Bibasilar

Bibasilar is a medical adjective describing involvement or location at the bases of a paired organ, most often the lungs. The term combines bi- meaning two with basilar, referring to the base or lower part. In radiology and clinical reporting, bibasilar indicates abnormalities located at both lower lung zones on imaging studies such as chest radiographs or CT scans. It is used to specify that findings affect the bases bilaterally rather than being restricted to one side.

Common uses in chest imaging include bibasilar atelectasis, bibasilar edema, bibasilar pneumonia or consolidation, and bibasilar pleural effusions. Bibasilar atelectasis describes linear or subsegmental collapse at the bases, often seen with shallow breathing, postoperative conditions, or sedation. Bibasilar edema typically shows basilar-predominant interstitial markings or airspace opacity, sometimes with Kerley B lines. Bibasilar pneumonia refers to infection with predominant involvement of both bases, presenting as basilar consolidation. Bibasilar effusions indicate fluid collection that settles at the bases of the lungs.

Clinical significance lies in localization: identifying bibasilar findings helps direct diagnostic thinking and further testing, but the description is not diagnostic on its own and must be interpreted in the clinical context and with other imaging features.

See also: chest radiography, pulmonary bases, atelectasis, interstitial edema, consolidation.