Targeted management of adenomyosis: frozen embryo transfer outcomes with GnRH-agonist and letrozole therapy: a case series

Abstract

Background

Adenomyosis negatively impacts fertility treatment outcomes by lowering clinical pregnancy rates, reducing live birth rates, and increasing miscarriage rates following in vitro fertilization. Hormonal suppression therapy has emerged as a preferred treatment for patients with adenomyosis, particularly before endometrial preparation for frozen-thawed embryo transfer; however, the combination therapy for individualized patients can improve the outcomes. Here we present three cases in wherein we applied a combined protocol using GnRH agonists and letrozole for endometrial preparation in patients with severe adenomyosis undergoing euploid frozen embryo transfer with a single embryo.

Case presentation

Three women with Arabian (Emirati) ethnicity aged 31–32 year old with moderate and severe adenomyosis and histories of recurrent in vitro fertilization failures and miscarriages underwent a combined protocol using GnRH agonists and letrozole and diagnostic hysteroscopy with saline instillation followed by hormonal replacement therapy for euploid frozen embryo transfer. Our three cases resulted in deliveries at 36, 38, and 40 weeks.

Conclusions

Adenomyosis-related infertility remains a challenge. This case series supports the potential efficacy of hormonal suppression by combining GnRH agonists, aromatase inhibitors, and diagnostic hysteroscopy with saline irrigation prior to the endometrial preparation for euploid frozen embryo transfer in patients with adenomyosis. This protocol offers a promising alternative for cases unresponsive to standard treatments, although further research is warranted to refine guidelines on treatment duration and dosage.

Background

Adenomyosis is a condition when endometrial tissue, which typically lines the uterus, invades the uterine myometrial layer. Although approximately one in three patients with adenomyosis remains asymptomatic, many experience symptoms ranging from pelvic pain and infertility to heavy menstrual bleeding, which is the most common manifestation [1]. Traditionally, adenomyosis was diagnosed primarily through histopathological examination after hysterectomy; however, advances in pelvic imaging, such as magnetic resonance imaging (MRI) and transvaginal ultrasound (TVUS), have enabled earlier and more frequent diagnoses, including among younger patients [2].

Adenomyosis induces a range of changes within the uterus, including inflammation, abnormal uterine contractility, and adverse effects on fertility, which contribute to a higher risk of infertility and miscarriage. In particular, this condition also negatively impacts fertility treatment outcomes by lowering clinical pregnancy rates, reducing live birth rates, and increasing miscarriage rates following in vitro fertilization (IVF) [3–6]. Surgical correction is often challenging, with limited number of studies to objectively evaluate the clinical benefit, requiring considerable expertise [7]. Consequently, treatment approaches primarily focus on pharmaceutical interventions that target the hormonal imbalances underlying adenomyosis. Hormonal suppression therapy has emerged as a preferred treatment for patients with adenomyosis, particularly before endometrial preparation for frozen-thawed embryo transfer. However, recent evidence indicates that gonadotropin-releasing hormone agonist (GnRH-a) suppression alone, which suppresses the central axis of steroid production via anterior pituitary desensibilization, may have limited efficacy in improving IVF outcomes [8, 9]. To suppress local steroid production by adenomyotic tissue, new protocols have been developed that combine GnRH-a suppression with aromatase inhibitors to enhance treatment efficacy.

Here, we present three cases of adenomyosis in women with normal body mass indexes (BMIs) who experienced multiple IVF cycles, resulting in recurrent miscarriage. We discuss a protocol combining GnRH-a suppression with letrozole for endometrial preparation during euploid frozen-thawed embryo transfer to explore its potential benefits.

Case 1

A 32-year-old woman with Arabian (Emirati) ethnicity presented to our clinic in September 2023 with 6 years of secondary infertility. Her obstetric history included four pregnancies (gravida [G] 4 para [P] 1 abortus [A] 3), all of them achieved after IVF/intracytoplasmic sperm injection (ICSI) treatments: a late miscarriage at 21 weeks in 2014 followed by evacuation and curettage, the birth of a healthy daughter at 39 weeks in 2015, and two biochemical pregnancies after euploid frozen embryo transfers (eFETs) in 2017 and 2018. She had undergone elsewhere five IVF/ICSI cycles and a total of 13 euploid blastocysts transferred (including two fresh and the remainder as frozen transfers under Hormonal replacement therapy [HRT]). The thrombophilia and antiphospholipid syndrome panels were negative. The husband’s sperm analysis showed normozoospermia. Transvaginal ultrasound (TVUS) showed diffuse adenomyosis in the posterior uterine wall, including hyperechoic islands, myometrial cysts, and echogenic subendometrial glands, with a score of 7 [10] (detailed description in Tables 1 and 2 and Figs. 1 and 2).

Table 1.

Description of criteria, extension, and severity of adenomyosis

Schematic mapping system of adenomyosis severity		MUSA criteria for diagnosis of adenomyosis**		Extension of the disease
Diffuse adenomyosis	Diffuse inside the myometrium and thickening of the uterine walls	Direct features	Myometrial cysts, hyperechogenic islands, and echogenic subendometrial lines and buds	The extension of each type of adenomyotic lesion in the external myometrium and the JZ determines the grades and severity
	Diffuse adenomyosis of the JZ: diffuse inside the JZ and thickening of the JZ	Indirect features	Globular uterus, asymmetrical myometrial thickening, fan-shaped shadowing, translesional vascularity and irregular or interrupted JZ	Mild (< 25%) Moderate (25–50%) Severe (> 50%)
Focal adenomyosis	Focal lesions within the outer myometrium
	Focal adenomyosis of the JZ: focal lesion in the JZ
Adenomyoma

JZ, junctional zone; MUSA, morphological uterus sonographic assessment

^**MUSA criteria for diagnosis of adenomyosis. Adapted from Van den Bosch et al. [17]

Table 2.

Adenomyosis severity for the three cases based on the Lazzeri classification (2018) [10]

Case	Features	Score	Severity
1	Focal adenomyosis: two focal intramyometrial lesions (10 and 20 mm) Diffuse adenomyosis, with thickening of all the uterine walls Globally enlarged uterus	Focal: 3 Diffuse: 4	7 (severe)
2	Focal adenomyosis: two focal lesions (< 10 mm) Diffuse adenomyosis, affecting all the uterine walls Globally enlarged uterus	Focal: 2 Diffuse: 4	6 (moderate)
3	Focal adenomyosis: one focal lesion (< 10 mm) Diffuse adenomyosis, affecting all the uterine walls Globally enlarged uterus Junctional zone infiltration (JZ): > 50–80%	Focal: 1 Diffuse: 4 Junctional zone infiltration: 3	8 (severe)

Fig. 1.

Transvaginal ultrasound image of Case 1 showing diffuse adenomyosis (A) in the posterior uterine wall, hyperechoic islands, myometrial cysts, and echogenic subendometrial glands (B)

Fig. 2.

Diagnostic hysteroscopy image of Case 1 after hormonal suppression (A, B)

The couple underwent ovarian stimulation for IVF/ICSI using an antagonist protocol with 300 IU recombinant follicle-stimulating hormone (rFSH) (Gonal-f, Merck). A dual trigger was administered with triptorelin acetate (Gonapeptyl, 0.3 mg) and urinary human chorionic gonadotropin (uhCG) (Choriomon, 2500 IU), and 23 cumulus-oocyte complexes (COCs) were retrieved 36 h later, resulting in five euploid blastocysts (pre-implantation genetic testing for aneuploidy [PGT-A] performed with next-generation sequencing [NGS]), which were vitrified.

For endometrial preparation, she received triptorelin acetate (Decapeptyl, 3.75 mg) during the luteal phase, followed by daily letrozole (5 mg) for 1 month. A second GnRH agonist dose was given after 4 weeks, with diagnostic “irrigation” hysteroscopy performed prior to HRT initiation. She received estradiol (6 mg/day) for 10 days, resulting in a 7.9 mm triple-lined endometrium. Progesterone (Endometrin 100 mg, three times per day) was started, with an embryo transfer 120 h later, supported by additional intramuscular progesterone (100 mg every other day). The patient had a positive pregnancy and delivered a baby boy via cesarean section at 38 weeks.

Case 2

The second case involved a 31-year-old woman (G2A2) with Arabian (Emirati) ethnicity who presented to our clinic with a 5-year history of primary infertility. Her AMH level was 7.79 ng/mL. She had previously undergone one IVF cycle in another center, resulting in an embryo transfer without PGT-A that ended in an early miscarriage. A second miscarriage occurred in our clinic with HRT protocol. Her BMI was 23.3 kg/m², and she reported regular cycles. Her thrombophilia and antiphospholipid syndrome panels were negative. Her husband’s sperm analysis showed normozoospermia. During the TVUS, a globular uterus with diffuse adenomyosis was observed, with asymmetrical thickening, hyperechoic islands, and junctional zone anomalies, with a score of 6 [10] (detailed description in Tables 1 and 2 and Figs. 3 and 4).

Fig. 3.

Transvaginal ultrasound image of Case 2 showing diffuse adenomyosis, globular uterus (A), asymmetrical thickening, hyperechoic islands, and junctional zone anomalies (B)

Fig. 4.

Diagnostic hysteroscopy image of Case 2 after hormonal suppression. Arrows show hypovascularized areas compared to pre-suppression images (A, B)

The patient then underwent an antagonist IVF cycle with 300 IU rFSH (Gonal-f, Merck) and dual trigger (triptorelin acetate 0.3 mg and uhCG 2500 IU). Forty metaphase II (MII) oocytes were retrieved, resulting in 13 euploid embryos vitrified.

The first euploid frozen embryo transfer (eFET) was planned in a natural cycle yet was unsuccessful. The second eFET was planned under HRT but resulted in a clinical miscarriage. For the third eFET, hormonal suppression was performed following the same protocol as in Case 1: two doses of GnRH-a plus letrozole 5 mg for 1 month, followed by a diagnostic hysteroscopy before starting HRT. Endometrial thickness of 8.3 mm with a triple-line pattern was confirmed with TVUS, and luteal phase support was performed with vaginal micronized progesterone (Endometrin 100 mg, three times per day) and progesterone intramuscular 100 mg/48 h. A positive pregnancy test confirmed pregnancy, and the patient delivered a healthy baby girl at 40 weeks via cesarean section.

Case 3

The third case involved a 31-year-old woman (G4P1A3) with Arabian (Emirati) ethnicity who presented to our clinic with primary infertility of 3 years. Her AMH level was 7.1 ng/mL, and her BMI was 32.2 kg/m².

Her reproductive history included a spontaneous miscarriage at 6 weeks, an early miscarriage after IVF/ICSI cycle, and a late miscarriage after IVF/ICSI cycle at 18 weeks, with treatments performed at another clinic. Her husband’s sperm analysis showed normozoospermia. During the TVUS, diffuse adenomyosis in the anterior wall and fundus was seen, with asymmetrical thickening, hyperechoic islands, fan-shaped shadowing, and translesional vascularity, with a score of 8 [10] (detailed description in Tables 1 and 2 and Figs. 5 and 6).

Fig. 5.

Transvaginal ultrasound image of Case 3 showing diffuse adenomyosis in anterior wall and fundus (A) asymmetrical thickening (arrow; B), hyperechoic islands, fan-shaped shadowing, and translesional vascularity

Fig. 6.

Diagnostic hysteroscopy image of Case 3 after hormonal suppression (A, B)

She underwent ovarian stimulation with an antagonist protocol, yielding nine chromosomally normal embryos. An initial single day-5 blastocyst transfer in a downregulated HRT cycle was unsuccessful. A hormonal suppression with 3 months of GnRH-a (triptoreline acetate 3.75 mg/monthly) and letrozole 5 mg daily was performed, followed by a diagnostic hysteroscopy. Endometrial preparation with HRT 6 mg/day of estradiol was done for 12 days, achieving an endometrial thickness of 7.9 mm with a triple-line pattern. Single eFET was planned 120 h after starting luteal phase support with vaginal micronized progesterone (Endometrin 100 mg, three times per day) and supplemental intramuscular progesterone (100 mg every other day). A positive pregnancy test confirmed the success of the cycle, and the patient delivered a healthy baby boy at 36 weeks via cesarean section.

Discussion

This case series describes a customized protocol for adenomyotic uteri management involving GnRH agonists, aromatase inhibitors, and office hysteroscopy-based endometrial irrigation prior to initiating HRT for endometrial preparation. This protocol successfully prepared the endometrium for implantation, resulting in improved outcomes. Furthermore, intramuscular progesterone was added to standard vaginal micronized progesterone for intensive luteal phase support, addressing the inherent progesterone resistance frequently seen in adenomyosis. Ectopic endometrial tissue in adenomyosis is characterized by aromatase hyperactivity and impaired estrogen inactivation, resulting in elevated estradiol levels and increased pro-inflammatory cytokine activity [7, 8]. Moreover, adenomyosis demonstrates increased expression of estrogen receptors alongside downregulation of progesterone receptors, further contributing to progesterone resistance [9, 10].

All patients presented multiple hallmarks of adenomyosis. A notable finding in recent studies [8, 9] is the capability of adenomyotic tissue to produce estrogen autonomously. As observed in Cases 1 and 2, elevated basal estradiol levels after downregulation (Table 3) were not due to peripheral estrogen conversion, as the patients were not obese, underscoring the unique estrogenic activity of adenomyotic tissue. Hormonal suppression with standard treatments, such as GnRH-a, may not always adequately suppress estradiol levels. As reported by Cozzolino et al. [11], some patients maintained elevated estradiol concentrations even after multiple GnRH-a injections. However, combining GnRH-a and aromatase inhibitor letrozole demonstrated efficacy in further reducing serum estradiol. Standardized protocols for dose and duration are still lacking [12].

Table 3.

General characteristics of the patients and euploid frozen embryo transfer cycle outcomes

Category	Case 1	Case 2	Case 3
Age (years)	32	31	31
BMI (kg/m2)	25.33	23.3	32.2
AMH (ng/mL)	7.2	7.79	7.1
AFC (n)	24	22	20
Previous eFET cycle	No previous eFET	One natural cycle and one HRT	Decapeptyl 3.75 mg + HRT
Endometrial thickness before LPS	No previous eFET	8 mm triple line	7.7 mm triple Line
P4 day of eET with conventional LPS	No previous eFET	9.45 ng/mL	10.63 ng/mL
Suppression length: Decapeptyl 3.75 intramuscularly + letrozole 5 mg/day	2 months	2 months	3 months
E2 after hormonal suppression	31.71 pg/ml	17.12 pg/mL	5.79 pg/mL
Endometrial thickness before LPS	7.9 mm triple line	8 mm triple line	7.9 mm triple line
P4 day of eET with intensive LPS	9.79 ng/mL	20.23 ng/mL	7.41 ng/mL
Treatment outcome	Live birth	Live birth	Live birth

BMI, body mass index; E2, estradiol; P4, progesterone; eET, euploid embryo transfer; LPS, luteal phase support

One crucial variable to consider is monitoring estradiol levels closely and asking patients for symptoms of hot flashes. Basal levels of estradiol after GnRH-a suppression are frequently not reported in previous publications, yet they are essential to optimize treatment efficacy to ensure adequate hormonal suppression [11]. Regular transvaginal ultrasounds (TVUS) are also recommended to assess uterine size, wall thickness, and adenomyotic changes [12]. However, due to potential severe menopausal symptoms, counseling and support are critical for patient adherence, especially given limited data on the treatment’s impact during later pregnancy stages, as there are very limited alternatives for patients who cannot tolerate the regimen of hormone suppression.

Progesterone resistance, common in adenomyosis, has been linked to increased estrogen receptor expression, downregulating progesterone receptors’ expression through epigenetic silencing [13] [14]. Consequently, intensive luteal phase support and careful monitoring of progesterone levels before and after the embryo transfer are critical. Notably, all FETs presented here were performed with euploid blastocysts, eliminating aneuploidy as a variable, which is a clear strength for the case series herein. Transferring euploid embryos in such challenging cases is crucial to limit variables that could affect implantation and successful outcomes [12].

All patients underwent office diagnostic hysteroscopy to evaluate the cervical canal and uterine cavity prior to initiating endometrial preparation with HRT [15]. In addition to its diagnostic purpose, this procedure offers potential benefits, such as cavity irrigation, which may mechanically remove detrimental anti-adhesive glycoproteins from the endometrial surface. Furthermore, aseptic inflammation of the endometrium seems to trigger immune system modulation and alterations in gene expression, thereby enhancing endometrial receptivity [15].

Despite the promising results, some questions about this approach still need clarification, such as the optimal duration for combination treatment or the patient profiles that will benefit the most. Further research should be encouraged, including close monitoring of hormonal levels and ultrasound response (that is, shrinkage of the lesions) through the hormonal suppression treatment [3]. Additionally, including supportive strategies for managing progesterone resistance in adenomyosis seems mandatory, as the quality of evidence is still poor [16]. Complex cases, especially those involving infertility or recurrent pregnancy loss, require individualized management strategies.

Conclusions

Combining GnRH-a with letrozole offers a promising alternative for such patients. However, further research, including well-designed randomized controlled trials (RCTs), is crucial to validate and optimize these protocols, ensuring evidence-based improvements in treatment outcomes.

Abbreviations

HRT

Hormonal replacement therapy

eFET

Euploid frozen embryo transfer

COCs

Cumulus–oocyte complexes

BMI

Body mass index

Author contributions

MFM: data gathering and writing original draft and revising. LM: writing the manuscript and validation of data and revising. BL: supervisor; validation of data, and revising the final version of the manuscript. HF: conceptualization and revising of the final version. JE: investigation and data gathering.

Funding

Not applicable.

Data availability

The data underlying this article are available in the article and its supplementary material. Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Declarations

Ethics approval and consent to participate

Ethical approval was obtained (Research Ethics Committee—REFA126-2406-ABU-008-LMV). All participants signed informed consent forms to participate in the study and publication.

Consent for publication

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Competing interests

Not applicable.