In accordance with the WHO Medical Eligibility Criteria for Contraceptive Methods, laboratory tests before prescribing COCs are not considered mandatory. But the doctor always collects a detailed history, and to clarify it (if there are problems), he can prescribe tests.
Combined oral contraceptives are rightfully considered the most reliable – their effectiveness exceeds 99%. The mechanism of contraceptive action of COCs is to suppress ovulation and thicken mucus in the cervix. As a result, the egg does not leave the follicle, and the sperm cannot break into the uterine cavity.
But for taking hormonal drugs, including hormonal contraceptives, there really is a fairly wide group of contraindications, including varicose veins, thrombophilia, liver and cardiovascular system diseases, and oncological diseases. But at the same time, many contraceptives have an additional therapeutic effect and can save you from PMS, painful or too heavy periods, acne and antennae. The doctor takes into account the ratio of different hormones in tablets, correlates them with your diagnosis and selects the optimal one. That is why you can take COCs only after consulting a gynecologist.