ABSTRACT

The prevalence of adnexal pathology in the first trimester has been reported as varying from 0.2% to 5.4%.1-4 In a recent cross-sectional study, the prevalence of ovarian cysts at various stages of pregnancy was assessed, i.e. in the first, second and third trimesters. Only 1.2% (79/6636) of the total number of women in this study had an ovarian cyst with a maximum diameter of greater than 30 mm.3 This figure was significantly lower than in a more recent longitudinal study in which the prevalence of ovarian cysts of ≥25 mm in the first trimester was 5.4% (161/3000).4 This difference in prevalence most likely reflects the different cut-off values used as inclusion criteria in these studies and the timing of the scans. In the paper by Condous et al. transvaginal scans (TVS) were performed in the first trimester, when one would expect the presence of more physiological ovarian cysts, such as functional corpora lutea. After 16 weeks’ gestation the prevalence of ovarian cysts is reported to be between 0.5% and 3.0%.2,3 In our longitudinal study, the prevalence of ovarian cysts beyond 16 weeks’ gestation was 0.9%, which is in keeping with these previous reports. In short, as the pregnancy advances, the prevalence of ovarian cysts falls.