A haemothorax is a collection of blood in the pleural space. It can be caused by penetrating or blunt thoracic trauma.



Clinical signs


Patients with a massive haemothorax are generally unstable – this should be detected clinically (as part of the primary survey)


Smaller haemothoraces may have subtle clinical findings

  • Decreased air entry
  • Dull percussion note





CXR: A small haemothorax might not be evident on CXR (especially if supine) – look for subtle increase opacification over the affected hemi-thorax.

Around 350-400ml of blood needs to be present before blunting of the costophrenic angle becomes evident on an erect CXR.


USS has a higher sensitivity than CXR for detecting smaller haemothoraces (92% sensitivity in one study).1


CT is the definitive imaging study for detecting a haemothorax





As there is a risk that an undrained haemothorax can lead to retained clot and then empyema, haemothoraces that are estimate to be 300-500ml or greater should be considered for drainage.


Controversy exists over the best size drain to insert – moderate sized drains (28-32F) have been shown to be as effective as large drains (36-40F) in managing traumatic haemothorax.3 Some studies have even shown that smaller (14F) pigtail drains might be as efficacious as larger drains4 however more research is needed.5


At present, it is still recommended that a larger bore drain (ie: 28-32 F) be inserted for patient with traumatic haemothoraces. See tube thoracostomy insertion.





Disposition – interhospital transfer guidelines





  1. Brooks A, Davies B, Smethhurst M, Connolly J. Emergency ultrasound in the acute assessment of haemothorax. Emergency Medicine Journal : EMJ. 2004;21(1):44-46. doi:10.1136/emj.2003.005438.
  2. Bilello JF, Davis JW, Lemaster DM. Occult traumatic hemothorax: when can sleeping dogs lie?. The American journal of surgery. 2005 Dec 31;190(6):844-8.
  3. Inaba K, Lustenberger T, Recinos G, Georgiou C, Velmahos GC, Brown C, Salim A, Demetriades D, Rhee P. Does size matter? A prospective analysis of 28–32 versus 36–40 French chest tube size in trauma. Journal of Trauma and Acute Care Surgery. 2012 Feb 1;72(2):422-7.
  4. Kulvatunyou N, Joseph B, Friese RS, Green D, Gries L, O’Keeffe T, Tang AL, Wynne JL, Rhee P. 14 French pigtail catheters placed by surgeons to drain blood on trauma patients: Is 14-Fr too small?. Journal of Trauma and Acute Care Surgery. 2012 Dec 1;73(6):1423-7.
  5. BET 4: Does size matter? Chest drains in haemothorax following trauma. Emerg Med J 2013;30:965-967.

About this guideline

First published: February 2018 (Author: Emma Batistich)
Updated April 2021, May 2024 (Savitha Bhagvan)
Approved by: Northern Region Trauma Network, Health New Zealand | Te Whatu Ora – Northern Region, NRHL, St John
Review due: 2 years