Amenorrhea and Oligomenorrhea

Introduction

Welcome to this comprehensive MCCQE1 preparation guide on amenorrhea and oligomenorrhea. This resource is tailored for Canadian medical students preparing for the Medical Council of Canada Qualifying Examination Part I (MCCQE1). We'll explore these conditions through a Canadian healthcare lens, emphasizing key concepts, diagnostic approaches, and management strategies relevant to the Canadian medical system.

Definitions and Classification

Amenorrhea

Amenorrhea is defined as the absence of menstruation. It is classified into two types:

1. Primary Amenorrhea: Absence of menarche by age 15 years or by more than 3 years after thelarche (breast development).
2. Secondary Amenorrhea: Absence of menses for 3 consecutive months in a woman who previously had regular periods, or 6 months in a woman with oligomenorrhea.

Oligomenorrhea

Oligomenorrhea is defined as infrequent menstrual periods, typically occurring at intervals of more than 35 days but less than 6 months.

Etiology

Understanding the causes of amenorrhea and oligomenorrhea is essential for MCCQE1 success. Here's a comprehensive list organized by anatomical level:

Diagnostic Approach

For MCCQE1 preparation, it's crucial to understand the Canadian approach to diagnosing amenorrhea and oligomenorrhea. Here's a step-by-step guide:

1. Detailed history: Including menstrual history, sexual activity, medications, and lifestyle factors.
2. Physical examination: Look for signs of androgen excess, thyroid abnormalities, and secondary sexual characteristics.
3. Pregnancy test: Always the first step in any woman of reproductive age with amenorrhea.
4. Hormonal evaluation:
   • FSH, LH, estradiol
   • Prolactin
   • TSH
   • Testosterone (total and free)
5. Imaging studies:
   • Pelvic ultrasound
   • MRI of the pituitary if indicated

Management

Management strategies in Canada focus on addressing the underlying cause and may include:

Canadian Guidelines

The Society of Obstetricians and Gynaecologists of Canada (SOGC) provides guidelines for the management of amenorrhea and oligomenorrhea. Key points include:

1. Evaluation of amenorrhea should begin by age 15 if no menses have occurred, or within 3 years of thelarche.
2. PCOS diagnosis in Canada follows the Rotterdam criteria, requiring two of three: oligo/anovulation, clinical/biochemical hyperandrogenism, and polycystic ovaries on ultrasound.
3. First-line treatment for PCOS in Canada often includes combined oral contraceptives and lifestyle modifications.

Key Points to Remember for MCCQE1

• Always consider pregnancy first in cases of amenorrhea.
• PCOS is the most common cause of oligomenorrhea in Canada.
• Functional Hypothalamic Amenorrhea is common in athletes and those with eating disorders.
• Canadian guidelines emphasize a stepwise approach to diagnosis, starting with least invasive tests.
• Management should address both the underlying cause and the patient's reproductive goals.

Sample Question

# Sample Question

A 22-year-old woman presents with absence of menses for the past 6 months. She reports significant weight loss over the past year due to intense training for a marathon. Her BMI is 18.5 kg/m². Physical examination is unremarkable. Pregnancy test is negative. Which one of the following is the most likely diagnosis?

- [ ] A. Polycystic Ovary Syndrome
- [ ] B. Premature Ovarian Insufficiency
- [ ] C. Functional Hypothalamic Amenorrhea
- [ ] D. Prolactinoma
- [ ] E. Asherman's Syndrome

Explanation

The correct answer is:

• C. Functional Hypothalamic Amenorrhea

Functional Hypothalamic Amenorrhea (FHA) is the most likely diagnosis in this case. The patient's history of significant weight loss, intense physical training, and low BMI are classic features of FHA. This condition results from suppression of the hypothalamic-pituitary-ovarian axis due to physical stress, psychological stress, or energy deficit.

PCOS (A) typically presents with obesity and signs of hyperandrogenism, which are not present here. Premature Ovarian Insufficiency (B) is less likely in a 22-year-old and would show elevated FSH levels. Prolactinoma (D) usually presents with galactorrhea and would be confirmed by elevated prolactin levels. Asherman's Syndrome (E) typically occurs after uterine instrumentation or infection and would not be associated with weight loss or exercise.

References

1. Reid, R. L., Wolfman, W., & Leyland, N. (2018). SOGC clinical practice guideline: Menstrual suppression in special circumstances. Journal of Obstetrics and Gynaecology Canada, 40(2), e51-e69.

2. Gordon, C. M., Ackerman, K. E., Berga, S. L., et al. (2017). Functional Hypothalamic Amenorrhea: An Endocrine Society Clinical Practice Guideline. The Journal of Clinical Endocrinology & Metabolism, 102(5), 1413-1439.

3. Teede, H. J., Misso, M. L., Costello, M. F., et al. (2018). Recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome. Human Reproduction, 33(9), 1602-1618.

4. The Society of Obstetricians and Gynaecologists of Canada. (2021). Clinical Practice Guidelines. Retrieved from https://www.sogc.org/en/content/guidelines-jogc/guidelines-and-consensus-statements_1.aspx (opens in a new tab)

5. Medical Council of Canada. (2021). Objectives for the Qualifying Examination. Retrieved from https://mcc.ca/objectives/ (opens in a new tab)