Endometriosis is a chronic disorder predominantly affecting women of childbearing age.
It is defined as presence of ectopic endometrial glands and stroma outside the uterus.
This condition manifests in as many as 10% of premenopausal woman and is an important cause of chronic pelvic pain and infertility.
Several hypotheses have been proposed to explain the pathogenesis of endometriosis,
but the most widely accepted theory is metastatic implantation of endometrial tissue from retrograde menstruation.
Endometriosis can involve almost any body part with a notary exception,
the spleen.
However,
endometriosis most commonly involves the ovaries and pelvic peritoneum followed by GI system and urinary system in order of frequency.
Distribution and types of endometriosis:
Common lesions
Ovaries:
-Endometrial cyst (endometrioma).
Pelvic peritoneum:
Peritoneal implants are subdivided into superficial and deep.
Superficial implants are the implants in the covering of the uterus,
tubes,
uterine ligament,
anterior and posterior cul-de-sacs,
rectosegmoid,
and bladder.
Deep infiltration is defined as the presence of endometrial tissue at least 5 mm beneath the peritoneal surface lead to invasion of the sub-peritoneal space.
Sub peritoneal Space:
-Anterior with involvement of the bladder.
-Posterior with involvement of the torus,
utero-sacral ligaments,
posterior vaginal fornix,
rectovaginal septum,
and anterior wall of rectosegmoid junction. -Lateral involvement of the ureters (Extrinsic).
Peritoneal cavity:
-Adhesions.
Other GI tract locations:
-Lower rectum and sigmoid.
Less common lesions
Intratubal implants
Peritoneal endometriotic psudocyst
Other GI tract locations: appendix,
caecum,
small bowl,
and transverse colon.
Cutaneous: scars,
umbilicus,
and inguinal region.
Rare lesions
Diaphragm
Thoracic cavity: Pleura and lung.
Other urinary tract locations: Kidneys and ureters.
Other GI tract locations:Gall bladder,
liver,
and pancreas.
Nervous system: CNS and peripheral nerves.
Lymphatic system: Pelvic lymph nodes.
The gold standard for diagnosis of endometriosis is by laparoscopy and histopathology.
However,
imaging plays an important role in preoperative disease depiction and mapping.
Transvaginal US should be carried out as first line imaging when investigating cases of infertility and pelvic pain and for evaluation of the ovaries.
MRI is excellent for determining extent of deep pelvic involvement and depiction of extensive pelvic adhesions and ureteral involvement.
Rectal endoscopic sonography with high-frequency probes (7.5 - 12 MHz) has been recommended for the detection of rectal,
rectovaginal,
uterosacral or recto sigmoid endometriosis,
but it has poor penetration.
Computed tomography (CT) usually is not very helpful in the diagnosis of endometriosis.
This poster reviews the different sites of involvement in endometriosis and discusses radiological appearances with emphasis on MRI.