To diagnose plague, the patient's presence in a plague-affected area should first be investigated. Then, characteristic clinical findings in the patient, along with blood tests, confirm the diagnosis of plague. Furthermore, to determine if the patient has bubonic plague, a sample of fluid is taken from swollen lymph nodes and sent to a laboratory for examination. To check for pneumonic plague, a bronchoscopy may be necessary, involving drawing fluid from the respiratory tract via a tube inserted through the nose, mouth, or throat. A doctor suspecting plague will begin antibiotic treatment immediately, before test results confirm the diagnosis, because plague is a rapidly progressing epidemic disease requiring early treatment.