Rosenstein's sign, also known as Sitkovskiy sign, is a sign of acute appendicitis.
[1] It is observed when tenderness in the right lower quadrant increases when the patient moves from the supine position to a recumbent posture on the left side.
[2] The sign is named after the almost forgotten Jewish German physician and director of The Jewish Hospital, Berlin, Paul Rosenstein (1875–1964).
Sitkovskiy's symptom[3] is the equivalent symptom.