Bronchopleural fistula is an anomalous connection between the bronchial and pleural cavity. It is unusual and occurs often secondary to resection of the lung for malignancies, although there are several other known etiologies for this condition. It is difficult to diagnose and is associated with a high incidence of mortality.
Bronchopleural fistula (BPF) is a rare condition which presents a diagnostic and therapeutic challenge to physicians and is often fatal . It is defined as an atypical communication between the bronchial and pleural cavities.
BPF can be classified on the basis of the duration of symptoms as acute, subacute or chronic and on the basis of etiology as accidental (penetrating chest wall wounds)  or iatrogenic (lung resection), secondary to malignancies, and infections . Approximately 25% of BPF occur after lung resection surgery, especially for malignant pulmonary tumors . In these patients, BPF typically presents post chemotherapy or in advanced stages, the fistula develops from the operated lobectomy stump. Other causes of BPF include parenchymal pleural fibroelastosis , tuberculosis , chemotherapy and radiation .
Pre-operative risk factors for the development of BPF are steroid administration, H.influenzae infection, fever, anemia, leukocytosis, tracheostomy and bronchial lavage for clearance of mucus plugs . BPF following lung resection typically occurs within two weeks of the surgery. If it presents early (in acute cases) i.e. in the first few postoperative days, then it could be due to inadequate closure or breakdown of the anastomoses. These patients present with a cough with purulent expectoration, emphysema in the subcutaneous tissues, hypotension, and dyspnea. On examination, a mediastinal shift is noted.
Subacute and chronic BPF occur in immunocompromised or debilitated patients who present with long-standing productive cough, debility, malaise, wasting and fever. Chronic infection can lead to fibrosis within the pleural cavity.
BPF diagnosis can present a dilemma as it is often difficult to localize the fistula and its origin. The workup may necessitate repeated bronchoscopic as well as imaging procedures for detection of the condition . Flexible bronchoscopy is useful for diagnosis as well as therapy  as it enables visualization of the fistula, obtain samples for microbiological evaluation, detect infectious etiologies and perform therapeutic procedures .
Plain X-ray chest is one of the first radiological tests to be performed and is likely to show a hydropneumothorax.
Other imaging procedures like methylene blue bronchography and computed tomography (CT) are performed as part of the workup with CT scan being considered the gold standard test for diagnosis of BPF and its etiology . Findings on CT include an air-fluid level, hydropneumothorax or pneumothorax or a pneumomediastinum with mediastinal shift, a fistulous tract along with the underlying pulmonary pathology or tumor.
Xenon ventilation scintigraphy can also help to detect a BPF   .