Pleural Effusion Phenotype and Ultrasound Guidance Approach Associated with Unplanned Pigtail Pleural Catheter Removal in an Adult Intensive Care Unit: A Single-Center Retrospective Cohort Study

Background: Pleural pigtail catheters are widely used in intensive care units (ICUs), but factors associated with unplanned removal remain incompletely characterized. Methods: We conducted a single-center retrospective cohort study of adult ICU catheter-placement episodes from December 2020 to March 2025. Effusions were grouped as complex (exudative, empyema, malignant, or malignancy-related) or simple (transudative or hemothorax). The primary outcome was unplanned removal for a catheter-related complication or escalation to surgery. Associations were evaluated using Firth penalized logistic regression. Results: Among 175 screened episodes, 140 were analyzed; unplanned removal occurred in 12 (8.6%). Complex effusions (adjusted odds ratio [aOR] 6.50, 95% confidence interval [CI] 1.59–26.55) and ultrasound-assisted insertion (aOR 10.72, 95% CI 1.92–59.94) were associated with higher odds of unplanned removal. Reclassifying hemothorax as complex attenuated but did not reverse the phenotype association (aOR 4.84, 95% CI 1.17–19.93). The ultrasound association may reflect case selection, operator workflow, or procedural complexity rather than causality. Because 33 death-related episodes were excluded, the 8.6% rate applies to episodes with classifiable non-death endpoints, not all screened episodes. Conclusions: These findings are hypothesis-generating and insufficient to change clinical practice without prospective multicenter validation.