Endometriosis is a common plight in the infertility community. I’d love to dive deeper with you in regards to what endometriosis is and how it connects to other reproductive disorders, including infertility. Let's talk all about endometriosis. Endometriosis is inflammation of the peritoneum. Let’s break this down: Inflammation: when your tissues get hot, red, angry, and swollen. Think of a sprained ankle that swells and gets hot and discolored. You could also picture a rash on your skin, or any drug commercial on TV that shows a glowing ball of red pain.  Peritoneum means the tissue in between your organs.