Ultrasound-Guided Small-Caliber Catheter Drainage for Complex Septated Pleural Effusions: Discrimination of Septal Characteristics for Outcomes

Wenqiang Lin,1 Peifen Chen2 1Department of Ultrasound, The First Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong Province, People’s Republic of China; 2Department of Radiology, The First Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong Province, People’s Republic of ChinaCorrespondence: Peifen Chen, Department of Radiology, The First Affiliated Hospital of Shantou University Medical College, 57 Changping Road, Shantou, Guangdong Province, 515041, People’s Republic of China, Tel +8613822869774, Email 13822869774@163.comPurpose: The objective of this study was to identify the sonographic and clinical predictors of drainage procedure failure using small-caliber catheters under ultrasound guidance for complex septated pleural effusions.Materials and Methods: In this retrospective cohort study, we analyzed 145 consecutive patients who underwent ultrasound-guided small-caliber (6- or 8-Fr) catheter drainage for complex septated pleural effusion at a single tertiary center. Demographic, clinical, and pleural fluid data were collected. Sonographic images were reviewed to classify septation complexity (widespread vs few) and to quantitatively measure septal thickness. Multivariable logistic regression was used to identify independent predictors of drainage failure.Results: Unsuccessful drainage occurred in 79 patients (54.5%). Widespread septations (72.2% vs 36.4%, P< 0.001) and greater septal thickness (3.3 vs 2.1 mm, P< 0.001) were more common in the unsuccessful group. Multivariable analysis identified widespread septations (adjusted odds ratio [aOR]=2.94, P=0.033) and septal thickness (aOR=3.39 per mm, P< 0.001) as independent predictors of failure. The optimal cut-off for septal thickness was > 2.4 mm (sensitivity 82.3%, specificity 69.7%). An alternative cut-off of > 1.8 mm provided high sensitivity (93.7%) and a negative likelihood ratio (LR−) of 0.1 for ruling out failure.Conclusion: Quantitative sonographic assessment of septation complexity and thickness independently predicts small-caliber catheter drainage failure in complex septated pleural effusions. Incorporating these parameters into pre-procedural evaluation can aid in risk stratification and guide individualized management, potentially facilitating timely escalation to advanced therapies when indicated.Keywords: pleural effusion, septation, ultrasonography, drainage, catheterization