Transvaginal ultrasonographic findings in the uterus and the endometrium: Low prevalence of leiomyoma in a random sample of women age 25–40 years

Background. In articles and textbooks the prevalence of uterine leiomyomas is said to be 20–25% in women over the age of 30. The aim of this study was to investigate the rate of uterine leiomyoma, the thickness and the texture of the endometrium, and the size of the uterus in a random sample of asymptomatic women 25–40 years old. Methods. A random sample of women 25–40 years old was offered a transvaginal ultrasonographic examination and 335 (72%) accepted the invitation. Results. In 18 women uterine leiomyomas were detected, i.e. 5.4% (95% CI 3.0–7.8%). The prevalence of leiomyomas increased with age, being 3.3% (95% CI 0.7–6.0%) in the 25–32 years age group and 7.8% (95% CI 3.6–12.0%) in the 33–40 age group. The size of the uterus correlated to parity, age and height. In women on combined oral contraceptives the size of the uterus was smaller than in women with natural cycles. The size of the uterus did not correlate to body mass index, cycle day or smoking habits. The endometrium increased in thickness and had in most cases a triple line appearance during the proliferative phase until day 15, whereafter it was unchanged in thickness throughout the secretory phase and hyperechogenic in appearance. Conclusions. This study confirms earlier studies on the endometrium based on selected populations. The size of the uterus increased with parity, age and height, and was smaller in combined oral contraceptive users. The prevalence figures for uterine leiomyomas in textbooks are not confirmed.