Contraception Flashcards
When does pregnancy begin?
- Pregnancy begins at IMPLANTATION of zygote to endometrial wall (NOT FERTILIZATION OF OOCYTE)
- ## Demonstrated by +hCG
Steps needed for pregnancy (potential mechanisms for preventing pregnancy)
- Production & Maturation of gametes: (Prevent by blocking FSH)
- Ovulation of oocyte & passage through Fallopian tubes: (block LH surge, or cut Fallopian tubes)
- Ejaculation of Sperm: (Vasectomy: cutting Vasa Deferentia)
- Fertilization: (Barrier methods)
- Implantation: (Alter uterine lining)
Window of Peak Fertility
- Days 10 to 17 (assuming ovulation is on day 14)
- Luteal phase is consistently 14 days
- Peak fertility window is determined by Follicular phase
Surgical Methods of Contraception
- NOT REVERSIBLE
- Tubal ligation: cut & cauterize Fallopian tubes
- Transcervical sterilization: Insertion of Fallopian tube coils to scar uterine lining
- Vasectomy: Cut & cauterize Vasa Differentia
Immediately Reversible methods of contraception
- Copper IUD
- Barrier Methods
- Natural family planning
- Combination E/P: may take 3-6 months to reverse
- Longer acting hormonal methods: up to 6 months to reverse
Contraception methods with <10% Failure Rate
- E/P pill, patch, ring
- DMPA
Contraception methods with <1% Failure Rate
- Copper IUD
- LNG-IUD
- Progesterone implant
- Tubal Ligation
- Vasectomy
- Transcervical sterilization
Short-acting vs. Long-acting
- How often you have to renew the method
Short-acting: up to every 3 months
Long-acting: once every 3 months or longer
Progesterone Only: Delivery Methods
- Progesterone Pill (“Mini” Pills): Least reliable; indicated for breastfeeding women for which estrogen is poorly tolerated/contraindicated); requires taking at same time everyday
- Depot Medroxyprogesterone Acetate Injection (DMPA): < 1% failure
- LNG-IUD: <1% failure; best compliance
Progestins
- Progesterone
- Norethindrone
- (Levo) Norgestrel (LNG)
Progesterone
- Natural progestin
- precursor to estrogen
- produced in ovaries by corpus luteum; production stimulated by LH surge, or by hCG during pregnancy
ANDROGENIC: main reason for side effects
Estranes: 19-Nortestosterone-like compounds
- Synthetic progestin (2nd generation)
- Contains C17 ethinyl group: DECREASES HEPATIC METABOLISM; INCREASES HALF-LIFE
- still has androgenic side effect activity
Gonanes: 19-Nor 13-ethyl compounds
- 3rd generation synthetics
- DECREASED ANDROGENIC ACTIVITY
- ALSO Contains C17 ethinyl group: DECREASES HEPATIC METABOLISM; INCREASES HALF-LIFE
Mechanism of Progestins:
- secondary benefits
Activation of Progesterone Receptors (PRs)
- PR-A: Inhibits
- PR-B: Stimulatory properties
Physiologic doses (during menses):
- Supports Luteal phase, generating secretory endometrium
- Elevates temp at onset of ovulation
- suppresses mentruation/uterine contractions during pregnancy
- Decreases frequency of GnRH pulses –> results in negative feedback of LH production
Pharmacological doses (contraceptive):
- Endometrial regression: impairs implantation
- Creates thick cervical mucus, decreasing sperm penetration
- Prevents ovulation by decreasing frequency of GnRH pulses
Secondary benefits:
- Lighten or completely stop menses (but 1/3 have irregular spotting)
- LNG-IUD is FDA approved to treat MENORRHAGIA (very heavy menses)
Contraindications of Progestins
- Pregnancy
- History of Breast Cancer
- Undiagnosed Vaginal Bleeding
- Active Thromboembolic Disease
- Abnormal Liver Function
Toxicities of Progestin-Only Preps
- Irregular mentrual bleeding
- Increased BP: use with caution in HTN patient
- Raise LDL, but decrease HDL
- For long term therapy: delayed return to ovulatory function
- Androgenic effects: Acne, Hirsutism
- Weight gain: 15-20 lbs/year
- Increased risk of breast cancer when used with estrogen for Hormonal Replacement Therapy
Estrogens
- Estradiol: really short half life (minutes)
- Ethinyl Estradiol: No first pass effects, thereby having longer half life (13-27 hours)
Indications:
- Estrogen deficiency: Hormone Replacement Therapy
- Prevents/retards Osteporosis
- Contraception
- Hirsutism: suppresses ovarian androgen production
- Amenorrhea
- Dysfunctional uterine bleeding
- Dysmenorrhea
- Before ovulation: produced in FOLLICLE by theca & granulosa cells
- After ovulation: produced in CORPUS LUTEUM by Luteinized granulosa & theca cells
Pharmacokinetics of Estrogens
- Rapid biotransformation, half-life only lasting minutes (Ethinyl Estradiol avoids first pass effect, lengthening half life to 13-27 hours)
- undergoes ENTEROHEPATIC CYCLING to maintain levels of estrogen
- Contraindicated with Antibiotics: Antibiotics decrease microflora, reducing enterohepatic cycling
- Rifampin Abx (induces hepatic enzymes): potential chemical/drug interactions that induce clearance of estrogen
Effects of Estrogen
- Decreases rate of bone resorption by increasing osteoclast apoptosis and decreasing PTH –> reduces osteoporosis
- Net favorable effects on plasma lipids
- Decreases bile acid secretion –> increases risk for gallstones
- Induces Blood Coagulation: increased risk of clot formation
- Increases progesterone receptor synthesis: synergistic effect
Combo E/P Delivery Methods
- Pill: Monophasic (fixed doses of E/P); Multiphasic (Dose of Progesterone varies throughout); Continuous use (Quarterly menses)
- Patch: replace weekly
- Nuvaring: Inserted in vagina for 3 weeks
Combo E/P Mech of action
Progesterone:
- decreases GnRH pulses –> suppresses LH
- Thick cervical mucus: inhibits travel of sperm
- Atrophic endometrium
Estrogen:
- Inhibits FSH secretion
- Altered transport of Fallopian tube
Secondary Benefits:
- improved acne
- regulation/control of menstrual cycle
- lighter & shorter periods: prevent anemia
- Improved cramps: dysmenorrhea
- Protection against osteopenia
- decreased risk of ovarian and endometrial cancer
Combo E/P Contraindications
- Cardiovascular disease: Stroke, HTN
- Thromboembolic disease/hypercoag
- Abnormal liver function
- History of breast cancer in that patient (family history of breast cancer is NOT a contraindication)
- Smoker > 35 yo
- Migraine with neurological aura
- Vaginal bleeding
- Pregnancy or breast feeding
- Fibroids, Diabetes, Severe Headaches
Combo E/P Major Toxicities
- Thromboembolism/MI: esp in older patients or smokers
- Gallbladder disease: b/c decreased secretion of bile acids
- Cause Migraines w/o aura: due to incresed risk of stroke
- No increased risk of breast cancer for E/P contraception use (risk is increased only at doses for HRT) (Estrogen may be protective against ovarian/endometrium cancer)
- HTN
- Delayed Return to Fertility
Barrier Contraceptives
Methods: Prevent fertilization by stopping sperm from entering uterus
- Male condom: physical barrier
- Female condom: may be inserted up to 8 hours before intercourse
- Diaphragm: fits against vaginal wall near base of cervix; is a chemical barrier (used with spermicide)
- Cervical cap (physical barrier)/sponge (chemical barrier): fits snugly over cervix; high failure rate
- Spermicide
Effectiveness: 15-20% failure rate/year
Convenience: Short acting
Contraindications: allergy to latex or spermicide
Side effects: diaphragm may increase risk of UTI
Secondary benefits:
- STI protection
- male condom: Prevent premature ejaculation
- female condom: clitoral stimulation from external ring