RESUMEN
PIP: Microval, a low dose progestin oral contraceptive (OC) containing .03 mg levonorgestrel, provides contraception through 3 mechanisms: rendering the cervical mucus impermeable to sperm, slowing the descent of the egg through the fallopian tube, and causing endometrial atrophy unfavorable to nidation. The Pearl index is about 1%. Formal contraindications to Microval include suspicion of pregnancy, recent history of hepatitis or hepatic insufficiency, and breast or uterine cancer, while relative contraindications include ovarian dystrophy, mastopathy, and history of extrauterine pregnancy, jaundice, or pruritus of pregnancy. As with any other OC, a complete physical examination should be done before prescription to rule out contraindications, and follow-up examinations should be given twice yearly. Irregular cycles, spotting, amenorrhea, edema, and breast discomfort are not unusual at the beginning of treatment. Rifampicine, barbiturates, phenylbutazone, and the hydantoin group of drugs render Microval ineffective. The pill should be taken every day without exception at the same hour, and it is advisable to use another method of contraception during the 1st month of Microval use. A single pill taken 12 hours late can bring a risk of pregnancy. Low dose progestins are of interest for patients with contraindications to synthetic estrogens who desire an OC, but they can induce a relative hyperestrogenism with ovarian dystrophy and other symptoms, and they can cause menstrual irregularity.^ieng