From: Rabbi Moshe Sofer
To: Rabbi Wolf
The Chasam Sofer evaluates the Shach's ruling permitting a dissolved hemses (omasum) when no blood drop is present, against the Tevuos Shor's challenge that food could wash away the blood. He validates a proposed sfek sfeka argument for those who accept chezkas eino zavuach, but himself questions that concept, and rejects a chazakah d'hashta argument on grounds of a countervailing rov and constant movement of stomach contents.
Source: Shu"t Chasam Sofer YD §48