bill of health n.
A certificate stating whether there is infectious disease aboard a ship or in a port of departure, given to the ship's master to present at the next port of arrival.
An attestation as to condition, especially a favorable one.
To “get a clean bill of health” is to be told by some authoritative source, generally a doctor, that one is perfectly healthy. The phrase is sometimes used figuratively to indicate that a person or organization has been found free of any sort of irregularity: “After looking into her financial background, the Senate gave the nominee a clean bill of health.”