Abstract Rationale Within transudative pleural effusions, hepatohydrothorax (HHT) may differ in composition from cardiac or renal transudates. Because CT attenuation in Hounsfield units (HU) reflects fluid density, we investigated whether pleural fluid attenuation distinguishes HHT from other transudates. Methods We conducted a single-center retrospective study at Wyckoff Heights Medical Center (Brooklyn, NY) includings as adults undergoing thoracentesis from January 2022-December 2024. Inclusion required complete serum and pleural chemistries to apply Light’s criteria and a pre-procedure chest CT. Analyses were restricted to transudative effusions. HHT was proxied using a structured “Liver Failure” field (YES/NO), acknowledging potential misclassification. On axial CT, four circular regions of interest were placed within the largest dependent pleural pocket; their mean defined the HU average. Data were non-normally distributed (Shapiro-Wilk test); group comparisons were performed using the Mann-Whitney U test. Results Of 45 transudates, 7 (15.6%) were labeled HHT and 38 (84.4%) other transudates. Age and sex distributions were similar between groups. Pleural fluid attenuation was lower in HHT than other transudates (mean ± SD: 6.41 ± 4.20 vs 10.40 ± 4.58 HU; median IQR: 5.06 4.06-6.54 vs 10.47 6.93-12.57; p = 0.021), with a mean difference of − 3.99 HU. Precision was limited by the small HHT sample. Conclusions Among transudative effusions, HHT exhibits lower CT attenuation, averaging ∼4 HU less than other transudates. While HU alone is not diagnostic, very low attenuation in a transudate may raise suspicion for HHT, prompting earlier evaluation for portal-hypertensive physiology and potential diuretic or procedural interventions. Conversely, higher HU values may suggest alternative etiologies. These findings complement, but do not replace, pleural fluid analysis and clinical assessment. Key limitations include the retrospective design, small sample size, and single-center setting. Multicenter studies are warranted to validate these observations. This abstract is funded by: None
Chepkunov et al. (Fri,) studied this question.