Complete pleural symphysis is predicted by a blunted costophrenic angle

Complete pleural symphysis from adhesions is a troublesome intraoperative finding. A blunted costophrenic angle without pleural effusion is an indicator of prior pleural disease; however, the diagnostic accuracy of blunted costophrenic angles for complete pleural symphysis is unclear. This study to determine whether complete pleural symphysis is predicted by the finding of a blunted costophrenic angle.

The operative records of patients who underwent thoracic cavity surgery were retrospectively reviewed. Cases with ipsilateral pleural effusion identified using preoperative computed tomography were excluded. A receiver-operating characteristic curve for complete pleural symphysis was generated to determine the optimal cut-off value of the costophrenic angle based on intraoperative findings for adhesions. The cases were then divided into blunted and sharp costophrenic angle groups, and the sensitivity, specificity, accuracy, positive likelihood ratio, and negative likelihood ratio for complete pleural symphysis were calculated for both groups.

In total, 1204 thoracic sides (709 right, 495 left) of 1186 cases were reviewed. According to the receiver-operating characteristic curve, the optimal cut-off value of the costophrenic angle was 51°. The rate of complete pleural symphysis was significantly higher in the blunted group than in the sharp group (p < 0.001). The sensitivity, specificity, accuracy, positive likelihood ratio, and negative likelihood ratio were 70.7, 96.1, 95.3%, 18.3, and 0.30, respectively.

Complete pleural symphysis was predicted by a blunted costophrenic angle with moderate sensitivity and high specificity, accuracy, and positive likelihood ratio. Evaluation of the costophrenic angle could, therefore, be an efficient, simple, and convenient screening tool.