In a 41-year-old woman seeking contraception with no abnormal uterine bleeding or menstrual irregularities, what is the most appropriate investigation before initiating contraception?

No Routine Investigation Required Before Prescribing Contraception

In a healthy 41-year-old woman requesting contraception without abnormal uterine bleeding or menstrual irregularities, no specific investigation from the options listed (FSH, TSH, transvaginal ultrasound, or endometrial biopsy) is routinely required before initiating contraception. The correct answer is effectively "none of the above."

Evidence-Based Rationale

Minimal Pre-Contraception Requirements

• Blood pressure measurement is the only essential examination before initiating combined hormonal contraception 1
• Pregnancy testing should be performed only if clinically indicated based on history—routine pregnancy testing for every woman is unnecessary 1
• Weight and BMI measurement are not required to determine medical eligibility for any contraceptive method, though baseline measurement may help monitor changes over time 1

Examinations NOT Required

The CDC's U.S. Selected Practice Recommendations explicitly state that the following are not needed routinely to provide contraception safely to a healthy client 1:

• Pelvic examinations (unless inserting an IUD or fitting a diaphragm) 1
• Cervical cytology or cancer screening 1
• Laboratory tests for glucose, lipids, liver enzymes, hemoglobin, or thrombogenic mutations 1
• HIV screening 1

Why the Listed Options Are Inappropriate

FSH (Option A): FSH testing is relevant only for infertility evaluation 1 or assessing menopausal status—neither applies to this asymptomatic 41-year-old seeking contraception.

TSH (Option B): Thyroid function testing is indicated when evaluating abnormal uterine bleeding or ovulatory dysfunction 2, 3, not for routine contraception initiation in an asymptomatic woman. While thyroid disorders can affect menstrual patterns 1, screening is not required before contraception in the absence of symptoms.

Transvaginal Ultrasound (Option C): Pelvic ultrasound is the first-line imaging for abnormal uterine bleeding 2, 4, 5, not for routine contraception. The question explicitly states no AUB or menstrual irregularities exist.

Endometrial Biopsy (Option D): Endometrial sampling is indicated for women ≥45 years with abnormal bleeding 3, postmenopausal bleeding 3, 6, or specific risk factors for endometrial cancer 3—none of which apply to this asymptomatic patient.

Clinical Algorithm for Contraception Initiation

Step 1: Medical History

• Assess for contraindications to specific contraceptive methods using U.S. Medical Eligibility Criteria 1
• Screen for cardiovascular risk factors, thrombotic risk, migraine with aura, breast cancer history, liver disease 1
• Review current medications for potential interactions 1

Step 2: Targeted Physical Assessment

• Measure blood pressure if considering combined hormonal contraception 1
• Bimanual examination and cervical inspection only if inserting an IUD 1
• No pelvic examination required for pills, patch, ring, injection, or implant 1

Step 3: Pregnancy Assessment

• Use clinical history to determine if pregnancy is reasonably excluded 1
• Perform urine β-hCG only if history suggests possible pregnancy 1

Step 4: Provide Contraception

• Offer the chosen method immediately if no contraindications identified 1
• Provide counseling on correct use and expected side effects 1

Common Pitfalls to Avoid

Creating unnecessary barriers: Requiring pelvic exams, Pap smears, or laboratory tests before contraception creates logistical, emotional, and economic barriers—particularly for adolescents and low-income women who have the highest rates of unintended pregnancy 1. These unnecessary requirements delay access to contraception without improving safety.

Confusing screening with contraception initiation: The investigations listed (FSH, TSH, ultrasound, endometrial biopsy) are appropriate for evaluating symptomatic patients with menstrual disorders or bleeding abnormalities 2, 3, 7, not for routine contraception in healthy women.

Over-medicalizing contraception: The evidence strongly supports a streamlined approach that removes barriers while maintaining safety 1. Contraception can be safely initiated based on history and blood pressure alone for most methods.