Membrane-based, dry-reagent prothrombin time tests

OBJECTIVE: The study was designed to evaluate the effects of a new low-dose monophasic combined oral contraceptive (100 micrograms levonorgestrel/20 micrograms ethinylestradiol) on ovarian activity. METHOD: This was an open-label study in 15 healthy female volunteers. After an ovulatory pretreatment cycle, subjects were treated for three consecutive cycles. RESULTS: Out of 15 healthy females with an ovulatory pretreatment cycle, 13 completed the study and two dropped out. In ten females, various degrees of ovarian activity were characterized, mainly in the second and third treatment cycle. In eight cases follicle-like structures either persisted or developed throughout the pill-free interval, growing up to luteinized unruptured follicles or cyst-like structures that reduced their size or disappeared in the following treatment cycle. CONCLUSION: Ovarian follicular activity was significantly suppressed during treatment with levonorgestrel 100 micrograms/ethinylestradiol 20 micrograms. Similarly, endogenous ovarian steroid production was almost uniformly decreased. A 'dissociation' of ovarian and endometrial development was also seen during this therapy.