Why is adenomyosis frequently undiagnosed?

Why Adenomyosis Is Frequently Undiagnosed

Adenomyosis remains frequently undiagnosed because it lacks pathognomonic symptoms, has no universally agreed-upon diagnostic criteria, often coexists with other gynecological conditions that mask its presence, and until recently required hysterectomy for definitive diagnosis—leading to systematic underrecognition in younger women who have not undergone surgery. 1, 2, 3

Nonspecific and Variable Clinical Presentation

• The clinical symptoms of adenomyosis—heavy menstrual bleeding, dysmenorrhea, dyspareunia, and pelvic pain—overlap extensively with endometriosis, fibroids, and other gynecological conditions, making clinical diagnosis unreliable. 1, 3
• A substantial proportion of women with adenomyosis are completely asymptomatic, meaning the condition goes undetected unless imaging is performed for other reasons. 1, 2, 3
• Physical examination findings are nonspecific and do not allow definitive diagnosis, requiring imaging or histopathology for confirmation. 4

Imaging Limitations and Technical Challenges

• Transvaginal ultrasound using MUSA criteria demonstrates only 82.5% sensitivity and 84.6% specificity, meaning approximately 17-18% of cases are missed even with standardized protocols. 5, 6
• In symptomatic patients, approximately 16% may not demonstrate any direct ultrasound signs despite having clinical adenomyosis, creating false negatives when diagnostic criteria are strictly applied. 5
• Standard pelvic ultrasound protocols do not routinely include the detailed assessment needed to identify adenomyosis features, unlike the expanded protocols developed for endometriosis mapping. 7
• MRI has better sensitivity (78-88%) and specificity (67-93%) but is not routinely performed for pelvic symptoms due to cost and availability constraints. 5, 6

Lack of Standardized Diagnostic Criteria

• There are currently no universally agreed-upon diagnostic criteria for adenomyosis among pathologists, radiologists, or clinicians. 2, 3
• The histopathological diagnosis itself has poor inter-observer reproducibility, particularly for limited disease, leading to extreme variations in reported prevalence. 1
• Different imaging modalities use different diagnostic thresholds (junctional zone thickening measurements, myometrial features), creating inconsistency in diagnosis across institutions. 1, 4

Coexistence with Other Gynecological Conditions

• Adenomyosis frequently coexists with endometriosis and uterine fibroids, making it difficult to attribute symptoms to adenomyosis specifically or to recognize it as a separate entity. 1, 2, 3
• When multiple conditions are present, clinicians may focus on the more obvious pathology (such as large fibroids) and overlook adenomyosis. 3
• On ultrasound, adenomyosis can obscure endometrial visualization, potentially leading to missed endometrial pathology and vice versa. 5, 6

Historical Diagnostic Paradigm

• For decades, adenomyosis was considered exclusively a histopathological diagnosis made after hysterectomy, typically in perimenopausal women. 1, 3
• This historical approach meant younger women of reproductive age were systematically underdiagnosed, as they would not undergo hysterectomy. 1
• Only with recent imaging advancements has non-invasive diagnosis become possible, but clinical awareness and adoption lag behind the technology. 1, 2

Diagnostic Pitfalls and Mimics

• MRI findings of adenomyosis can mimic uterine leiomyomas, myometrial contractions, adenomatoid tumors, and even malignancies such as endometrial stromal sarcoma. 4
• Adenomyosis varies widely in histopathologic features (sparse glands), growth patterns (polypoid adenomyoma, adenomyotic cysts), and hormonal responses, creating diverse imaging appearances. 4
• Focal adenomyosis is particularly challenging to distinguish from fibroids on routine imaging. 8, 4

Clinical Integration Failures

• Clinical context must be integrated with imaging findings to avoid underdiagnosis, especially in symptomatic populations where other causes have been excluded and adenomyosis remains highly probable even without direct imaging signs. 5
• Many clinicians are not trained to recognize subtle imaging features or to correlate imaging findings with the clinical presentation systematically. 1, 8
• The absence of a validated clinical scoring system (analogous to the Endometriosis Fertility Index) means there is no standardized approach to combine symptoms, examination, and imaging findings. 7