Contraceptive method mechanisms, effectiveness, and contraindications tested on USMLE Step 1.
35 cards · basic cards · AI-written, checked twice. Edit anything.
- By what mechanism do combined oral contraceptives (estrogen + progestin) prevent pregnancy?
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They suppress GnRH pulsatility, lowering FSH and LH so the LH surge and ovulation never occur.- Which hormone in combined OCPs is mainly responsible for thickening cervical mucus?
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The progestin component.- What is the perfect-use failure rate of combined oral contraceptives?
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About 0.3% per year.- What is the typical-use failure rate of combined oral contraceptives?
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About 7% per year.- What is the mechanism of action of the copper IUD?
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Copper ions trigger a sterile inflammatory reaction that is toxic to sperm and ova, with no hormonal effect.- How long is the copper IUD effective for pregnancy prevention?
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Up to 10 years.- What is the mechanism of action of the levonorgestrel-releasing IUD?
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It thickens cervical mucus and thins the endometrial lining, and can also suppress ovulation in some cycles.- Which category of reversible contraception has the lowest typical-use failure rate?
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Long-acting reversible contraception (LARC): IUDs and the subdermal implant.- What is the mechanism of action of depot medroxyprogesterone acetate (DMPA)?
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It suppresses the LH surge, inhibiting ovulation.- What is a major long-term side effect of DMPA (Depo-Provera)?
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Decreased bone mineral density.- How often must DMPA be injected to maintain contraceptive effectiveness?
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Every 3 months (about every 12 weeks).- How long does a single etonogestrel subdermal implant (Nexplanon) provide contraception?
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Up to 3 years.- Why are estrogen-containing contraceptives contraindicated in smokers over age 35?
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Increased risk of venous thromboembolism, myocardial infarction, and stroke.- Why is migraine with aura an absolute contraindication to estrogen-containing contraceptives?
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It increases the risk of ischemic stroke.- Why is a history of venous thromboembolism a contraindication to estrogen-containing contraceptives?
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Estrogen increases clotting factors, raising the risk of recurrent VTE.
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