9.4 Contraception, Emergency Contraception & Sexually Transmitted Infections

Contraception, Emergency Contraception & Sexually Transmitted Infections

Contraceptive counselling, emergency pregnancy prevention, and genitourinary medicine form core components of women's and sexual health in UK clinical practice. Clinicians must apply the UK Medical Eligibility Criteria for Contraceptive Use (UKMEC) to ensure safe prescribing and execute time-critical interventions for emergency contraception and sexually transmitted infections (STIs).

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UK Medical Eligibility Criteria (UKMEC) & Combined Hormonal Contraception

The Faculty of Sexual and Reproductive Healthcare (FSRH) defines four UKMEC categories to guide prescribing safety:

• UKMEC 1: A condition for which there is no restriction for the use of the contraceptive method.
• UKMEC 2: A condition where the advantages of using the method generally outweigh the theoretical or proven risks.
• UKMEC 3: A condition where the theoretical or proven risks usually outweigh the advantages of using the method (specialist consultation required; method not recommended unless other options unavailable or declined).
• UKMEC 4: A condition that represents an unacceptable health risk (absolute contraindication; the method must NOT be used).

Combined Hormonal Contraception (CHC: COCP, Transdermal Patch, Vaginal Ring)

Combined hormonal methods contain both an oestrogen (ethinylestradiol or estradiol) and a progestogen. Oestrogen promotes hepatic production of clotting factors (fibrinogen, factors VII, VIII, X) and suppresses antithrombin III, increasing thromboembolic and cardiovascular risk.

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Missed Pill Rules & Patient Guidance

Standard 21-Day Monophasic Combined Oral Contraceptive (COCP)

A pill is considered "missed" if taken more than 24 hours late (i.e., more than 48 hours since the last pill was ingested).

• ONE Pill Missed (24–48 hours late):
  • Action: Take the delayed/missed pill immediately (even if this means taking two pills in one day), then continue the remaining pills at the usual time.
  • Extra Precautions: No additional barrier contraception is required; contraceptive efficacy is maintained.
• TWO OR MORE Pills Missed (≥ 48 hours late):
  • Action: Take the most recently missed pill immediately; discard any earlier missed pills. Continue taking subsequent pills at the regular daily time.
  • Extra Precautions: Use condoms (or abstain) for the next 7 consecutive days.
  • Critical Timing Rules:
    • Missed in Week 1 (Days 1–7): If unprotected sexual intercourse (UPSI) occurred during the 7-day pill-free break or during Week 1, emergency contraception is indicated.
    • Missed in Week 2 (Days 8–14): If the 7 pills preceding the missed pills were taken correctly, no emergency contraception is needed; maintain condoms for 7 days.
    • Missed in Week 3 (Days 15–21): Finish the current active pack and OMIT the upcoming 7-day pill-free interval, starting the next pack immediately the following day.

Progestogen-Only Pill (POP)

• Traditional POP (Levonorgestrel / Norethisterone): 3-hour missed pill window.
• Desogestrel POP (Cerazette 75 mcg): 12-hour missed pill window (inhibits ovulation in >97% of cycles).
• Drospirenone POP (Slynd): 24-hour missed pill window.
• Action when POP is Missed Beyond the Window: Take the missed pill immediately, continue the pack, and use barrier contraception (condoms) for 48 hours (2 days). If UPSI occurred after the missed pill before 48 hours of compliant use has elapsed, emergency contraception is required.

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Long-Acting Reversible Contraception (LARC)

LARC methods have the highest real-world efficacy because they are independent of user compliance:

• Copper Intrauterine Device (Cu-IUD): Non-hormonal device releasing copper ions that impair sperm motility and induce local sterile inflammatory endometrial changes preventing blastocyst implantation. Duration: 5 to 10 years. May cause heavier, more painful menses.
• Levonorgestrel Intrauterine System (52 mg LNG-IUS / Mirena): Locally releases levonorgestrel to induce profound endometrial atrophy, thickening of cervical mucus, and variable anovulation. Duration: 5 to 8 years. Dramatic reduction in menstrual blood loss (>80% develop oligomenorrhoea or amenorrhoea).
• Progestogen Subdermal Implant (Nexplanon): Single rod containing 68 mg etonogestrel inserted into the upper inner arm. Duration: 3 years. High efficacy; primary side effect is unpredictable irregular spotting or prolonged amenorrhoea.
• Depot Medroxyprogesterone Acetate (DMPA / Depo-Provera): Intramuscular injection (150 mg) repeated every 13 weeks (FSRH: can be given up to 14 weeks without extra precautions). Delays return of fertility by up to 12 months after discontinuation; associated with transient reduction in bone mineral density (requires clinical review every 2 years).

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Emergency Contraception (EC)

Three emergency contraceptive modalities are available in the UK, each with distinct mechanisms, windows of efficacy, and drug interactions:

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Sexually Transmitted Infections (STIs) & Prophylaxis

1. Chlamydia trachomatis

• Presentation: Most common bacterial STI in the UK. Up to 80% of women and 50% of men are asymptomatic. Symptoms include abnormal vaginal discharge, dysuria, intermenstrual bleeding, or post-coital bleeding; in men, urethral discharge and dysuria. Complications include PID, ectopic pregnancy, tubal factor subfertility, and epididymo-orchitis.
• Diagnosis: First-catch urine in men; vulvovaginal swab for Nucleic Acid Amplification Testing (NAAT) in women.
• Treatment (BASHH):
  • First-line: Oral Doxycycline 100 mg twice daily for 7 days.
  • Second-line / Pregnancy / Allergy: Oral Azithromycin 1 g stat followed by 500 mg daily for 2 days, or oral Amoxicillin 500 mg TDS for 7 days, or Erythromycin 500 mg QDS for 7 days.

2. Neisseria gonorrhoeae

• Presentation: Gram-negative intracellular diplococci. Causes copious purulent urethral or vaginal discharge, dysuria, and pelvic pain. High resistance rates to penicillins, ciprofloxacin, and azithromycin.
• Diagnosis: Endocervical / vulvovaginal or first-catch urine NAAT plus culture and antimicrobial susceptibility testing.
• Treatment (BASHH): Intramuscular Ceftriaxone 1 g stat (single IM injection diluted in 1% lidocaine). Monotherapy is standard following revised resistance guidance.

3. Syphilis (Treponema pallidum)

• Primary Syphilis: Single, indurated, painless ulcer (hard chancre) with a clean base and raised rolled borders, accompanied by painless non-suppurative regional lymphadenopathy. Develops 2–3 weeks after exposure and heals spontaneously in 3–8 weeks.
• Secondary Syphilis (6–12 weeks later): Systemic haematogenous dissemination: non-pruritic maculopapular rash characteristically involving the palms of the hands and soles of the feet, condylomata lata (flat, moist, highly infectious wart-like lesions in genital skin folds), generalized lymphadenopathy, snail-track oral ulcers, and patchy alopecia.
• Tertiary Syphilis (years later): Gummas (granulomatous destructive lesions of skin/bone), cardiovascular syphilis (ascending aortic aneurysms, aortic regurgitation), and neurosyphilis (tabes dorsalis, Argyll Robertson pupils, dementia).
• Diagnosis: Dark-field microscopy or treponemal PCR of ulcer exudate. Serology: Treponemal tests (TPHA, TPPA, EIA; remain positive for life) confirm infection; non-treponemal tests (VDRL, RPR) reflect disease activity and monitor response to therapy.
• Treatment: Intramuscular Benzathine Penicillin G 2.4 million units stat (single IM dose for primary, secondary, and early latent syphilis; given weekly for 3 weeks in late latent syphilis). Doxycycline 100 mg BD for 14 days is used for penicillin-allergic patients. Patients must be warned about the Jarisch-Herxheimer reaction (acute febrile episode with chills and myalgia occurring within 24 hours of first penicillin dose).

4. HIV Post-Exposure Prophylaxis (PEP / PEPSE)

• Indicated following significant sexual or occupational exposure to body fluids from an individual known or suspected to be HIV-positive with a detectable viral load.
• Time Window: Must be commenced within 72 hours of exposure (greatest efficacy when initiated within 24 hours; ineffective after 72 hours).
• Regimen: A 28-day course of triple antiretroviral therapy (e.g., Tenofovir disoproxil + Emtricitabine [Truvada] once daily PLUS Raltegravir 1200 mg once daily or Dolutegravir 50 mg once daily).
• Baseline and 4–6 week follow-up HIV serology and renal profile monitoring are mandatory.

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Trichomoniasis

Trichomonas vaginalis is a sexually transmitted protozoan causing frothy yellow-green offensive vaginal discharge, vulval itching and soreness, and sometimes a "strawberry cervix"; men are often asymptomatic or have urethritis. Diagnose with a NAAT (or microscopy) on a vaginal swab. Treat with metronidazole (for example 400–500 mg twice daily for 7 days, per BASHH), advise avoiding sex until treatment of both partners is complete, and arrange partner notification and screening for other STIs.