Emergency Contraception

1. THE 2-MINUTE PHYSIOLOGY (Rapid Pathophysiology)

• Luteinizing Hormone (LH) Surge Inhibition: Oral emergency contraceptives (ECs) primarily function by delaying or inhibiting ovulation before fertilisation occurs. Levonorgestrel (a progestin) acts by blocking the LH surge, which prevents follicular rupture and the release of an egg.
• Post-Surge Ovulation Delay: Ulipristal acetate (a selective progesterone receptor modulator) possesses superior efficacy because it delays follicular rupture both during the pre-ovulation phase and after the LH surge has already commenced, a window where levonorgestrel is ineffective.
• Sperm and Implantation Barrier: The copper intrauterine device (IUD) acts locally within the uterine cavity. It induces a sterile inflammatory response that is toxic to gametes, thereby inhibiting sperm function, hindering fertilised egg transport, and potentially preventing endometrial implantation.
• Enzymatic Degradation (CYP450 Pathway): Oral emergency contraceptives are metabolised in the liver via the cytochrome P450 enzyme system. Consequently, concurrent administration of cytochrome P450 enzyme inducers (such as carbamazepine, phenytoin, rifampin, or St. John's wort) accelerates drug clearance and significantly decreases EC efficacy.

2. THE BEDSIDE ACTION PLAN (Rapid ER Management)

• Step 1: Confirm Pregnancy Status: Obtain an immediate urine or serum pregnancy test prior to administration; emergency contraception is ineffective and contraindicated in patients with an established pregnancy.
• Step 2: Resuscitate and Address Concomitant Trauma: If the presentation involves sexual assault, manage immediate life threats (ABCs) first, and evaluate for genital or extragenital lacerations and trauma.
• Step 3: Administer Selected Emergency Contraception:
• Ulipristal Acetate (Preferred Oral): Administer 30 mg PO once up to 120 hours after unprotected intercourse. This is the preferred oral regimen if 72 to 120 hours have elapsed or if the patient is overweight or obese (BMI >26 to 35 kg/m²). Note: Requires a prescription.
• Levonorgestrel (Plan B): Administer 1.5 mg PO once (or 0.75 mg at 1 and 12 hours) up to 72 hours (with decreased efficacy up to 120 hours). This is available over-the-counter.
• Copper IUD (Paragard): Coordinate insertion of a copper 380 mm² IUD within 120 hours. This is the most effective method overall.
• Step 4: Provide Prophylactic Antiemetics: Co-administer meclizine 50 mg, metoclopramide 10 mg, or ondansetron 4 mg to prevent drug-induced nausea and vomiting.
• Step 5: Enforce the 2-Hour Vomiting Rule: Instruct the patient that if vomiting occurs within 2 hours of taking any oral EC, they must return to the ED to receive a replacement dose.

3. THE DIAGNOSTIC GRID (Differential Diagnosis & Workup)

Top 4 Can't-Miss Differential Diagnoses:

1. Ruptured Ectopic Pregnancy: Can present with pelvic pain, vaginal bleeding, or syncope. Must be ruled out via hCG testing and pelvic ultrasound if symptomatic.
2. Septic Abortion/Miscarriage: Suspect in patients with fever, pelvic pain, peritonitis, and malodorous or purulent vaginal discharge [102, e107].
3. Pelvic Inflammatory Disease (PID) / Tubo-Ovarian Abscess (TOA): Presents with bilateral lower abdominal pain, cervical motion tenderness, and adnexal tenderness.
4. Extragenital and Genital Trauma: In cases of sexual assault, evaluate for internal vaginal/anal lacerations, rectal injury, and extensive blunt force trauma.

Prioritized Diagnostic Workup Strategy:

• hCG Pregnancy Test: Mandatory initial screening tool for all female patients of reproductive potential.
• Sexually Transmitted Infection (STI) Panel: Offer universal screening for Neisseria gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis, syphilis, HIV, and hepatitis B and C.
• Targeted Pelvic Exam with Chaperone: A speculum or bimanual pelvic examination is not routinely necessary for a standard EC request, but is strictly indicated if there are symptoms of vaginal trauma, unexplained bleeding, pelvic pain, purulent discharge, or if a formal forensic exam is requested.
• Transvaginal Ultrasound (TVUS): Indicated if there is clinical concern for ectopic pregnancy, TOA, or septic abortion.

4. THE VISUAL BOARD (ECG / POCUS / Imaging)

• POCUS Ultrasound Checklist (Mimic Rule-Out):

    1.  *Intrauterine Pregnancy (IUP)*: Look for a gestational sac containing a **yolk sac or a fetal pole** with or without cardiac activity within the endometrial cavity.
    2.  *Ectopic Pregnancy*: Look for an empty uterus with a serum hCG above the machine’s discriminatory zone (typically 1500–2000 mIU/mL), an adnexal mass/chorionic ring, or **moderate-to-large free fluid** in the Pouch of Douglas.
    3.  *Tubo-Ovarian Abscess*: Identify a complex, thick-walled adnexal mass with internal debris or a fluid-filled, dilated fallopian tube.

• Forensic Documentation Checklist:
• If evaluating a victim of sexual assault, never interpret or label wounds as "entrance" or "exit" in the medical record, and do not estimate bullet caliber.
• Chart detailed, objective descriptions of the physical characteristics and anatomical locations of all injuries, and document them using color photography.

5. THE SCORING MATRIX (Risk Stratification & Guidelines)

1. Body Mass Index (BMI) Risk Stratification

The patient's BMI dictates the choice of oral emergency contraception to prevent therapeutic failure:

| Patient BMI Cutoff | Preferred EC Modality | Clinical Efficacy Considerations |
| :--- | :--- | :--- |
| **BMI < 26 kg/m²** | Levonorgestrel 1.5 mg **or** Ulipristal acetate 30 mg | Both oral formulations demonstrate maximum baseline efficacy. |
| **BMI 26–35 kg/m²** | **Ulipristal acetate 30 mg** | Ulipristal acetate is significantly more effective than levonorgestrel in this range. |
| **BMI > 35 kg/m²** | **Copper IUD** (if feasible) or **Ulipristal acetate** | Oral emergency contraception has significantly diminished efficacy. The copper IUD retains >99% efficacy regardless of patient weight. |

2. Specific Contraindication Guidelines

• Ulipristal Acetate: Strictly contraindicated if >120 hours have elapsed since unprotected intercourse. It is relatively contraindicated in active breastfeeding because it has not been adequately tested; the CDC recommends discarding breast milk for 24 hours after use.
• Levonorgestrel: Efficacy decreases progressively over time; it is not recommended if >72 hours have elapsed, though it can be administered with reduced efficacy up to 120 hours.
• Estrogen-Containing Regimens (Yuzpe Method / Sprintec): Contraindicated in patients with a history of venous thromboembolism (DVT/PE), ischemic stroke, coronary artery disease, breast or endometrial cancer, severe decompensated cirrhosis, or uncontrolled hypertension (BP \(\ge\) 160/100 mm Hg).

6. THE DANGER ZONE (Pitfalls & Critical Actions)

Deadly Cognitive Traps & Trainee Errors:

• The Progestin Contraceptive Trap: Allowing a patient who took ulipristal acetate to immediately resume her daily combined oral contraceptive pills. Daily contraceptive pills must be delayed for exactly 5 days after taking ulipristal. Resuming progestin-containing pills too early blocks ulipristal's ability to inhibit ovulation, leading to EC failure and unintended pregnancy.
• The Breastfeeding Time Deception: Failing to differentiate breastfeeding guidelines. If a breastfeeding patient takes levonorgestrel, she must "pump and dump" for only 8 hours. If she takes ulipristal, she must "pump and dump" and discard milk for 24 hours.
• The Toxic Dose Delusion: Failing to consider that in regions with severely restricted abortion access, patients may present having ingested toxic doses of oral emergency contraceptives in desperate, dangerous attempts to terminate an existing, unwanted pregnancy.
• The SART Delay Pitfall: Delaying the administration of emergency contraception or medical stabilization while waiting for a forensic SART team to arrive.

Board-Mandated Critical Actions:

• Obtain a pregnancy test on all women of reproductive age before prescribing or administering emergency contraception.
• Mandatorily screen all patients presenting for EC for intimate partner violence (IPV) and human trafficking, as survivors in these scenarios frequently experience reproductive coercion and unprotected intercourse.
• Prescribe a prophylactic antiemetic alongside oral emergency contraceptives to prevent vomiting and subsequent dose loss.
• Instruct all patients starting or resuming daily oral contraceptives to use alternative barrier methods (such as condoms) or practice abstinence for 7 days.
• Instruct the patient to take a home pregnancy test if her subsequent menstrual period is more than 7 days late.

7. MCQ MASTERCLASS (Written Exam Tips)

• High-Yield "Buzzwords":
• "Approved up to 120 hours with enhanced efficacy over progestins" \(\rightarrow\) Ulipristal acetate (Ella).
• "Metabolised by Cytochrome P450" \(\rightarrow\) Antiepileptic drugs (e.g., phenytoin, carbamazepine) decrease the efficacy of oral emergency contraceptives.
• "Ethinyl estradiol plus levonorgestrel in two split doses" \(\rightarrow\) The Yuzpe Method. This is the least effective method and has the highest rate of nausea and vomiting.
• The "Obese Patient" Trap:
• Questions will ask for the most appropriate oral EC for a patient with a BMI of 32 kg/m² presenting 48 hours after unprotected intercourse. The correct answer is Ulipristal acetate, as levonorgestrel has significantly diminished efficacy in patients with a BMI \(\ge\) 30 kg/m².
• The "DVT Contraindication" Distractor:
• Questions will present a patient with a history of DVT/PE requesting emergency contraception. The distractors will suggest that all hormonal ECs are contraindicated. This is false. While combined estrogen-progestin pills (Yuzpe) are contraindicated, progestin-only (levonorgestrel) and progestin antagonists (ulipristal) do not carry the estrogen-related thromboembolic contraindications and are safe to use.

8. THE BOARDROOM SCRIPT (OSCE & Oral Board Tips)

Mandatory OSCE Communication Actions:

• Coordinate the Forensic SART Team: "I am stating for the record that while forensic evidence collection and SART mobilization are important, medical stabilization, trauma evaluation, and the administration of emergency contraception take absolute priority and will not be delayed".
• Enforce Trauma-Informed Examination Principles: "I will perform all physical and pelvic examinations in a private room with a chaperone present, ensuring that a supportive, trauma-informed environment is maintained at all times".

High-Yield Phrasing to Use under High-Stress Testing:

• Ulipristal Counseling and Daily Pill Resumption: "I am prescribing ulipristal acetate 30 mg PO as a single dose for emergency contraception. Because this medication is a progesterone receptor modulator, I will explicitly instruct the patient that she must wait exactly 5 days before resuming her daily combined oral contraceptive pills to prevent neutralizing the emergency contraception. I will instruct her to use backup barrier contraception, such as condoms, for the next 7 days".
• Vomiting and Antiemetic Prophylaxis script: "To ensure therapeutic success, I will co-administer ondansetron 4 mg intravenously or meclizine 50 mg orally. I will counsel the patient that if she experiences emesis within 2 hours of taking her emergency contraception, she must contact the emergency department immediately to receive a replacement dose".
• Social Safety Net and Trafficking Screen: "I recognize that patients presenting for emergency contraception represent a high-risk group for reproductive coercion. I will screen this patient privately for intimate partner violence and human trafficking. I will offer a comprehensive STI screening panel and arrange close outpatient gynecological follow-up in 3 weeks to confirm menses or check a repeat pregnancy test".