Rhinosinusitis can be divided among four subtypes: acute, recurrent acute, subacute and chronic, based on patient history and a limited physical examination. In most instances, therapy is initiated based on this classification. Antibiotic therapy, supplemented by hydration and decongestants, is indicated for seven to 14 days in patients with acute, recurrent acute or subacute bacterial rhinosinusitis. For patients with chronic disease, the same treatment regimen is indicated for an additional four weeks or more, and a nasal steroid may also be prescribed if inhalant allergies are known or suspected. Nasal endoscopy and computed tomography of the sinuses are reserved for circumstances that include a failure to respond to therapy as expected, spread of infection outside the sinuses, a question of diagnosis and when surgery is being considered. Laboratory tests are infrequently necessary and are reserved for patients with suspected allergies, cystic fibrosis, immune deficiencies, mucociliary disorders and similar disease states. Findings on endoscopically guided microswab culture obtained from the middle meatus correlate 80 to 85 percent of the time with results from the more painful antral puncture technique and is performed in patients who fail to respond to the initial antibiotic selection. Surgery is indicated for extranasal spread of infection, evidence of mucocele or pyocele, fungal sinusitis or obstructive nasal polyposis, and is often performed in patients with recurrent or persistent infection not resolved by drug therapy.