Does Uterine Fibroids Affect IVF in Hong Kong? Fibroid Location, Size and IVF Success Rate

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Physician Decision Logic: How to Formulate an IVF Plan for Fibroid Patients

In reproductive clinics, the core criterion for whether patients with uterine fibroids can directly enter an IVF cycle is the relationship between the fibroid and the endometrium. Clinical decision-making revolves around three dimensions: the FIGO classification of the fibroid, the relative position of the fibroid to the endometrium, and whether the uterine cavity shape is intact. These three dimensions determine whether a patient needs fibroid treatment first or can proceed directly to ovarian stimulation.

For patients planning to undergo IVF in Hong Kong, the evaluation process is generally consistent with that in Mainland China. However, fertility centers in Hong Kong typically have stricter requirements for the uterine environment—most centers require confirmation of a normal uterine cavity shape, good endometrial blood flow, and no possibility of the fibroid compressing the endometrium or affecting the uterine cavity shape before embryo transfer. This standard stems from the clinical pathway for embryo transfer in Hong Kong: the widespread adoption of single embryo transfer strategies demands higher endometrial receptivity.

Impact of Uterine Fibroids on IVF Success Rate: Direct Answer

The impact of uterine fibroids on IVF success rates in Hong Kong cannot be generalized. According to existing clinical data, submucosal fibroids can reduce embryo implantation rates by approximately 40%–60%, with a significant decrease in clinical pregnancy rates; the impact of intramural fibroids is directly related to their size and location; subserosal fibroids generally do not affect IVF outcomes.

Specifically:

• Submucosal fibroids (FIGO types 0–2): Directly occupy the uterine cavity space, altering endometrial receptivity, making embryo implantation difficult. They must be removed via hysteroscopy before transfer. Post-surgery, depending on the fibroid depth and endometrial recovery, transfer is generally performed after waiting 1–3 menstrual cycles.
• Intramural fibroids (FIGO types 3–6): For those <4 cm in diameter and not compressing the endometrium, most studies show no significant impact on live birth rates; for those ≥4 cm or significantly compressing the endometrium, myomectomy is recommended, with IVF performed 3–6 months after recovery.
• Subserosal fibroids (FIGO types 7–8): Located on the outer layer of the uterus, not involving the endometrium or uterine cavity, they usually do not affect embryo implantation or development and require no special treatment.

In Hong Kong fertility centers, the threshold for treating intramural fibroids is slightly lower than in some Mainland centers—some Hong Kong doctors recommend preoperative evaluation for intramural fibroids ≥3.5 cm. This is related to the widespread use of single embryo transfer in Hong Kong and the higher demands on uterine cavity conditions.

Why Fibroids Affect IVF Outcomes: Mechanism Analysis

The mechanisms by which fibroids affect IVF outcomes mainly involve the following four aspects:

1. Altered Uterine Cavity Shape: Submucosal fibroids or larger intramural fibroids can distort the uterine cavity, preventing embryos from implanting in the correct position or causing developmental arrest after implantation due to insufficient blood supply.
2. Decreased Endometrial Receptivity: The endometrium surrounding fibroids often exhibits chronic inflammation, abnormal vascular distribution, and increased leukocyte infiltration, leading to abnormal expression of endometrial receptivity-related factors (such as integrins, osteopontin), hindering embryo-endometrial dialogue.
3. Local Blood Flow Abnormalities: Fibroids can compress branches of the uterine artery, increasing the resistance index of subendometrial blood flow, affecting embryo implantation and subsequent development.
4. Hormone Metabolism Interference: Some fibroid tissues have high aromatase activity, which can convert androstenedione to estrone, leading to abnormal local estrogen levels and further affecting cyclic endometrial changes.

Understanding these mechanisms helps explain why fibroids in different locations and sizes have vastly different impacts on IVF—it is not the fibroid itself that is frightening, but the degree to which it disrupts the uterine cavity environment and endometrial function.

Clinical Management Strategies for Fibroids in Different Locations

The table below summarizes the typical management approaches for fibroids of different FIGO classifications and corresponding recommendations for the Hong Kong IVF process:

It is important to note that some fertility centers in Hong Kong have stricter thresholds for treating intramural fibroids: even if the fibroid diameter is between 3.5–4.0 cm, if ultrasound suggests endometrial compression or the patient has a history of previous implantation failure, the doctor may recommend myomectomy first. Although this strategy extends the overall treatment time, it helps reduce the waste of embryos due to uterine cavity issues.

Fibroid Management in the Hong Kong IVF Process

For patients with uterine fibroids undergoing IVF in Hong Kong, the following process is typically followed:

• Initial Consultation and Evaluation: Submit previous medical records and ultrasound reports. The Hong Kong doctor will focus on the time of fibroid discovery, growth rate, previous surgeries, and symptoms such as menstrual changes.
• Specialized Fibroid Examinations: Including 3D transvaginal ultrasound, pelvic MRI (for precise measurement of fibroid size, location, and relationship with the endometrium), and hysteroscopy if necessary to directly observe the uterine cavity shape.
• Multidisciplinary Consultation: The reproductive specialist and hysteroscopic surgeon/gynecologist discuss together to determine whether the fibroid needs treatment and the method of treatment.
• Fibroid Treatment (if needed): Choose hysteroscopic or laparoscopic surgery based on fibroid location. Hysteroscopic techniques in Hong Kong commonly use cold knives or micro-scissors, causing less damage to the endometrium.
• Postoperative Recovery and Follow-up: After surgery, confirm via ultrasound or hysteroscopy that the uterine cavity shape has returned to normal and the endometrium is growing well before entering the IVF cycle.
• Start Ovarian Stimulation: After fibroid treatment is complete and the endometrium has recovered, proceed with routine ovarian stimulation, egg retrieval, embryo culture, PGT (if needed), and transfer.

Overall timeline: For patients who do not require fibroid treatment, it takes about 2–3 months from initial consultation to transfer; for patients who need fibroid treatment, an additional 3–6 months is required (depending on the surgical method and recovery).

Easily Overlooked Details

In clinical practice, several details are easily overlooked by patients but have a substantial impact on IVF outcomes:

• Fibroid Growth Rate: Even if a fibroid is currently small, rapid growth over the past 3–6 months (e.g., diameter increase ≥1 cm) suggests the fibroid may have active hormone receptor expression and could continue to grow during ovarian stimulation, affecting subsequent transfer. Hong Kong doctors usually ask patients to provide previous ultrasound reports to compare growth trends.
• Endometrial Blood Flow Assessment: Subendometrial blood flow may be abnormal in fibroid patients; simply looking at endometrial thickness is insufficient. Some Hong Kong centers routinely perform Doppler ultrasound of endometrial blood flow. A resistance index (RI) >0.7 indicates poor blood flow, requiring treatment before transfer.
• Relationship Between Fibroids and Embryo Freezing Strategy: For patients who need fibroid treatment first, it is recommended to retrieve eggs, form embryos, and freeze them first. After fibroid treatment and uterine cavity recovery, perform frozen embryo transfer. This avoids fibroid enlargement during ovarian stimulation affecting follicle development and does not delay embryo culture.
• Recognition of Examination Results Between Hong Kong and Mainland China: Some Hong Kong fertility centers accept MRI and ultrasound reports from Mainland tertiary hospitals, but hysteroscopy usually needs to be repeated in Hong Kong because different doctors have varying criteria for judging uterine cavity shape.

Common Pitfalls

Based on practitioner observations, patients with uterine fibroids undergoing IVF in Hong Kong are most prone to the following issues:

• Underestimating the Impact of Fibroids on the Uterine Cavity: Some patients think that if a fibroid is not large (e.g., 2–3 cm in diameter), it does not need treatment. However, if it is a submucosal fibroid or an intramural fibroid compressing the endometrium, even a small one can significantly affect implantation. Patients should ask the doctor to clearly state the FIGO classification of the fibroid, not just the diameter.
• Insufficient Waiting Time After Surgery: After myomectomy, the uterus needs time to recover. Some patients, eager to get pregnant, request transfer after only 1–2 months of rest. At this point, endometrial receptivity has not fully recovered, leading to a higher risk of embryo implantation failure. Generally, it is recommended to wait at least 3 menstrual cycles after surgery.
• Ignoring Fibroid Changes During Ovarian Stimulation: During ovarian stimulation, estrogen levels rise significantly, and some hormone-sensitive fibroids may grow rapidly. Hong Kong doctors usually monitor fibroid size during stimulation. If significant enlargement or symptoms like abdominal pain occur, the plan may need adjustment or the cycle may even be cancelled.
• Choosing a Mismatched Fertility Center: Different fertility centers in Hong Kong have varying experience and preferences for managing fibroids. Some centers excel in hysteroscopic techniques and are skilled at treating submucosal fibroids; others tend towards conservative observation for intramural fibroids. Patients should ask about the center's fibroid management strategy when choosing and select a doctor whose approach matches their condition.

Typical Scenario Analysis

Scenario 1: A 38-year-old woman, AMH 1.2 ng/mL, ultrasound shows a 1.5 cm submucosal fibroid (FIGO type 1), with a history of 2 failed transfers. The Hong Kong doctor recommends hysteroscopic myomectomy first, followed by frozen embryo transfer 3 months later. The patient worries that surgery will further reduce ovarian function, but the doctor explains: the submucosal fibroid is the main cause of previous transfer failures, and the surgery does not involve the ovaries, so it does not affect AMH. The patient successfully achieves pregnancy after surgery.

Scenario 2: A 35-year-old woman, AMH 3.8 ng/mL, intramural fibroid 4.2 cm (FIGO type 4), not compressing the endometrium. A Mainland doctor recommends direct transfer, while a Hong Kong doctor recommends myomectomy first. The patient chooses to follow the Hong Kong doctor's advice, undergoes transfer 6 months after surgery, and succeeds on the first attempt. This case illustrates differences in fibroid treatment thresholds between different medical systems; patients need to make decisions based on their own condition and risk preferences.

Scenario 3: A 42-year-old woman, AMH 0.6 ng/mL, subserosal fibroid 3 cm (FIGO type 7). The Hong Kong doctor recommends proceeding directly to the cycle for egg retrieval without fibroid treatment. The patient worries that the fibroid will affect success rates. The doctor explains that subserosal fibroids do not affect the uterine cavity, and age and ovarian reserve are the main limiting factors. The patient successfully retrieves eggs and forms usable embryos. This scenario reminds us: when ovarian reserve is limited, priority should be given to solving the main problem, avoiding wasting precious time on treating clinically insignificant fibroids.

This article is compiled by reproductive medicine editors, based on 2024 clinical guidelines and practices in Hong Kong fertility centers, and does not constitute individual medical advice. Please consult a licensed physician for specific diagnosis and treatment plans.