Sliding sign The loss of the normal sliding sign is a dynamic sonographic sign performed during transvaginal ultrasound (TVS) of women with suspected pelvic peritoneal endometriosis. It indicates pouch of Douglas (POD) involvement and obliteration and is suggestive of deep infiltrating endometriosis (DIE). This technique involves using gentle probe pressure to assess whether the anterior rectum and sigmoid colon glides freely across the posterior aspect of the upper uterus, cervix and vaginal wa