A 36-year-old woman comes to the physician to discuss contraceptive options. She is currently sexually active with one male partner, and they have not been using any contraception. She has no significant past medical history and takes no medications. She has smoked one pack of cigarettes daily for 15 years. She is allergic to latex and copper. A urine pregnancy test is negative. Which of the following contraceptive methods is contraindicated in this patient?

Combined oral contraceptive pill

A 19-year-old woman comes to the physician because of recent weight gain. She started a combined oral contraceptive for dysmenorrhea and acne six months ago. She has been taking the medication consistently and experiences withdrawal bleeding on the 4th week of each pill pack. Her acne and dysmenorrhea have improved significantly. The patient increased her daily exercise regimen to 60 minutes of running and weight training three months ago. She started college six months ago. She has not had any changes in her sleep or energy levels. Her height is 162 cm and she weighs 62 kg; six months ago she weighed 55 kg. Examination shows clear skin and no other abnormalities. A urine pregnancy test is negative. Which of the following is the most appropriate next step in management?

Measure serum testosterone concentration

Perform a low-dose dexamethasone suppression test

Switch contraceptive to a non-hormonal contraceptive method

A 22-year-old female presents to her PCP after having unprotected sex with her boyfriend 2 days ago. She has been monogamous with her boyfriend but is very concerned about pregnancy. The patient requests emergency contraception to decrease her likelihood of getting pregnant. A blood hCG test returns negative. The PCP prescribes the patient ethinyl estradiol 100 mcg and levonorgestrel 0.5 mg to be taken 12 hours apart. What is the most likely mechanism of action for this combined prescription?

Inhibition or delayed ovulation

Interference of corpus luteum function

Thickening of cervical mucus with sperm trapping

Tubal constriction inhibiting sperm transportation

Alteration of the endometrium impairing implantation of the fertilized egg

A 21-year-old G2P1 woman presents to the clinic and is curious about contraception immediately after her baby is born. She is anxious about taking care of one child and does not believe that she can handle the responsibility of caring for another. She has no other questions or complaints today. Her past medical history consists of generalized anxiety disorder, antithrombin deficiency, and chronic deep vein thrombosis. She has been hospitalized for acute on chronic deep vein thrombosis. Her only medication is buspirone. Her blood pressure is 119/78 mm Hg and the heart rate is 78/min. BMI of the patient is 32 kg/m2. On physical examination, her fundal height is 21 cm from pubic symphysis. No ovarian masses are palpated during the bimanual examination. Ultrasound exhibits a monoamniotic, monochorionic fetus. Which of the following forms of contraception would be the most detrimental given her risk factors?

Depot medroxyprogesterone acetate

Hormonal contraceptives for USMLE Step 2 CK: High-Yield Pharmacology Lessons

Mechanism of Action - Halting the Cycle

Primary Driver (Progestin): Halts the cycle through multiple synergistic actions.
- Inhibits Ovulation: Suppresses the mid-cycle LH surge by acting on the hypothalamus (↓ GnRH pulsatility) and pituitary.
- Thickens Cervical Mucus: Creates a physical barrier, blocking sperm penetration.
- Thins Endometrium: Atrophic endometrium is unreceptive to blastocyst implantation.
- Slows Tubal Motility: Impairs transport of both sperm and egg.
Synergist (Estrogen): Primarily supports the progestin component in combined hormonal contraceptives (COCs).
- Suppresses FSH: Prevents the selection and development of a dominant follicle.
- Stabilizes Endometrium: Provides cycle control and minimizes breakthrough bleeding.

⭐ Progestin alone is sufficient for contraception and is the key component. Estrogen is added mainly to regulate bleeding (endometrial stability) and potentiate the suppression of follicular development.

Hypothalamic-Pituitary-Ovarian Axis

The Hormone Players - Estrogens vs. Progestins

Estrogens	Progestins
Primary Role: Suppress FSH & stabilize endometrium	Primary Role: Suppress LH surge (inhibits ovulation)
* Examples: Ethinyl estradiol, Mestranol	* Examples: Levonorgestrel, Norgestimate, Drospirenone
* Mechanism: Potentiates progestin effects. Prevents follicular development. Reduces breakthrough bleeding.	* Mechanism: Thicken cervical mucus (blocks sperm). Slow fallopian tube motility. Induce endometrial atrophy.
* Side Effects: Breast tenderness, nausea, VTE, cholestasis.	* Side Effects: Mood swings, acne, androgenic effects (varies by type).

Delivery Systems - Pills, Patches, & Pokes

Oral Contraceptive Pills (OCPs): Daily dosing. Requires high user adherence.
- Combined (Estrogen + Progestin): Most common form.
- Progestin-only ("Minipill"): For patients with contraindications to estrogen (e.g., migraine with aura, smokers >35).
Long-Acting Reversible Contraceptives (LARCs): Highest efficacy.
- Implant (e.g., Nexplanon): Subdermal, progestin-only. Lasts 3 years.
- IUD (e.g., Mirena): Intrauterine, progestin-only. Lasts 3-8 years.
Other Methods:
- Patch: Weekly application.
- Vaginal Ring: Monthly insertion.
- Injection (Depo-Provera): Every 3 months. ⚠️ Can cause bone density loss.

⭐ Exam Favorite: The transdermal contraceptive patch has a higher systemic estrogen exposure and is associated with an increased risk of venous thromboembolism (VTE) compared to most combined OCPs.

Adverse Effects & Rules - Risks & Contraindications

Common AEs: Breakthrough bleeding, nausea, breast tenderness, mood changes.
Serious AEs (Estrogen): ↑ risk of Venous Thromboembolism (VTE), Pulmonary Embolism (PE), MI, and stroke.
- 📌 ACHES mnemonic for serious clot signs: Abdominal pain, Chest pain, Headaches (severe), Eye problems (vision loss), Severe leg pain.

⭐ Progestin-only pills are preferred for patients with contraindications to estrogen, such as smokers >35 years, or those with a history of migraine with aura or VTE.

Medical Eligibility for Contraception: Contraindications

High‑Yield Points - ⚡ Biggest Takeaways

Combined OCPs (estrogen + progestin) primarily inhibit ovulation by suppressing GnRH, FSH, and LH.

Progestin-only pills mainly thicken cervical mucus, preventing sperm entry, and are safe during lactation.

The estrogen component is responsible for the increased risk of venous thromboembolism (VTE).

Key contraindications: history of VTE, estrogen-dependent tumors, severe liver disease, and smokers >35 years old.

Copper IUDs are non-hormonal; they create a local inflammatory reaction toxic to sperm.

Levonorgestrel IUDs release progestin locally, thickening cervical mucus and thinning the endometrium.

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