03/29/2026
This reel shows a negative triangle sign.
In patients with suspected endometriosis, ultrasound is not just about detecting disease. It is about mapping disease extent well enough to guide surgical planning.
The sliding sign is an essential part of assessing the cul-de-sac, but in patients with a retroverted uterus, it may not tell the full story. The triangle sign is a helpful supplemental maneuver.
If pressure is released with the vaginal probe and a small triangle of peritoneal fluid appears between the posterior uterus and the posterior vaginal fornix, that is a positive triangle sign and suggests the cul-de-sac is not obliterated.
If that triangle does not appear, the sign is negative, suggesting obliteration of that space.
A negative triangle sign can therefore be an important clue to posterior compartment disease and surgical complexity.
Dynamic ultrasound matters. Anatomy matters. And subtle signs like this can change how we understand the case before anyone ever enters an operating room.
Have you seen this sign before?