Most definitive diagnosis of sinusitis is:
There are many possible methods to make diagnosis of rhinosinusitis but there is much debate related to best method. It has become increasingly clear that the diagnosis of ARBS is best made on clinical grounds and criteria. Ref Scott Brown 7/e,Vol 2,p 1142.
X ray PNS
Proof puncture
Sinoscopy
Transillumination test
Nose and paranasal sinuses