Sonographic endometrial thickness: a useful test to predict atrophy in patients with postmenopausal bleeding. An Italian multicenter study.

Eighteen centers took part in this prospective study into which 930 eligible patients were recruited. The selection criteria for admission were atypical bleeding after at least 6 months of postmenopausal amenorrhea, and absence of hormonal therapies for at least 6 months. The sonographic measurement of the maximum bi-endometrial thickness was made in a longitudinal plane. Sonographic measurements were always performed within 3 days prior to histological evaluation. In these patients the mean number of years from menopause (25-75th centile) was 6 (range 2-16). The prevalence of endometrial carcinoma was 11.5% and the prevalence of atrophy was 49.2%. The area under the receiver operator characteristic curves generated by sonographic thickness measurements reached the level of 85%, both for cancer and atrophy. The likelihood ratio for cancer, yielded by an endometrial thickness of < or = 4.0 mm, was 0.05, and for atrophy it was 7.1. This cut-off of > 4.0 mm yielded a sensitivity for the detection of cancer of 98% and a negative predictive value of 99%. The overall sensitivity and positive predictive value for atrophy achieved by this cut-off were 57.2% and 87.3%, respectively. A multivariate logistic model showed that age and body mass index were independent variables associated with a significantly higher risk of endometrial cancer. The post-test probabilities for cancer and atrophy were recalculated on the basis of the integration of age, body mass index and endometrial thickness. The estimated reduction of invasive procedures on the basis of this integration was 31%. Transvaginal sonographic measurement of endometrial thickness, integrated with individual risk factors, can help in the management of postmenopausal patients with atypical bleeding, with regard to either the need for histological evaluation in high risk cases, or the choice of possible expectant management. We have shown that an endometrial thickness of < or = 4.0 mm safely predicts endometrial atrophy and justifies expectant management when the patient understands the need for proper follow up. This could be achieved with a reduction in the use of invasive procedures without unwanted delay in cancer diagnosis.