Enlarged follicles in women using oral contraceptives

Ultrasound examination of the ovaries was performed in the first and/or second half of three consecutive cycles in 3 groups of women; Group T who had been using a levonorgestrel triphasic oral contraceptive for at least 6 months, Group P who had been using a progestogen-only pill for at least 6 months, and Group C, a control group. Any follicles greater than 10 mm in diameter and any cysts were measured. Fifty-three scans were performed in Group T, 45 in Group P and 31 in Group C. Only 4 follicles were detected in 17 women in Group T compared to 10 follicles in 15 women in Group P and 7 follicles in the women in Group C; all follicles were 25 mm or less in diameter except for 3 follicles in 2 women. The differences between the groups were not statistically significant. Four enlarged follicles were detected in 3 women during 53 scans in Group T, 15 in 8 women (45 scans) in Group P, and only 1 in 31 scans in Group C. Based upon the proportions of scans with enlarged follicles, the difference between Groups T and P was statistically significant, indicating that the incidence of enlarged follicles was lower in women using a combined oral contraceptive than in those using a progestogen-only pill. Furthermore, the study shows that any enlarged follicles which occurred were transient.