Adenomyosis has historically been called "endometriosis interna" — and while that term has largely been abandoned, it captures the essence of the condition: endometrial glands and stroma that have invaded deep into the muscular wall of the uterus (myometrium), where they don't belong.
For many years, adenomyosis was considered a condition of older, parous women and was rarely discussed in fertility consultations. That view has changed substantially. Improved imaging — particularly MRI — has revealed adenomyosis in a significant proportion of young, nulliparous women presenting for fertility evaluation. It is now recognized as a relevant contributor to implantation failure and pregnancy loss.
This guide explains what adenomyosis is, how it impairs fertility, how to diagnose it accurately, and what the evidence shows about treatment strategies before and during IVF.
What Is Adenomyosis?
Normally, the endometrium (uterine lining) is confined to the inner surface of the uterus, separated from the myometrium by a distinct boundary zone called the junctional zone (JZ). In adenomyosis, endometrial glands and stroma penetrate through the junctional zone and grow within the myometrial muscle. Like the endometrium itself, these ectopic glands respond to hormonal changes across the menstrual cycle — proliferating under estrogen, bleeding under progesterone withdrawal — creating inflammation, fibrosis, and uterine enlargement.
The prevalence of adenomyosis is difficult to estimate because histological diagnosis requires hysterectomy. In IVF populations specifically, MRI-based prevalence estimates range from 20–30%.
Focal vs. Diffuse Adenomyosis
Adenomyosis exists on a spectrum from focal (involving a discrete portion of the uterus, sometimes forming a localized adenomyoma) to diffuse (involving the entire myometrium).
| Type | Description | Fertility Impact |
|---|---|---|
| Focal adenomyosis | Localized cluster of ectopic glands in one region | Lower impact unless near endometrial cavity |
| Diffuse adenomyosis | Widespread glandular invasion throughout myometrium | More significant impact on uterine function |
| Adenomyoma | Localized adenomyotic nodule resembling a fibroid | Depends on location and size |
| Junctional zone thickening only | Thickened JZ without deep invasion (>12 mm on MRI) | Mild impact; may be early disease |
The deeper and more widespread the invasion, the greater the expected impact on implantation and pregnancy outcomes.
How Adenomyosis Impairs Fertility
Altered Uterine Contractility
The most well-studied mechanism by which adenomyosis reduces fertility is disruption of uterine peristalsis. The myometrium has coordinated wave-like contractions that serve several reproductive functions: propelling sperm toward the tubes in the pre-ovulatory phase and facilitating embryo implantation in the mid-luteal phase.
In women with adenomyosis, these contractions are dysrhythmic and hyperperistaltic — the uterus contracts too frequently and in disorganized patterns. This may actively expel embryos from the cavity before implantation is established.
Impaired Endometrial Receptivity
Adenomyosis is associated with altered expression of receptivity markers in the endometrium, including:
- Reduced pinopode (endometrial surface projection) formation during the implantation window
- Altered HOXA10 and HOXA11 expression (critical endometrial differentiation factors)
- Elevated prostaglandins and inflammatory cytokines at the endometrial surface
- Impaired trophoblast invasion at the implantation site
These changes affect the endometrium overlying and adjacent to adenomyotic deposits, reducing the probability of successful embryo attachment.
Mechanical Distortion
Significant adenomyosis causes uterine enlargement and may distort the endometrial cavity in ways that reduce the available implantation surface. A bulging posterior wall from diffuse posterior adenomyosis may compress the cavity or alter its shape.
Association With Miscarriage
Several studies document higher miscarriage rates in women with adenomyosis compared to controls. The mechanism likely relates to impaired trophoblast invasion and the dysfunctional uterine environment. Miscarriage rates in adenomyosis patients undergoing IVF have been reported in the range of 25–40% in some cohorts — higher than the background IVF miscarriage rate.
Diagnosis: Why MRI Is the Gold Standard
Adenomyosis cannot be reliably diagnosed by symptoms alone (though heavy, painful periods and an enlarged, tender uterus are suggestive). Definitive histological diagnosis requires excised tissue.
For clinical fertility purposes, imaging — particularly MRI — provides the most reliable non-invasive diagnosis.
Transvaginal Ultrasound
TVUS is widely accessible and a reasonable first-line evaluation. Sonographic features of adenomyosis include:
- Asymmetric myometrial thickening
- Heterogeneous myometrial texture ("Swiss cheese" appearance)
- Indistinct endometrial-myometrial border
- Myometrial cysts (small anechoic areas)
- Subendometrial lines and buds
Sensitivity and specificity of TVUS for adenomyosis are approximately 72% and 81% respectively in experienced hands, but results are highly operator-dependent.
MRI
MRI is the preferred imaging modality for adenomyosis in fertility evaluation because it:
- Directly visualizes the junctional zone (JZ) with high resolution
- Provides reproducible, objective measurements
- Identifies focal vs. diffuse disease and depth of invasion
- Distinguishes adenomyosis from fibroids when both may be present
- Is less operator-dependent than TVUS
MRI diagnostic criteria for adenomyosis:
- Junctional zone thickness >12 mm is the most widely used threshold
- JZ/outer myometrium ratio >40% suggests diffuse disease
- Focal hypointense signal within the myometrium on T2-weighted imaging
A JZ of 8–12 mm is considered borderline; clinical correlation is needed.
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GnRH Agonist Pretreatment Before IVF: What the Evidence Shows
GnRH agonists (such as leuprolide acetate, buserelin, or triptorelin) suppress estrogen production and create a hypoestrogenic state. Because adenomyosis is estrogen-dependent, GnRH agonist pretreatment is hypothesized to:
- Reduce adenomyotic tissue activity and inflammation
- Normalize junctional zone contractility
- Improve endometrial receptivity
Salim et al. (Fertil Steril) investigated GnRH agonist pretreatment for 3 months before IVF in women with adenomyosis and documented significantly higher clinical pregnancy rates compared to immediate IVF: approximately 45% vs. 18% per cycle in their cohort.
A larger meta-analysis of studies on GnRH agonist pretreatment in adenomyosis patients undergoing IVF consistently shows improved clinical pregnancy rates and lower miscarriage rates compared to no pretreatment. The most commonly used regimen is 3 months of GnRH agonist administration before beginning ovarian stimulation, though protocols range from 1 to 6 months.
Important caveats:
- Most evidence comes from retrospective studies; RCT data are limited.
- GnRH agonist pretreatment causes a hypoestrogenic side effect profile (hot flashes, bone loss with prolonged use, mood changes).
- The optimal duration is not established; 3 months is the most common protocol.
- GnRH agonist should not be used in women with very poor ovarian reserve, as some additional reserve loss may occur.
The Dienogest (a progestogen) and other hormonal pretreatment options are also being investigated, with promising early data.
The Freeze-All Strategy in Adenomyosis
A freeze-all strategy — freezing all embryos in the stimulation cycle and performing embryo transfer in a subsequent optimized frozen embryo transfer (FET) cycle — is strongly favored in women with adenomyosis for several reasons:
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Controlled hormonal environment for transfer. In a fresh transfer cycle, the high estrogen levels from ovarian stimulation may exacerbate adenomyotic activity and uterine hyperperistalsis. A FET cycle with controlled estrogen and progesterone supplementation may provide a more favorable uterine environment.
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Ability to add GnRH agonist pretreatment. Embryos can be banked, GnRH agonist pretreatment administered for 2–3 months, and then transfer performed after the treatment course — this is not possible with a fresh transfer.
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Reduced hyperperistalsis. The hormonal milieu of an artificial FET cycle appears to reduce uterine contractility compared to a stimulated fresh cycle.
Evidence specifically supporting freeze-all in adenomyosis includes retrospective cohort data showing higher live birth rates in FET vs. fresh transfer in adenomyosis patients, though this area requires more robust prospective data.
Surgical Management of Adenomyosis
Unlike fibroids, surgical excision of adenomyosis is technically challenging because there is no clear plane between adenomyotic tissue and normal myometrium — it blends into the surrounding muscle. Complete excision is rarely possible, and the uterine wall is significantly weakened by any surgical attempt.
Adenomyomectomy (excision of focal adenomyoma) is feasible in select cases and may be offered to:
- Women with focal adenomyosis causing significant cavity distortion
- Women with symptomatic adenomyomata that fail to respond to medical therapy
Reported pregnancy rates after adenomyomectomy are modest, and uterine rupture risk during subsequent pregnancy is a real concern. Women who undergo adenomyomectomy should be counseled about the potential need for cesarean delivery and close pregnancy monitoring.
For women who are not candidates for surgery or who have diffuse disease, medical pretreatment followed by IVF is the primary fertility strategy.
Adenomyosis and Endometriosis: Frequent Overlap
Adenomyosis and endometriosis co-occur in an estimated 20–50% of patients evaluated for endometriosis. When both conditions are present, the combined impact on implantation and fertility is more significant than either condition alone. The management approach typically addresses both — treating endometriosis surgically when indicated while applying GnRH agonist pretreatment and freeze-all strategies for the adenomyosis component. See our endometriosis and fertility guide for a detailed discussion of that condition.
Success Rates in Adenomyosis
Outcomes vary substantially based on disease severity and pretreatment:
| Situation | Approximate Clinical Pregnancy Rate per IVF Transfer |
|---|---|
| Adenomyosis, no pretreatment, fresh transfer | 18–25% |
| Adenomyosis, GnRH agonist pretreatment + FET | 35–48% |
| Focal adenomyosis, mild disease | Approaches non-adenomyosis baseline |
| Severe diffuse adenomyosis | 15–20% even with optimization |
These estimates are drawn from aggregate cohort data and are heavily age-dependent.
Key Takeaways
- Adenomyosis is endometrial tissue invading the myometrium; it causes dysrhythmic uterine contractions and impairs implantation.
- MRI with junctional zone measurement (>12 mm) is the most reliable non-invasive diagnostic tool.
- GnRH agonist pretreatment for 2–3 months before IVF significantly improves pregnancy rates in adenomyosis patients (Salim et al.).
- A freeze-all and FET strategy is preferred in adenomyosis to optimize the uterine environment at transfer.
- Adenomyomectomy is feasible for focal disease but technically complex and associated with uterine rupture risk in pregnancy.
- Adenomyosis and endometriosis frequently coexist; management should address both conditions.
References
- Salim R, et al. A comparative study of the impact of adenomyosis on women's fertility and outcomes after IVF treatment. J Hum Reprod Sci. 2012;5(1):16–19.
- Benaglia L, et al. Adenomyosis and IVF outcomes. Curr Opin Obstet Gynecol. 2018;30(3):167–171.
- American Society for Reproductive Medicine. Adenomyosis and reproduction: a committee opinion. Fertil Steril. 2012;98(3):591–598.
- Vercellini P, et al. Adenomyosis and endometriosis: related diseases or diverging phenotypes? Hum Reprod. 2009;24(11):2622–2627.
- Younes G, Tulandi T. Effects of adenomyosis on in vitro fertilization treatment outcomes. J Minim Invasive Gynecol. 2017;24(5):724–730.
Frequently Asked Questions
Does adenomyosis always cause infertility?
No — adenomyosis does not inevitably cause infertility. Many women with adenomyosis conceive naturally or with minimal assistance. However, research suggests adenomyosis is more common among infertile women than in the general population, and the condition can impair implantation, increase miscarriage risk, and reduce IVF success rates. The impact depends on the extent and type of adenomyosis (focal vs. diffuse) and whether other conditions like endometriosis are present.
How does adenomyosis affect IVF success rates?
Studies show that adenomyosis is associated with a 28–30% reduction in clinical pregnancy rates and live birth rates per IVF cycle compared to women without adenomyosis. The primary mechanism appears to be impaired uterine receptivity — adenomyosis alters the endometrial environment, gene expression, and immune function in ways that make implantation more difficult. Frozen embryo transfer (FET) in a "downregulated" cycle (using GnRH agonist pre-treatment) may mitigate some of this impact.
Can adenomyosis be treated before IVF to improve success?
Evidence suggests that GnRH agonist pre-treatment (Lupron) for 2–6 months before IVF may improve outcomes in women with adenomyosis by reducing lesion size and normalizing the endometrial environment. Some studies show a 2–4 fold improvement in pregnancy rates with this approach. Surgical treatment (uterus-sparing adenomyomectomy) remains controversial — it carries significant risks to uterine integrity and is not standard practice before IVF.
Does focal adenomyosis affect fertility more than diffuse adenomyosis?
The relationship between adenomyosis type and fertility impact is not fully established. Some research suggests diffuse adenomyosis has a greater impact on IVF outcomes than focal disease, potentially because it affects a larger proportion of the myometrium and endometrium. However, both types have been associated with reduced fertility compared to women without adenomyosis. The proximity of lesions to the endometrial cavity may be more important than diffuse vs. focal classification.
What symptoms suggest I might have adenomyosis?
Classic symptoms include: heavy menstrual bleeding (menorrhagia), severe menstrual cramps (dysmenorrhea), pelvic pain throughout the cycle, and a diffusely enlarged "boggy" uterus on examination. However, adenomyosis is often asymptomatic or has subtle symptoms, and up to 30% of women with adenomyosis have no symptoms at all. Diagnosis is typically made by MRI (most accurate) or transvaginal ultrasound in experienced hands.
Is adenomyosis the same as endometriosis?
No — they are related but distinct conditions. Both involve endometrial-type tissue growing where it shouldn't, but the location differs. In endometriosis, this tissue grows outside the uterus (on ovaries, fallopian tubes, peritoneum). In adenomyosis, it grows within the muscular wall (myometrium) of the uterus itself. The two conditions frequently coexist — studies suggest 20–40% of women with endometriosis also have adenomyosis.
