It is still unclear what, if any, causal relationship exists between toxic materials or autoimmune disease and endometriosis. There are immune system changes in people with endometriosis, such as an increase of macrophage-derived secretion products, but it is unknown if these are contributing to the disorder or are reactions from it.Endometriotic lesions differ in their biochemistry, hormonal response, immunology, inflammatory response when compared to endometrium. This is likely because the cells that give rise to endometriosis are a side population of cells. Similarly, there are changes in, for example, the mesothelium of the peritoneum in people with endometriosis, such as loss of tight junctions, but it is unknown if these are causes or effects of the disorder.In rare cases where imperforate hymen does not resolve itself prior to the first menstrual cycle and goes undetected, blood and endometrium are trapped within the uterus until such time as the problem is resolved by surgical incision. Many health care practitioners never encounter this defect, and due to the flu-like symptoms it is often misdiagnosed or overlooked until multiple menstrual cycles have passed. By the time a correct diagnosis has been made, endometrium and other fluids have filled the uterus and Fallopian tubes with results similar to retrograde menstruation resulting in endometriosis. The initial stage of endometriosis may vary based on the time elapsed between onset and surgical procedure.The theory of retrograde menstruation as a cause of endometriosis was first proposed by John A. Sampson.
Ultrasound
Vaginal ultrasound has a clinical value in the diagnosis of endometrioma and before operating for deep endometriosis. This applies to the identification of the spread of disease in individuals with well-established clinical suspicion of endometriosis. Vaginal ultrasound is inexpensive, easily accessible, has no contraindications and requires no preparation. Healthcare professionals conducting ultrasound examinations need to be experienced. By extending the ultrasound assessment into the posterior and anterior pelvic compartments the sonographer is able to evaluate structural mobility and look for deep infiltrating endometriotic nodules noting the size, location and distance from the anus if applicable. An improvement in sonographic detection of deep infiltrating endometriosis will not only reduce the number of diagnostic laparoscopies, it will guide management and enhance quality of life. Magnetic resonance imaging
Use of MRI is another method to detect lesions in a non-invasive manner. MRI is not widely used due to its cost and limited availability, however, it has the ability to detect the most common form of endometriosis (endometrioma) with a sufficient accuracy. It is recommended for the patient to receive an anti-spasmodic agent (hyoscine butylbromide for example), a big glass of water (if bladder is empty), to undergo MRI scanning in supine position and applying abdominal strap for having a better image quality from the MRI.Phased coil arrays are also recommended. Sequences
T1W with and without suppression of fat is recommended for endometriomas; meanwhile, sagittal, axial and oblique 2D T2W are recommended for deep infiltrating endometriosis.