Unknown Pleural Effusion

Today at Parkland Morning Report we talked about what to do when a patient presents with a persistent unilateral pleural exudative effusion and the initial tests are unremarkable. This is a follow up to an earlier post regarding pleural effusions. Below are some key points:

  • Up to 25% of pleural effusions will remain undiagnosed after the 1st diagnostic thoracentesis. (1)
  • Malignant pleural effusions are diagnosed only 60-65% of the time on cytology alone. Repeat thoracentesis and cytology may increase the yield. (2)
  • Sensitivity of pleural fluid cytology in malignant pleural effusions range from 40 to 87%. (3)
  • CT chest with pleural fluid enhancement is recommended in all patients with undiagnosed pleural effusion. Can identify optimal sites for CT guided needle biopsy and invasion from underlying structures that would suggest malignancy.
  • Pleural biopsy follows CT scan if pleural effusion remains undiagnosed. Pleural biopsy can be achieved by the following techniques:
    • Percutaneous – Ultrasound or CT guided needle biopsy
    • Thorascopic – Useful when percutaneous is negative, no visible mass on CT, or patchy disease is suspected
    • Open biopsy has fallen out of favor since the growing use of thorascopic

Check out the references below to learn more:

1. Venekamp, et al. Respirology. 2005

2. Garcia LW, et al. Modern Pathology. 1994

3. BTS guidelines for the investigation of a unilateral pleural effusion in adults. 2003