Gynecology Topic 13. Barrier and chemical contraceptives. Natural contraceptive methods

I. Barrier Contraceptives

General Features

• Barrier contraceptives: physically prevent sperm from entering the cervix/uterine cavity.
• Effectiveness: user-dependent → higher failure rate than hormonal contraception/IUDs.
• Main advantage of condoms: protection against sexually transmitted infections (STIs).

Male and Female Condoms

• Male condom: covers penis → semen retained → sperm cannot enter vagina.
• Female condom: vaginal pouch with rings → covers vaginal wall and part of vulva/perineum.
• Advantages: STI protection, cheap, reversible, no systemic side effects.
• Disadvantages: user-dependent, breakage/slippage/displacement, irritation or latex allergy possible.

Diaphragm and Cervical Cap

• Diaphragm: dome-shaped cup covering cervix and upper vagina.
• Cervical cap: smaller cap fitted over cervix.
• Usually used with spermicide → higher effectiveness than barrier alone.
• Timing: must remain in place for at least 6 h after intercourse.
• Disadvantages: less effective/user-dependent, fitting/use technique needed, no reliable STI protection, increased UTI risk.

II. Chemical Contraceptives

Spermicides

• Spermicides: chemical agents that damage sperm cell membranes → sperm immobilization/death → fertilization prevented.
• Common agent: nonoxynol-9.
• Forms: creams, gels, foams, films, suppositories.
• Use: insert into vagina before intercourse; many preparations need about 10-30 min.
• Repeat application: needed before each act of intercourse.
• More effective with barrier methods; spermicide alone has high failure rate.
• Disadvantages: vaginal/vulvar irritation, burning/allergy; frequent nonoxynol-9 irritation may increase STI/HIV susceptibility.

III. Natural / Physiologic Methods

Periodic Abstinence / Fertility Awareness

• Principle: avoid intercourse or use barrier method during fertile window shortly before and after ovulation.
• Basal body temperature: slight temperature rise after ovulation → confirms ovulation retrospectively, not ideal for prediction.
• Cervical mucus: estrogenic mucus becomes clear, stretchy and slippery near ovulation; dry/thick mucus is less fertile.
• Ovulatory symptoms: mittelschmerz, breast tenderness or other cyclic symptoms may help but are unreliable alone.
• Disadvantages: high user-dependence, requires motivation and regular cycles, poor choice if pregnancy must be strongly avoided.

Other Natural Methods

• Standard days/calendar method: estimate fertile window from cycle length; only useful with regular cycles.
• Coitus interruptus: withdrawal before ejaculation; high failure rate and no STI protection.

Lactational Amenorrhea Method

• Mechanism: frequent suckling → ↑ prolactin + hypothalamic suppression → ↓ GnRH pulsatility → ovulation inhibition.
• Effective only if all criteria are fulfilled:

• Infant age < 6 months.
• Mother remains amenorrheic.
• Exclusive or near-exclusive breastfeeding.
• Frequent breastfeeding, including night feeds.

• Limitation: ovulation may return before first postpartum menstruation → pregnancy can occur before visible menses.

IV. Permanent / Operative Methods

General Counseling

• Sterilization: highly effective but should be considered permanent.
• Careful counseling and informed consent are essential.
• Failure is rare but possible; pregnancy after tubal sterilization has increased ectopic pregnancy risk.

Tubal Sterilization

• Mechanism: tubal occlusion/interruption → sperm and oocyte cannot meet.
• Approaches: laparoscopy, postpartum sterilization or during cesarean delivery.
• Complications: bleeding, infection, bowel/vascular injury, anesthesia risk, failure/ectopic pregnancy.

Vasectomy

• Mechanism: vas deferens is cut/occluded → sperm absent from ejaculate after clearance period.
• Important: sterility is delayed; use other contraception until semen analysis confirms azoospermia/sperm-free ejaculates.
• Complications: minor bleeding, hematoma, infection, chronic pain rarely; reversal is not guaranteed.