Depth of pleural effusion in thoracentesis: Comparison of lateral, posterolateral and posterior approaches in the supine position

Jeong Min Ko, Jisoon Kim, Soo An Park, Kwang Nam Jin, Myeong Im Ahn, Seok Chan Kim, Dae Hee Han

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2 Scopus citations


Background: In patients who have difficulty sitting, thoracentesis is attempted in a supine position via lateral approach. Recently, a new table has been designed for supine thoracentesis. This table has gaps that allow access to the posterolateral and posterior hemithorax. Objectives: To compare important safety-related parameters between lateral, posterolateral, and posterior approaches in supine thoracentesis. Materials and Methods: First, two cadavers were placed supine on a table featuring gaps allowing access to the posterolateral and posterior hemithorax. Water was administered with sonographic measurement of the depth of pleural effusion (DPE) at the mid-axillary and posterior axillary line. Second, CT images were analyzed in 25 consecutive patients (32 free-shifting, moderate-tolarge effusions; mean, 668 (146 - 2020 mL). DPE, craniocaudal distance that effusion can be visualized (CCD), and presence of passive atelectasis at each of the lateral, posterolateral, and posterior routes was assessed. Results: In each cadaver, DPE in the posterolateral route was greater than that in the lateral route (P = 0.002, P < 0.001). The amount of pleural fluid enough to spread DPE to higher than 1 cm at the posterior axillary line was less than half the amount at the midaxillary line (500 mL vs. 1,100 mL; 800 mL vs. 1700 mL). CT showed that the DPEs and CCDs of posterolateral and posterior routes were greater than those of the lateral route (P< 0.001). In thirteen effusions (40.6%), DPE was greater than 1cmin both posterolateral and posterior routes but less than 1 cm in the lateral route. Frequencies of passive atelectasis in posterolateral and posterior routes (81.3% and 90.6%) were higher (P < 0.001) than that in the lateral route (28.1%). Conclusion: Safety-related parameters of posterolateral and posterior approaches in supine thoracentesis are far better than that of the conventional lateral approach.

Original languageEnglish (US)
Article numbere20919
JournalIranian Journal of Radiology
Issue number2
Publication statusPublished - Apr 1 2016
Externally publishedYes



  • Posterior approach
  • Posterolateral approach
  • Supine thoracentesis

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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