Efficacy of transrectal ultrasound in assessing endometrium of postmenopausal women with axial uterus

OBJECTIVE: To evaluate the acceptance and efficacy of transrectal ultrasound (TRS) in assessing the endometrium in postmenopausal women with an axial uterus. METHODS: This was a prospective cross-sectional study conducted between October 2015 and October 2018 of consecutive postmenopausal women with an axial uterus on transvaginal ultrasound (TVS). Women with a known diagnosis of gynecological malignancy were excluded. TRS was offered immediately after TVS without prior bowel preparation. A single operator determined subjectively whether the endometrium was visualized satisfactorily on TVS and TRS. In women with postmenopausal bleeding (PMB), endometrial thickness (ET) was measured and endometrial morphology was categorized as atrophic, uniformly thickened, benign endometrial polyp or endometrial cancer, based on subjective pattern recognition. All women with PMB and a non-atrophic endometrium underwent outpatient endometrial biopsy, hysteroscopy or hysterectomy. The success rate of TRS in assessing satisfactorily the endometrium was compared with that of TVS. In patients with PMB, ET measurements and subjective diagnosis of endometrial cancer on TVS vs TRS were compared. In 50 women with PMB and an axial uterus who underwent both TVS and TRS, TVS failed to visualize the endometrium satisfactorily in 15 (30.0%) women, whilst TRS provided satisfactory images in all cases. Among the 35 women with PMB and a satisfactory endometrial assessment on TVS and TRS, measurements of ET on TRS were significantly lower compared to those on TVS (median difference, -1.2 (interquartile range, -3.0 to -0.4) mm). The overall agreement of TVS and TRS on the presence or absence of endometrial cancer using subjective pattern recognition was 30/35 (85.7%; 95% CI, 74.1-97.3%). While all seven cases of histologically confirmed endometrial cancer were diagnosed correctly on TRS, four were misdiagnosed on TVS as benign polyps or uniformly thickened endometrium. CONCLUSIONS: TRS is an acceptable and effective way to assess the endometrium in postmenopausal women with an axial uterus. Among women presenting additionally with PMB, TRS is associated with a higher proportion of satisfactory endometrial assessments and fewer misdiagnoses of endometrial cancer by subjective pattern recognition compared with TVS.