What is the best course of action for a female patient of reproductive age with a history of inconsistent oral contraceptive (OC) pill use, who had unprotected intercourse last night and has no known contraindications to emergency contraception?

Emergency Contraception Should Be Offered Immediately

This patient requires emergency contraception as soon as possible, ideally within 24 hours but no later than 120 hours (5 days) after unprotected intercourse. 1, 2

Recommended Emergency Contraception Options (in order of effectiveness)

First-Line: Copper IUD (Most Effective)

• The copper IUD is the most effective emergency contraceptive method available and can be inserted within 5 days of unprotected intercourse 1, 3, 4
• Provides the added benefit of ongoing highly effective contraception for up to 10 years 5, 6
• Can be inserted beyond 5 days after intercourse if the day of ovulation can be estimated, as long as insertion occurs ≤5 days after ovulation 1
• Contraindicated if puerperal sepsis, septic abortion, or current STI risk 1

Second-Line: Ulipristal Acetate (UPA/ella) 30 mg

• UPA is more effective than levonorgestrel, especially when taken 72-120 hours after intercourse 1, 5
• Take one 30 mg tablet orally as soon as possible within 120 hours (5 days) of unprotected intercourse 2
• Can be taken with or without food at any time during the menstrual cycle 2
• More effective than levonorgestrel in obese women (BMI >25 kg/m² or weight >75 kg) 5, 6
• Requires prescription 5, 7

Third-Line: Levonorgestrel (Plan B) 1.5 mg

• Take 1.5 mg as a single dose (or 0.75 mg twice, 12 hours apart) as soon as possible within 72 hours 1, 7
• Available over-the-counter for all ages 5
• Effectiveness declines significantly after 72 hours 1, 5
• May be less effective in women weighing >75 kg or BMI >25 kg/m² 5, 6

Last Resort: Yuzpe Regimen (Combined Estrogen-Progestin)

• 100 μg ethinyl estradiol plus 0.50 mg levonorgestrel, repeated 12 hours later 1
• Less effective than other methods and causes more nausea and vomiting 1, 3
• Only use if dedicated EC methods unavailable 6

Critical Timing Considerations

• All emergency contraceptives should be taken as soon as possible - effectiveness decreases with time 1, 2
• Levonorgestrel users who took it within 72 hours were significantly less likely to become pregnant than those who took it after 72 hours (RR 0.51) 3
• UPA maintains effectiveness throughout the 120-hour window better than levonorgestrel 1, 5

Important Management After EC Use

If UPA (ella) is chosen:

• Do not initiate or resume hormonal contraception for 5 days after taking UPA 2
• Use reliable barrier method (condoms) until next menstrual period 2
• Progestin-containing contraceptives may impair UPA's ability to delay ovulation if started too soon 2

If Levonorgestrel is chosen:

• Can start or resume hormonal contraception immediately 8
• Use backup contraception (condoms) for 7 consecutive days after starting hormonal method 8

If vomiting occurs:

• If vomiting occurs within 3 hours of taking oral EC, consider repeating the dose 2

Follow-Up and Monitoring

• If menses is delayed by more than 1 week beyond expected date, rule out pregnancy 2
• Evaluate for ectopic pregnancy if patient becomes pregnant or complains of lower abdominal pain after taking EC 2
• Counsel that EC does not protect against STIs/HIV 2
• Rapid return of fertility occurs after EC use - subsequent acts of intercourse require reliable barrier contraception until next menses 2

Special Considerations for This Patient

Given the history of inconsistent oral contraceptive use:

• Consider transitioning to a long-acting reversible contraceptive (LARC) method such as IUD or implant after EC use 8
• If copper IUD is chosen for EC, it can remain in place for ongoing contraception 5, 6
• Women who frequently miss pills should consider methods less dependent on user adherence 1

Common Pitfalls to Avoid

• Do not delay EC provision while waiting for pregnancy test if intercourse occurred within 5 days 1
• Do not start progestin contraception immediately after UPA - wait 5 days 2
• Do not assume levonorgestrel is adequate for obese women - prefer UPA or copper IUD 5, 6
• Do not forget to counsel about barrier contraception until next menses 2