Probably because there are small lesions unlike cysts that are raised. I know it's irritating but less frustrating when you don't expect them to show anything but a cyst. But even if it did show up there would be no way to know exactly what it was.

I was told that it's because it just looks like any other tissue....It's blood and cells....there's nothing unique about it to make it look any different than other tissue on the mri scan.

I was told that the diagnostic tests like MRI and u/s **might** pickup scar tissue, and if someone has lots of scar tissue or ovarian cysts it could suggest possible endomeriosis. But scar tissue doesn't always show up either so that's why they recommend the lap for the official diagnosis.

Before my endo diagnosis I had a CAT scan, an MRI, and several u/s. The CAT scan picked up both ovarian cysts (report said possible dermoid cysts, or cancer - endo was not mentioned at this point). The 1st u/s I had they said was an error because it showed an ovarian torsion and they said there was no way I could have a torsion because I was walking/driving/etc. So they did a 2nd u/s a couple of days later, and then I wasn't allowed to leave the office until my doctor came in and did a 3rd u/s to confirm the torsion.

So when I went into surgery, based on the imaging reports, I thought I was dealing with just the ovarian torsion and then like a dermoid cyst. I think of the 5 doctors I went to only one mentioned possible endometriosis, and she didn't explain what that was or why she considered it.

My current ob/gyn does periodic u/s at her office just to keep an eye on my cysts. Just to make sure they don't get too big, or that I don't get a torsion again. I used to get them every 3 months, but now I only get them every 6-8 months.