Provided herein is technology relating to methods for assaying a cell-containing body sample and particularly, but not exclusively, to treating a sample under conditions to cause cell lysis, preferably by means of a detergent; and subjecting the lysed sample to conditions causing the cleavage of nucleic acid molecules. The technology additionally relates to using nucleic acid cleavage conditions to enhance a membrane assay, a device for carrying out such an assay, and a kit for use in the assay.