The optimal diagnostic algorithm for diagnosing CAPA is currently unknown, and this question is actively being investigated in an ongoing multinational explorative trial in conjunction with the European Confederation of Medical Mycology (ECMM). The most common methods to date include attempting to recover Aspergillus spp. on culture media of bronchoalveolar fluid (BALF) and tracheal aspirate, as well as utilizing serologic biomarker testing such as the conventional Galactomannan (GM) from BALF, tracheal aspirate, and serum specimens. Other diagnostic tests that may prove useful also include Aspergillus PCR, serum (1→3)-β-d-glucan (BDG), the Aspergillus galactomannan lateral flow assay (LFA) (IMMY, Norman, Oklahoma, USA), and the Aspergillus-specific lateral-flow device (LFD) test (OLM Diagnostics, Newcastle Upon Tyne, UK).