Hemothorax: What It Is, Why It Happens, and How It's Treated
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer
Hemothorax is a condition in which blood collects in the pleural space and can press on the lung so it cannot fully inflate. A major injury, chest trauma and surgery are the most common causes. Trouble breathing or intense chest pain means you should get to an emergency room. Treatment removes the blood with a needle or chest tube. [1]
What the research says
Guidelines favor pigtail catheters in stable patients and early surgery for retained blood. An Eastern Association for the Surgery of Trauma guideline screened 6,391 articles and used 14 to build its recommendations, most of them retrospective with very low-quality evidence. For traumatic hemothorax it conditionally recommends pigtail catheters in hemodynamically stable patients. For retained hemothorax it conditionally recommends video-assisted thoracoscopic surgery (VATS) rather than clot-dissolving therapy, performed early (within 4 days). (Patel et al., Am J Surg, 2021)
Small and large chest tubes performed similarly. A meta-analysis of 9 studies and 1,847 trauma patients with blood in the chest (714 small-bore, 1,233 large-bore) found failure rates of 17.8% vs 21.5% (no significant difference), with similar complication rates (12.3% vs 12.5%). The small-bore tubes stayed in for fewer days (4.3 vs 6.2). (Lyons et al., J Trauma Acute Care Surg, 2024)
Flushing the chest at tube placement lowered the need for a second procedure. A meta-analysis of 6 observational studies and 1,319 patients found that retained hemothorax needing a second intervention was less common with thoracic irrigation (10.7% vs 18.2%), with shorter tube time and hospital stay. The authors say randomized studies are needed before guidelines are written. (Lyons et al., J Trauma Acute Care Surg, 2025)
What Is Hemothorax?
Hemothorax is a serious condition in which blood collects in your pleural space. Your pleural space, also called the pleural cavity, is a hollow area between your lungs and your rib cage. Without treatment, this collection of blood can keep growing and put so much pressure on the outside of your lung that it cannot fully inflate. [1]
The pleural space helps control the pressure inside and around your lungs as you breathe. It holds a thin layer of pleural fluid, which helps the tissue that covers your lungs and lines your chest wall move as you breathe. A chest injury such as blunt trauma, surgery or another condition can cause blood to enter the pleural cavity and mix with that fluid. [1]
How Common Is It?
This condition is common. Experts estimate there are almost 300,000 cases each year in the U.S. [1]
What Causes Hemothorax?
A major injury, chest trauma and surgery are the most common causes. Other causes may include: [1]
A blood clotting disorder
Lung cancer
Pleural mesothelioma
Lung tissue death (pulmonary infarction)
Thoracic (chest) surgery, including heart surgery
Blood vessel damage during central venous catheter placement
Ehlers-Danlos syndrome
Tuberculosis
Who Is at Risk?
Anyone can develop this condition, especially after blunt trauma or another chest injury. Other risk factors include: [1]
Chest surgery: Surgeries on or near your lungs, such as open heart surgery or a lung transplant.
Repetitive chest injuries: Sports or activities with chest injury risks, such as football, hockey, weightlifting, boxing, martial arts and wrestling.
Symptoms and Complications
Common symptoms may include: [1]
Shortness of breath (dyspnea)
Rapid breathing (hyperventilation)
Rapid heart rate
Chest pain
Low blood pressure (hypotension)
Restlessness
Anxiety
Fever
In some severe cases, the condition may cause death. [1]
Possible Complications
Respiratory failure, when you have difficulty breathing or cannot breathe on your own
Hypovolemic (hemorrhagic) shock
Empyema, an infection in the pleural space
Scarring in the pleural tissue or lung tissue
When to Go to the ER
Get to an emergency room as soon as possible if you have trouble breathing or intense pain in your chest. [1] If you can, call your local emergency number instead of driving yourself.
How Is Hemothorax Diagnosed?
A healthcare provider will do a physical exam and listen to your lungs with a stethoscope, checking for abnormal sounds from the affected lung. They will also order tests to confirm the diagnosis. [1] Imaging tests may include: [1]
Chest X-ray
Computed tomography (CT) scan
Thoracentesis, in which a thin needle is used to remove fluid from the pleural space
How Is Hemothorax Treated?
Healthcare providers treat the condition by removing the collection of blood from your pleural cavity. [1]
Breathing Support First
Providers first support your breathing with oxygen therapy or, in severe cases, mechanical ventilation. [1]
Draining the Blood
Depending on how severe the bleeding is, providers will insert either a thin needle (thoracentesis) or a chest tube (thoracostomy) between your ribs to remove blood from the pleural space. Not every case needs a chest tube, and a minor one may only need a thin needle. [1]
If blood keeps filling the pleural cavity even with drainage, a surgeon makes an incision in your chest to reach the affected lung and treat the cause. This procedure is called a thoracotomy. You may also need a blood transfusion if you lose a lot of blood. [1]
Risks of Treatment
All treatments carry risks. These may include: [1]
Anesthesia problems
Pain
Bleeding
Infection, including pneumonia
Fluid buildup in the lungs (pulmonary edema)
Recovery and Outlook
Your recovery depends on what caused the bleeding and the type of treatment. You may need to stay in the hospital for several days if you need a chest tube or surgery. [1] With proper diagnosis and prompt treatment, most people fully recover without any long-term issues. [1]
Protect Your Lungs While Healing
As you recover, avoid activities that can damage or put pressure on your lungs, including: [1]
Smoking
Intense workouts, including heavy lifting or bending
Contact sports
Scuba diving or deep-sea diving
Traveling in airplanes
See your healthcare provider for any follow-up appointments. They may order imaging tests to make sure you are healing as expected. [1]
Can It Be Prevented?
You cannot prevent every cause. But you can lower your risk of chest injuries that could lead to bleeding around the lung by: [1]
Wearing protective padding for activities and sports that raise your risk of chest injury.
Always wearing a seatbelt in a car.
Using the proper tools or asking for help when reaching for items above your head, and never standing on stools, chairs or tables.
Using a cane, walker or crutches if you have difficulty walking or are at greater risk of falling.
Conclusion
Hemothorax is a serious condition that needs prompt medical attention. Whether it follows an accident, surgery or another illness, a collection of blood around the lung can quickly become dangerous. Drainage and treatment of the cause are effective, and most people recover fully. If you have trouble breathing or intense chest pain, especially after a chest injury, get emergency care right away.
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Frequently Asked Questions
Is hemothorax the same as a collapsed lung?
No. A collapsed lung is another name for pneumothorax, which is a different condition from blood in the pleural space. [1]
What is the difference between hemothorax and pneumothorax?
Hemothorax is when blood pools in your pleural space. Pneumothorax is when air enters your pleural space and presses against your lung, which makes it partially or fully collapse. [1]
Is hemothorax life-threatening?
The risk depends on how severe the bleeding is and how long it takes to stop. A minor case can heal without risks or complications, but a severe one can be fatal without prompt treatment. [1]
What is the difference between hemothorax and pleural effusion?
A pleural effusion is excess pleural fluid in the pleural space. A hemothorax is blood in the pleural space. [1]
Do all cases of hemothorax need a chest tube?
No. A minor case may only need a thin needle to drain blood from the pleural space. [1]
Will I need a blood transfusion?
You may need one if you lose a lot of blood. Your healthcare provider will decide based on your situation. [1]
How long is the hospital stay?
You may need to stay in the hospital for several days if you need a chest tube or surgery. Recovery depends on the cause and the type of treatment. [1]
Can sports cause hemothorax?
Repetitive chest injuries from certain sports can raise the risk. Cleveland Clinic lists football, hockey, weightlifting, boxing, martial arts and wrestling. [1]
Can I prevent hemothorax?
Not every cause can be prevented, but you can lower your risk of chest injury by wearing protective padding in risky sports, always wearing a seatbelt and preventing falls. [1]
Can I travel by plane after treatment?
Cleveland Clinic lists traveling in airplanes among the activities to avoid while you recover. Ask your provider when it is safe for you. [1]
What is pulmonary infarction?
Pulmonary infarction is death of lung tissue. It is listed as one possible cause of blood collecting in the pleural space. [1]
What is empyema?
Empyema is an infection in the pleural space and is listed as a possible complication of blood in the pleural space. [1]
Related Reading
Learn more in our guide to Decortication: Freeing a Trapped Lung, Open vs. VATS Surgery, Risks and Recovery.
References
Cleveland Clinic. Hemothorax. Cleveland Clinic. Last updated August 13, 2023. https://my.clevelandclinic.org/health/diseases/25239-hemothorax
Patel NJ, et al. Management of simple and retained hemothorax: A practice management guideline from the Eastern Association for the Surgery of Trauma. Am J Surg. 2021;221(5):873-884. PMID 33487403. https://doi.org/10.1016/j.amjsurg.2020.11.032
Lyons NB, et al. Small versus large-bore thoracostomy for traumatic hemothorax: A systematic review and meta-analysis. J Trauma Acute Care Surg. 2024;97(4):631-638. PMID 39213292. https://doi.org/10.1097/TA.0000000000004412
Lyons NB, et al. Thoracic irrigation for traumatic hemothorax: A systematic review and meta-analysis. J Trauma Acute Care Surg. 2025;98(2):337-343. PMID 39509686. https://doi.org/10.1097/TA.0000000000004479
Medical disclaimer
This article is for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have about a medical condition. Never disregard professional medical advice or delay seeking care because of something you have read here. If you think you may have a medical emergency, call your doctor or emergency services immediately.
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