The Peritoneal Factor Peritoneal factor infertility refers to abnormalities involving the peritoneum (lining of the surfaces of your internal organs) such as scar tissue (adhesions) or endometriosis (Figure 4). Endometriosis is a condition where tissue that normally lines the uterus begins to grow outside the uterus. This tissue may grow on any structure within the pelvis including the ovaries and is found in about 35% of infertile women who have no other diagnosable infertility problem.