Objectives

To evaluate the efficacy and acceptance of transrectal ultrasound scan (TRS) in assessing the endometrium in postmenopausal women with an axial uterus.

Methods

This was a prospective cross-sectional study, between Oct 2015 and October 2018, in which consecutive postmenopausal women with an axial uterus on transvaginal ultrasound scan (TVS) were included. Women with a known diagnosis of gynaecological malignancy were excluded. TRS was offered immediately after the initial TVS with no prior bowel preparation. A single operator subjectively determined whether the endometrium was satisfactorily visualised or not. In women with postmenopausal bleeding (PMB), the endometrium was measured and categorized as atrophic, uniformly thickened, benign endometrial polyp or endometrial cancer, based on subjective pattern recognition. Subsequently, all women with PMB and a non-atrophic endometrium underwent either an outpatient endometrial biopsy or hysteroscopy.

Results

Among 1553 women who underwent a TVS, 103 (6.6%) had an axial uterus, of which 76/103 (74%) presented with PMB. TRS was accepted by 66/103 (64%) women with an axial uterus. TRS satisfactorily assessed a significantly higher proportion of endometria compared to TVS, 60/66 (91%) vs 41/66 (62%), respectively (X2=14.1, p<0.001). In 50 women with PMB and an axial uterus who underwent both TVS and TRS, TVS failed to visualise the endometrium satisfactorily in 15/50 (30%) women, whilst TRS provided satisfactory images in all cases. Among the 35/50 women with PMB and a satisfactory endometrial assessment on TVS and TRS, the measurements of the endometrial thickness on TRS were significantly lower compared to TVS [median difference -1.2mm (IQR: -3 to -0.40)]. The overall agreement of TVS and TRS on the presence or absence of endometrial cancer using subjective pattern recognition was 30/35 (86%, 95% C.I. 74-97). However, while all seven cases of histologically confirmed endometrial cancer were correctly diagnosed on TRS, four of them were misdiagnosed on TVS as benign polyps or uniformly thickened endometrium.

Conclusions

Transrectal ultrasound scan is an acceptable and effective way to assess the endometrium in postmenopausal women with an axial uterus. It is associated with a higher proportion of satisfactory endometrial assessments and fewer misdiagnoses of endometrial cancer by subjective pattern recognition when compared to TVS.

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