From: Rabbi Moshe Sofer
To: Rabbi Aharon
The Chasam Sofer rules that soaking a dried esophagus in cold water before inspection is permissible, because the Ran's principle that cold water seals perforations is irrelevant here — the inspection aims to detect absorbed redness indicating disease penetration, not holes, and such markers cannot be washed away. He partially accepts his student's suggestion that the Ran's principle resolves Tosfos's question on Chullin 11b, but notes the resolution fails if the drowning occurred in warm water.
Source: Shu"t Chasam Sofer YD §26