Clinical laboratories use two commonly used fluorescence in situ hybridization (FISH) methodologies. The first will be referred to as the historical standard FISH method, derived from cytogenetics laboratories that first performed FISH. The second method will be called the new histologic-based FISH method because it was derived from methods typically used in IHC laboratories.
Both methods should record the fixation time and time to fixation.
The procedure must be reproducible to be used efficiently in the clinical laboratory.