Ultrasonographic features of the endometrium and the ovaries in women on etonogestrel implant.

OBJECTIVE: To evaluate the ultrasound features of the endometrium and ovaries in women on etonogestrel implant, and to correlate these features with the bleeding pattern. METHODS: Observational study including 188 consecutive women presenting for follow-up transvaginal ultrasound examination after insertion of an etonogestrel implant contraceptive device. Thirty women had more than one follow-up examination. The bleeding pattern was considered abnormal if, in the last 3 months, there were more than five episodes of vaginal bleeding, or there was prolonged bleeding exceeding 14 consecutive days. RESULTS: At first follow-up examination, the mean age was 29.7 years and 47% of women had an abnormal bleeding pattern. Most bleeding episodes were of less intensity than menses. The mean endometrial thickness (ET) on ultrasound was 2.9 mm (standard deviation, 2.0). Ovarian follicle growth exceeding 5 mm was observed in 60% of the cases. Ovulation was demonstrated in one woman. Univariate analysis showed a positive association (P < 0.01) between ET, bleeding pattern, and bleeding intensity. Follicle growth was positively associated (P < 0.01) with ET, bleeding pattern, and interval between insertion and examination. Multivariate analysis showed that the ET was on average 1.25 mm greater in women with abnormal bleeding (P = 0.0001). The odds of finding follicle growth were 2.8 times higher (95% confidence interval, 1.2-6.2) in women presenting with a three-layer type of endometrial morphology. There was no association between the other patients' characteristics and the bleeding pattern. CONCLUSIONS: Abnormal uterine bleeding in women on etonogestrel implant was associated with follicle growth and a thicker, three-layer type of endometrium, suggesting incomplete ovarian inhibition and estrogen stimulation of the endometrium.