Adenomyosis and Its Relationship with Endometriosis: A Unified Disease Spectrum and the Role of Advanced Ultrasound Imaging

Introduction: Adenomyosis and endometriosis are chronic, estrogen-dependent gynecologic disorders that frequently coexist and share overlapping clinical, histopathologic, and molecular features. Historically regarded as distinct entities, growing evidence now supports the concept that adenomyosis and endometriosis represent interconnected manifestations of a single disease spectrum of uterine and extrauterine endometrial dysfunction. Both conditions contribute substantially to chronic pelvic pain, abnormal uterine bleeding, infertility, and reduced quality of life, yet remain underdiagnosed due to delayed recognition and limitations of conventional diagnostic pathways.

Recent advances in imaging—particularly expert-level transvaginal ultrasound—have fundamentally altered the diagnostic approach to adenomyosis and clarified its close relationship with endometriosis.

Definition and Pathophysiology of Adenomyosis: Adenomyosis is defined by the presence of endometrial glands and stroma within the myometrium, accompanied by smooth muscle hyperplasia and fibrosis. Unlike endometriosis, which involves ectopic endometrial tissue outside the uterus, adenomyosis represents internal myometrial invasion of endometrial tissue.

The prevailing pathogenic mechanisms include:

1. Junctional zone disruption, allowing direct invagination of basal endometrium into the myometrium
   
   

2. Tissue injury and repair (TIAR) mechanisms, driven by uterine hyperperistalsis
   
   

3. Estrogen-driven inflammation, promoting myometrial hypertrophy and fibrosis
   
   

4. Neuroangiogenesis, contributing to pain generation
   
   

These processes result in a thickened, irregular junctional zone, altered uterine contractility, and progressive structural distortion of the uterus.

Adenomyosis as a Chronic and Progressive Disease: Adenomyosis is increasingly recognized as a chronic, progressive inflammatory condition, rather than a static uterine abnormality. Symptoms often begin in early reproductive life and worsen over time, particularly in the presence of coexisting endometriosis.

Clinical manifestations include:

-Dysmenorrhea (often severe and progressive)
-Heavy or prolonged menstrual bleeding
-Chronic pelvic pain
-Deep dyspareunia
-Infertility and recurrent implantation failure

Disease progression is associated with increasing myometrial fibrosis, impaired uterine peristalsis, and altered endometrial receptivity.

Relationship Between Adenomyosis and Endometriosis: Epidemiologic and Clinical Association: Adenomyosis and endometriosis coexist in a significant proportion of patients. Large imaging and surgical series report coexistence rates ranging from 30% to over 60%, particularly in women with deep infiltrating endometriosis. Patients with both conditions typically experience:

-Earlier symptom onset
-More severe pain
-Higher rates of infertility
-Reduced response to hormonal therapy
This frequent coexistence challenges the traditional separation of the two diseases.

Shared Pathophysiologic Mechanisms. Both adenomyosis and endometriosis share:

-Estrogen dependence
-Progesterone resistance
-Chronic inflammation
-Neuroangiogenesis
-Fibrotic remodeling
-Altered immune response

Importantly, the junctional zone appears to be a critical interface linking the two diseases. Junctional zone hyperplasia and dysfunction facilitate both inward invasion (adenomyosis) and outward dissemination (endometriosis). This has led to the concept of “endomyometrial dysfunction” as a common origin.

Clinical Implications of Coexisting Disease

Failure to recognize adenomyosis in patients with endometriosis has important consequences:

-Persistent pain after endometriosis surgery
-Incomplete symptom resolution
-Reduced fertility outcomes
-Inappropriate surgical planning
-Misinterpretation of treatment failure
Thus, comprehensive evaluation of both uterine and extrauterine disease is essential.

Role of Advanced Ultrasound in Diagnosis. Limitations of Traditional Diagnostic Approaches

Historically, adenomyosis was diagnosed only after hysterectomy, while MRI was considered the non-invasive reference standard. However, MRI availability, cost, and protocol variability limit its widespread use, particularly for early disease.

Routine pelvic ultrasound often fails to identify adenomyosis due to insufficient evaluation of the junctional zone and myometrial architecture.

Expert-Level Transvaginal Ultrasound. Modern expert-level transvaginal ultrasound has emerged as a highly accurate diagnostic modality for adenomyosis when standardized criteria are applied. Key sonographic features include:

-Junctional zone thickening or irregularity
-Asymmetric myometrial thickening
-Myometrial cysts
-Hyperechoic islands
-Fan-shaped acoustic shadowing
-Globular uterine enlargement
-Translesional vascularity on color Doppler

When performed by trained operators, ultrasound demonstrates diagnostic accuracy comparable to MRI, with the added advantage of real-time assessment and accessibility.

Integrated Ultrasound Mapping: Adenomyosis and Endometriosis Together. Advanced ultrasound mapping protocols allow simultaneous evaluation of:

-Adenomyosis (internal uterine disease)
-Endometriosis (external pelvic disease)

This integrated approach provides:

-A complete disease phenotype
-Improved symptom correlation
-More accurate surgical planning
-Better fertility counseling
-Improved selection of medical vs surgical treatment

Importantly, recognition of adenomyosis can explain persistent symptoms in patients previously treated for endometriosis alone.

Adenomyosis and endometriosis are closely related chronic inflammatory diseases that frequently coexist and should be evaluated as part of a unified diagnostic framework. Advances in expert-level transvaginal ultrasound now allow accurate, non-invasive identification of both conditions in a single examination, overcoming historical diagnostic limitations.

Recognition of their interrelationship is essential for effective symptom management, fertility optimization, and long-term disease control. As imaging standards evolve, integrated ultrasound mapping is increasingly positioned as a cornerstone in the comprehensive evaluation of women with chronic pelvic pain and abnormal uterine bleeding.