This test is highly specific for large effusions but may miss smaller amounts of fluid, which are better detected using the Bulge Sign . 2. Obstetric Ballottement
The patient lies flat (supine) with the leg fully extended and relaxed. ballottement
The clinician inserts two fingers into the vagina and gives a sharp upward tap against the lower segment of the uterus. If the fetus is present and not yet engaged in the pelvis, it will float upward and then fall back, tapping against the clinician’s fingers. This test is highly specific for large effusions