Elliot K. Fishman M.D.
Johns Hopkins Hospital

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“Endometriosis is a common benign gynecologic disorder, defined by endometrial glands and stroma outside of the endometrial cavity. Endometriosis can be associated with infertility or pain symptoms, including cyclic pelvic pain, dysmenorrhea, dyspareunia, dysuria, and dyschezia. The correlation between lesions and pain symptoms or infertility in endometriosis is poorly understood. There is a wide spectrum of symptom severity, and the stage of endometriosis on laparoscopy correlates poorly with the extent and severity of pain. Some patients with minimal disease have debilitating pain, while other women with severe stage III–IV disease are asymptomatic.”
Invasive and non-invasive methods for the diagnosis of endometriosis
Albert L Hsu et al.
Clin Obstet Gynecol. 2010 Jun; 53(2): 413–419.

“Endometriosis is a common cause of pelvic pain and infertility, with as many as 30% of women with endometriosis demonstrating tubal involvement at laparoscopy. Ruptured deep pelvic endometriomas release blood products that cause adhesions and fibrosis, which may lead to findings that can mimic PID, such as the development of complex pelvic masses, nodularity of the uterosacral ligaments, and peritubal adhesions with tubal obstruction.”
Pelvic Inflammatory Disease: Multimodality Imaging Approach with Clinical-Pathologic Correlation 
Revzin MV et al.
RadioGraphics 2016; 36:1579–1596

“Imaging has limited utility in the diagnosis of endometriosis, as it lacks adequate resolution to identify adhesions or superficial peritoneal implants. Ultrasound is cheap and easy to perform, but user-dependent; MRI is more accurate but considerably more expensive. As CT of the pelvis does not visualize pelvic organs well, it is not useful in the diagnosis of endometriosis. An important role for the CT scan with contrast is to detect ureteral involvement and possible renal insufficiency.”
Invasive and non-invasive methods for the diagnosis of endometriosis
Albert L Hsu et al.
Clin Obstet Gynecol. 2010 Jun; 53(2): 413–419.

“Endometriomas contain a dense, brown, chocolate-like fluid and are pseudocysts formed by the invagination of endometriosis within the ovarian cortex. Adhesions are usually associated with endometriomas and attach them to nearby pelvic structures. Deep infiltrating endometriosis (DIE) is a nodular blend of fibromuscular tissue and adenomyosis. These lesions are primarily found in the uterosacral ligaments or cul de sac, but may also involve the rectovaginal septum. Patients with DIE may present with deep dyspareunia and various bowel symptoms from diarrhea to dyschezia during menses, depending on the location of the deep lesions.”
Invasive and non-invasive methods for the diagnosis of endometriosis
Albert L Hsu et al.
Clin Obstet Gynecol. 2010 Jun; 53(2): 413–419.

“At laparoscopy, endometriosis may be visualized as peritoneal implants, peritoneal windows, endometriomas, and deep infiltrating nodules of endometriosis which may each be associated with adhesions. The color, size, and morphology of endometriotic lesions are highly variable from person to person. Endometriotic implants in the pelvis occur more often on the left side, although the reason for this asymmetry is not known.”
Invasive and non-invasive methods for the diagnosis of endometriosis
Albert L Hsu et al.
Clin Obstet Gynecol. 2010 Jun; 53(2): 413–419.

“The CT appearance of endometriomas can be nonspecific, although the presence of multiple complex lesions, high-attenuation components within the mass, and hematosalpinx help to narrow the differential diagnosis. Solid invasive endometriosis, which is commonly found in the rectouterine pouch or posterior cul-de-sac, often extends to or invades the posterior myometrium and can mimic an adhesion from previous PID.”
Pelvic Inflammatory Disease: Multimodality Imaging Approach with Clinical-Pathologic Correlation 
Revzin MV et al.
RadioGraphics 2016; 36:1579–1596

”Endometriosis is a common chronic gynaecological disease affecting 10 to 15% of women of reproductive age. It is defined by the presence of functional ectopic endometrial tissue outside the uterus. Depending on the site of the endometrial implants, three main clinicopathological types of endometriosis can be distinguished, generally intricately linked: superficial peritoneal endometriosis, ovarian endometriosis (cystic lesions known as endometriomas) and deep pelvic endometriosis. Extrapelvic locations (abdominal, pleural) are rare.”
Imaging of intestinal involvement in endometriosis
Massein A et al.
Diagnostic and Interventional ImagingVolume 94, Issue 3, March 2013, Pages 281-291

“Deep gastrointestinal involvement in endometriosis is characterised by fibrous, retractile thickening of the intestinal wall. The most common location is the upper rectum, in contiguity with a lesion of the torus uterinus. As part of a preoperative assessment, it is essential to establish an accurate and exhaustive map of intestinal lesions so that the surgeon can plan hisactions. Transvaginalsonography and MRI correctly analyse pelvic and rectal involvement. Given the frequency of multiple intestinal sites, particularly sigmoid and associated ileo-caecal lesions, water enema CT should be performed.”
Imaging of intestinal involvement in endometriosis
Massein A et al.
Diagnostic and Interventional ImagingVolume 94, Issue 3, March 2013, Pages 281-291

”The literature regarding imaging features of AWE is scarce, with many authors concluding that the usefulness of imaging is limited to determining the location and extent of involvement of the lesion with respect to the surrounding tissue. Interestingly, the few studies that consider the sonographic features of abdominal wall endometriosis have described specific features, including solid lesions with ill-defined blurred outer borders and the presence of a hyperechoic ring. The latter correspond to adipose tissue that has become edematous and is filled with cells of inflammatory origin. Our findings are consistent with these results, as the “gorgon” sign may be a CT correlate to the hyperechoic rim seen on ultrasound.”
Abdominal wall endometriosis: differentiation from other masses using CT features 
Gail Yarmish et al.
Abdom Radiol (NY). 2017 May ; 42(5): 1517–1523

“Abdominal wall masses have a wide differential diagnosis, which includes endometriosis and other neoplastic and inflammatory etiologies. Abdominal wall endometriosis is commonly associated with scars related to Cesarean section, hysterectomy and other uterine surgery. However, in a substantial minority of cases, AWE does not arise in association with abdominal scarring or in the context of prior surgery. The condition may be detected incidentally on imaging or it may come to medical attention because of chronic abdominal or pelvic pain. As with the pelvic variety, malignant transformation is a rare but recognized complication. Although the diagnosis may at times be made based on clinical presentation, in many scenarios, clinical manifestations of AWE are nonspecific, and patients may complain only of vague abdominal pain, a tender mass, or they may be asymptomatic Moreover, symptoms may not occur until years after uterine surgery (reported cases range from 6 months to 20 years), and as such may not be recognized as being related to prior surgical treatment.”
Abdominal wall endometriosis: differentiation from other masses using CT features 
Gail Yarmish et al.
Abdom Radiol (NY). 2017 May ; 42(5): 1517–1523 

49 year old woman with severe abdominal pain
Past history of endometriosis and robotic hysterectomy with morcellation

Contrast enhanced axial (A) and coronal CT(B)shows an enhancing lobulated retroperitoneal mass (yellow arrow). The mass is displacing the 3d portion of the duodenum

T1 weighted MR (C) shows the retroperitoneal mass (blue arrow) is iso-intense to muscle with few scattered high signal intensity foci. MR post contrast (D) shows the mass (yellow arrow) abutting and encasing the aorta and compressing the IVC

Although percutaneous biopsy of the retroperitoneal mass yielded endometriosis, the radiological findings were deemed suspicious for a malignant tumor. The patient underwent extensive surgical resection and final pathology was polypoid endometriosis