Background
Endometriosis is a common inflammatory gynecologic disorder characterized by functional endometrial glands and stroma outside of the uterus. The disorder affects approximately 2–8% of the general population and up to 50% of women with infertility. Clinical findings of endometriosis include pelvic pain, abdominal pain, dysmenorrhea, dyspareunia, and infertility. Endometriosis can have gastrointestinal involvement presenting with small bowel obstruction, rectal bleeding, constipation, bladder involvement presenting with urinary urgency, frequency, hematuria, and thoracic involvement presenting with pleural effusions, pleuritic chest pain, and hemoptysis. Endometriosis is categorized into endometriomas, superficial peritoneal endometriosis, and deep infiltrating endometriosis. The most common location for deposits is the ovaries and pelvic peritoneum. There is often a 4–8-year delay in diagnosis, owing to low sensitivity and specificity of clinical examinations and variety in symptomatology.
Educational Goals / Teaching Points
The objective of this educational exhibit is to discuss the epidemiology and clinical features of endometriosis and review the imaging findings of different types and locations of endometriosis in a case-based presentation.
Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The most commonly used imaging modalities for endometriosis are transvaginal and transrectal ultrasound and MRI. Laparoscopy with biopsy-proven ectopic endometrial tissue remains a diagnostic tool for patients with negative imaging. Endometriomas are characterized as thick-walled ovarian pseudocysts containing proteinaceous and hemorrhagic products. On transvaginal ultrasound, endometriomas can range from a hemorrhagic ovarian cyst appearance early on in their formation to the classic homogeneous ground glass echogenicity with chronic bleeding. Other notable features include a fluid-fluid level, avascular internal nodule, or papillary projections. Approximately 50% of endometriomas are bilateral. Superficial peritoneal endometriosis is characterized as superficial peritoneal implants with less than 5 mm of peritoneal invasion. Deep infiltrating endometriosis is characterized as implants greater than 5 mm of peritoneal invasion with fibromuscular hyperplasia and surrounding endometrial-like glands. On ultrasound, deposits appear avascular and hypoechoic with irregular solid masses. Detection with transvaginal ultrasound is dependent on the location; rectosigmoid deep infiltrating endometriosis and endometriomas have the highest sensitivity and specificity rates.
Conclusion
Endometriosis is a complex disorder that is challenging to diagnose. Imaging plays an important role in the diagnosis; ultrasound is the first-line imaging modality, and MRI is the second-line imaging modality. Radiologists should be familiar with the different imaging findings and locations of endometriosis.
