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).
Normal sliding motion of the uterus is regarded as a “positive” sliding sign.
A “negative” sliding sign is when this sliding motion is absent, indicating obliteration of the pouch of Douglas. Studies have shown that in women with suspected endometriosis undergoing laparoscopy, this sign has greater than 90% accuracy in predicting the likelihood of POD obliteration, with a sensitivity ranging from 72-83% and specificity of 97-100% 1.
Given the complexity of the surgery and prolonged operating times associated with POD obliteration due to peritoneal endometriosis, it is useful for the laparoscopic surgeon to know the status of the POD preoperatively.