USMLE Guide: Contraception Methods

Introduction

Contraception methods are an essential aspect of reproductive health. This guide provides an overview of common contraception methods, their mechanisms of action, efficacy rates, and potential side effects. Understanding these methods is crucial for healthcare professionals to educate patients and assist them in choosing the most suitable contraception method.

Table of Contents

1. Barrier Methods
2. Hormonal Methods
3. Intrauterine Devices
4. Sterilization
5. Emergency Contraception

1. Barrier Methods

Barrier methods of contraception physically prevent sperm from reaching the egg. They include:

• Male Condoms: These are sheaths worn over the penis, collecting sperm and preventing their entry into the vagina. Condoms also reduce the risk of sexually transmitted infections (STIs).
• Female Condoms: These are polyurethane pouches that line the vagina and prevent sperm from reaching the cervix.
• Diaphragm: A dome-shaped silicone cup placed over the cervix, creating a barrier for sperm.

Efficacy: Barrier methods have varying efficacy rates, with male condoms being approximately 85% effective, while diaphragms and female condoms are approximately 80% effective.

Side Effects: Barrier methods have minimal side effects, but some individuals may experience latex allergies or irritation.

2. Hormonal Methods

Hormonal methods of contraception alter hormone levels to prevent ovulation and/or create an unfavorable environment for fertilization. They include:

• Combined Oral Contraceptives (COC): These contain synthetic estrogen and progestin, inhibiting ovulation and thickening cervical mucus. COCs are taken orally daily.
• Progestin-Only Pills (POP): These contain only progestin and primarily work by thickening cervical mucus, inhibiting sperm penetration.
• Injectable Contraceptives: These include depot medroxyprogesterone acetate (DMPA) injections, given every 12-13 weeks.
• Implants: Subdermal implants, such as etonogestrel implants, provide long-term contraception for up to three years.
• Transdermal Patches: These patches contain estrogen and progestin, releasing hormones through the skin and worn weekly.
• Vaginal Rings: These flexible rings are inserted into the vagina and release estrogen and progestin for three weeks.

Efficacy: Hormonal methods have high efficacy rates, ranging from 92-99%.

Side Effects: Potential side effects include breast tenderness, breakthrough bleeding, nausea, and mood changes. Some hormonal methods may increase the risk of thromboembolic events.

3. Intrauterine Devices (IUDs)

IUDs are small T-shaped devices placed inside the uterus. They work by altering the uterine environment, preventing fertilization and implantation. Two types of IUDs are available:

• Copper IUD: This non-hormonal IUD releases copper, which is toxic to sperm, reducing their motility and viability.
• Hormonal IUD: This IUD releases progestin, thickening cervical mucus and thinning the endometrium, preventing sperm penetration and implantation.

Efficacy: IUDs are highly effective, with a failure rate of less than 1%.

Side Effects: Common side effects include irregular bleeding, cramping, and expulsion of the device. Hormonal IUDs may cause hormonal side effects similar to other progestin-containing methods.

4. Sterilization

Sterilization methods provide permanent contraception and are typically considered irreversible. Two common approaches include:

• Tubal Ligation: This surgical procedure involves tying, cutting, or sealing the fallopian tubes, preventing sperm from reaching the eggs. It is performed in females.
• Vasectomy: This surgical procedure involves cutting or blocking the vas deferens, preventing sperm from entering the ejaculate. It is performed in males.

Efficacy: Sterilization methods are highly effective, with failure rates less than 1%.

Side Effects: Sterilization is a permanent method and should be approached with the understanding that it may not be reversible. Some individuals may experience post-surgical complications.

5. Emergency Contraception

Emergency contraception methods are used after unprotected intercourse or contraceptive failure. Two options are available:

• Copper IUD: When inserted within 5 days of unprotected intercourse, the copper IUD can prevent pregnancy.
• Emergency Contraceptive Pills: These pills contain levonorgestrel and should