AMH and AFC Discordance: Which to Trust When Numbers Don't Match? Why it Happens.

When evaluating ovarian reserve, blood Anti-Müllerian Hormone (AMH) levels and Antral Follicle Count (AFC) observed via transvaginal ultrasound are both vital. However, these values occasionally don't match, leaving many wondering which one to trust. Why does this AMH and AFC discordance happen? In this article, from an obstetrician-gynecologist's perspective, we'll explain the underlying physiological mechanisms and clinical interpretations. Your feelings of uncertainty are valid. Gain accurate knowledge to help you make informed decisions for your next steps on your TTC journey.

AMH and AFC: Their Roles and Characteristics

Both AMH and AFC are indirect indicators of the number of developing follicles, from primordial follicles (the raw material for eggs) to pre-antral and antral follicles, within the ovaries.

What is AMH (Anti-Müllerian Hormone)?

AMH is a hormone secreted by small, growing follicles within the ovaries. Its blood concentration is measured to assess ovarian reserve. It can be measured via a simple blood test and is not significantly affected by the menstrual cycle phase. Higher AMH values suggest a greater number of follicles remaining in the ovaries, but it does not directly reflect egg quality or the ease of getting pregnant.

What is AFC (Antral Follicle Count)?

AFC is determined by counting small follicles, typically 2mm to 10mm in size, visible in the ovaries during a transvaginal ultrasound scan, usually in the early follicular phase (menstrual days 2-5). This count suggests the number of follicles potentially available for ovulation in that cycle and serves as an ovarian reserve indicator similar to AMH. AFC provides more real-time information as it directly reflects the ovarian status for that specific cycle.

Reasons for Discordance Between AMH and AFC

It's not uncommon for AMH and AFC values to differ. Various factors can contribute to this discordance.

Influence of Measurement Timing and Method

AFC measurement is recommended during specific phases of the menstrual cycle; deviations can lead to fluctuating values. Furthermore, the experience of the sonographer and the quality of the ultrasound equipment can also cause variations in the number of visible follicles. While AMH is measured via a blood test and is considered more objective, slight differences in laboratory measurement methods can still have an impact.

Individual Variations in Follicle Development

Follicles do not always grow at a uniform pace. Some women might have high AMH levels but a low AFC. This could indicate that while there are many growing follicles secreting AMH, only a small number have matured to the antral follicle stage visible on ultrasound. The reverse can also occur.

Specific Conditions or Constitutions

In women with Polycystic Ovary Syndrome (PCOS), both AMH and AFC often show high values due to the presence of many small follicles, but discordance can still occur. Conditions like endometriosis or a history of ovarian surgery, which can affect ovarian blood flow or function, may also imbalance these two indicators.

Research by Zhang et al. reported observing AMH and AFC discordance in women undergoing in vitro fertilization, highlighting the ongoing discussion about its clinical significance.

Interpretation and Future Approaches When Discordance Occurs

When AMH and AFC values don't align, it's crucial to evaluate both pieces of information comprehensively, rather than solely relying on one as "correct."

Comprehensive Evaluation Using Multiple Indicators

In reproductive medicine, decisions are made by integrating multifaceted information, including not just AMH and AFC, but also age, menstrual cycle regularity, other hormone levels like FSH and LH, medical history, and lifestyle. This comprehensive approach is particularly helpful in devising a fertility treatment plan.

For example, if AMH is high but AFC is low, it suggests that fewer eggs might be retrieved during an IVF cycle than initially expected due to fewer visible follicles on ultrasound. Conversely, if AMH is low but AFC is high, it indicates a sufficient number of visible follicles, suggesting a potential positive response to treatment.

Detailed Consultation with Your Doctor

If you feel anxious due to discordant AMH and AFC values, discussing it thoroughly with a fertility specialist is paramount. Your doctor will assess your individual circumstances in detail, explain the implications of the discordance for your TTC journey, and help you determine the optimal treatment plan. Don't carry this vague anxiety alone; seeking expert advice can alleviate your emotional burden. For more detailed information and specialized advice on fertility, please visit our homepage. We offer personalized treatment tailored to each patient's unique situation. If you wish to learn more about your ovarian reserve, please consider scheduling a consultation.

Frequently Asked Questions (FAQ)

Q1: If AMH and AFC values differ significantly, which one should I prioritize?

A1: Rather than prioritizing one completely, it's crucial to consider both values comprehensively. AMH indicates overall ovarian reserve, while AFC offers a more real-time snapshot of the ovary's state in a given cycle. If there's discordance, it's important to explore the underlying reasons and, in consultation with a specialist, factor in more information like age, medical history, and other hormone levels to decide on a treatment plan.

Q2: How do AMH and AFC values change with age?

A2: Generally, both AMH and AFC tend to decrease with age. This decline is known to accelerate particularly after the mid-30s. However, there's significant individual variation; some younger women may have low values, while some older women maintain relatively high values. This is because the rate of ovarian aging differs from person to person.

Q3: Does a low AMH or AFC value mean that pregnancy will be difficult?

A3: Low AMH or AFC values suggest reduced ovarian reserve, but this doesn't necessarily mean pregnancy is impossible. These values are indirect assessments of egg "quantity," not direct reflections of egg "quality" or the likelihood of natural conception. Even with low values, a suitable and personalized treatment plan can offer a good chance of pregnancy.

Summary

AMH and AFC are two crucial indicators for evaluating ovarian reserve, but their values don't always align. Measurement timing, individual follicle development, and specific medical conditions can all contribute to this discordance. If you're experiencing discordant AMH and AFC values and feel anxious, it's vital not to struggle alone but to consult with a fertility specialist. A comprehensive, multi-faceted evaluation will help you receive the support needed to find the optimal treatment approach for you.

References

Zhang Y, et al. "Discordance between antral follicle counts and anti-Müllerian hormone levels in women undergoing in vitro fertilization." Reprod Biol Endocrinol. 2019. PMID: 31272468

Written by the same author — a general guide to preconception care and fertility planning: https://amazon.com/dp/B0F7XTWJ3X?tag=ttcguide-enblog-22