In certain embodiments, a sampling assembly is for use with a main analyzer. The main analyzer is configured to sense an analyte in a body fluid obtained from a patient through a first fluid passageway extending from the main analyzer. The sampling assembly includes an instrument portion separate from the main analyzer and including at least one sensor. The instrument portion is removably engaged with the first fluid passageway. The at least one sensor is in sensing engagement with the first fluid passageway such that the at least one sensor can sense a property of a fluid within the first fluid passageway.