplasia and carcinoma are 100%, 17.5%, 10.3% and 100% respectively.         hyperplasia/carcinoma using endometrial thickness. 52 cases of non-carcinoma/non-hyperplasia had less than 5 mm of endometrial thickness and all 6 cases of endometrial carcinoma/hyperplasia had more than 5 mm of endometrial thickness. Thus endometrial carcinoma/hyperplasia can be excluded using endometrial thickness measured by TVS. However, TVS cannot differentiate endometrial hyperplasia/ carcinoma from non-hyperplasia/non-carcinoma when endometrial thickness is more than 5 mm. In addition, TVS revealed uterine leiomyoma in 65 cases and parauterine cyst in 15 cases.

DISCUSSION
The use of transvaginal sonography in the measurement of endometrial thickness in postmenopausal women with bleeding has been well established, with multiple articles in the literature. Our patients presented with per vaginal bleeding, discharge, abdominal pain, backache, and vulval itching, and uterine prolapse with abdominal pain being the commonest symptom. However, per vaginal bleeding is the commonest symptoms in some studies. 11,12 Several authors have attempted to define an endometrial thickness cut-off value below which no pathology is found, in the hopes of using this measurement as a screening tool in post-menopausal women with abnormal uterine bleeding. [13][14][15] In these studies, the mean endometrial thickness for patients with hyperplasia or carcinoma was greater than for those without pathology. Granberg S et al. recommended 5 mm cut-off limit of endometrial thickness for endometrial abnormality. 16 We have used 5 mm as cut-off value to discriminate normal from abnormal endometrium or hyperplasia/carcinoma from non-hyperplasia / noncarcinoma group. TVS is equally useful to determine the size of uterus. In this study, the cut-off value of uterine size was 6 cm to predict normal and abnormal endometrium. None of the women with less than 6 cm uterus had abnormal endometrium. 84.1% post-menopausal women with abnormal endometrium had more than 6 cm uterus. So, the measurement of uterine size by TVS may also aid in discriminating normal and abnormal endometrium.
Thus, postmenopausal women with less than 6 cm uterus and less than 5 mm thick endometrium do not need any invasive surgical procedures like curettage as there is no or little possibility to have abnormal endometrium.

CONCLUSIONS
Transvaginal sonographic evaluation of endometrial thickness and uterine size is a reliable method of screening post-menopausal women. It is useful for exclusion of endometrial pathology and 5 mm endometrial thickness threshold used conventionally helps to avoid unnecessary invasive surgical procedures.