S'rose - I have an endometioma on my left ovary. They are sometimes called a chocolate cyst (try googling chocolate cyst you will find a lot more information). Endometrioma is basically endomoetrios of the ovaries which forms as a cyst on the outer surface. When they rupture they ooze a dark chocolate substance which spills into the adominal cavity can cause a lot of pelvic pain.

I recently had a lap and they knocked the top of mine but it has returned immediately. I am currently undergoing my first round of IVF and if it is unsucessful I may look at having another lap to remove the endometrioma completley, but this is more invasive. I watched a clip on YouTube of this being done. Was a little gross but gave a good view of what it looks like.