A specimen collection receptacle formed by a channel disposed within the wall of a toilet bowl. The receptacle is located above the weir water line. The receptacle comprises a channel open to the interior of the bowl having opposed non-parallel side walls. The side walls may be joined opposite the opening. The side walls may be joined by a bottom wall. The bottom wall may be arcuate. The side walls may be non-planar. The walls may exhibit a roughened surface. The receptacle may comprise an optical window. The receptacle may comprise a cuvette. The receptacle may be in communication with one or more light emitting probes. The receptacle may be self-cleaning. The receptacle may comprise a replaceable module disposed in the wall of the toilet bowl. The receptacle may be located at the front of the toilet bowl. The receptacle may be disposed in a toilet bowl liner or insert.