Peritoneal windows are areas where the thin membrane lining the abdomen, called the peritoneum, has become damaged or eroded—often due to endometriosis. These ‘windows’ can look like translucent or open defects, sometimes exposing underlying tissue. They’re thought to form from chronic inflammation as endometriosis lesions infiltrate and break down the peritoneum. Peritoneal windows may indicate active or aggressive disease, contributing to pain and adhesions. They’re usually identified during l