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).

TheThis technique involves using gentle probe pressure to assess the sliding sign is performed as follows;

• In an anteverted uterus;
  • gentle pressure is placed against the cervix using the transducer, to establish whether the anterior rectum and sigmoid colon glides freely across the posterior aspect of the upper uterus, cervix and vaginal wall.
  • with their free hand on the lower abdomen, the sonographer in ballots the uterus between the palpating hand and the transducer, to assess whether the anterior bowel glides freely over the posterior uterine fundus
• In a retroverted uterus;
  • gentle pressure is placed against the posterior uterine fundus with the transducer to establish whether the anterior rectum glides freely across the posterior uterine fundus
  • with their free hand on the lower abdomen, the sonographer in ballots the uterus between the palpating hand and the transducer, to assess whether the anterior sigmoid glides freely over the anterior lower uterine segment. 

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.